Laboratory and Test Terminology: Complete Guide to Diagnostic Testing

Laboratory and diagnostic testing forms the backbone of modern medical practice, enabling healthcare professionals throughout Dubai’s world-class medical facilities to detect diseases, monitor treatments, assess organ function, and guide clinical decision-making with precision and accuracy. From routine blood tests to advanced genetic sequencing, from basic X-rays to sophisticated MRI and PET scanning, the terminology of diagnostic medicine provides the vocabulary that connects patients, physicians, and laboratories in the pursuit of accurate diagnosis and optimal treatment outcomes. Understanding this terminology empowers patients to interpret their test results, engage meaningfully in discussions with their healthcare providers, and appreciate the sophisticated science underlying modern diagnostic medicine. Whether you are a healthcare professional seeking to refine your understanding, a patient preparing for diagnostic testing, or a student entering the medical field, this comprehensive glossary provides the foundation for understanding the language of diagnostic medicine used throughout Dubai’s healthcare system.

The landscape of diagnostic testing has transformed dramatically in recent decades, with technological advances enabling detection of diseases at earlier stages, personalized treatment approaches based on genetic profiles, and minimally invasive procedures that provide maximum information with minimal risk. Dubai’s healthcare infrastructure reflects these advances, with state-of-the-art laboratory facilities, advanced imaging centers, and specialized diagnostic services that rival the best medical centers worldwide. Understanding diagnostic terminology helps patients navigate this sophisticated landscape, ask informed questions about their testing options, and interpret the results that shape their healthcare decisions. The terms presented in this glossary represent the most commonly encountered vocabulary in diagnostic medicine, from basic laboratory panels to advanced molecular testing and imaging modalities.

Complete Blood Count (CBC) and Hematology Testing

The Complete Blood Count, universally known as the CBC, represents the most frequently performed laboratory test in medicine, providing essential information about the three main types of blood cells: red blood cells, white blood cells, and platelets. This fundamental test serves as a window into overall health, revealing conditions ranging from anemia and infection to leukemia and bleeding disorders. Understanding CBC terminology helps patients interpret this common test and appreciate the wealth of information it provides about their blood-forming organs and overall health status.

Red Blood Cell (RBC) Count measures the number of red blood cells per microliter of blood, with normal values differing between males and females. RBC count helps diagnose and monitor anemia (low RBC) and polycythemia (high RBC), with abnormalities prompting further investigation into causes such as nutritional deficiencies, chronic disease, blood loss, bone marrow disorders, or inappropriate red blood cell production.

Hemoglobin (Hb or Hgb) measures the concentration of the oxygen-carrying protein in red blood cells, expressed in grams per deciliter (g/dL). This is often considered the most clinically meaningful component of the CBC because it directly indicates the blood’s oxygen-carrying capacity. Understanding hemoglobin values helps patients recognize when they are anemic (low hemoglobin) or polycythemic (high hemoglobin) and appreciate how these conditions affect their energy levels, exercise tolerance, and overall health.

Hematocrit (Hct) represents the percentage of blood volume occupied by red blood cells, calculated from the RBC count and mean corpuscular volume. While less precise than hemoglobin measurement, hematocrit provides useful information about blood viscosity and the proportion of red blood cells in the bloodstream. Changes in hematocrit parallel changes in hemoglobin and are used to assess hydration status, anemia, and polycythemia.

Mean Corpuscular Volume (MCV) calculates the average volume of individual red blood cells, helping classify anemia based on cell size. Low MCV (microcytic anemia) suggests iron deficiency or thalassemia, normal MCV (normocytic anemia) suggests chronic disease or blood loss, and high MCV (macrocytic anemia) suggests vitamin B12 or folate deficiency, liver disease, or myelodysplastic syndromes.

Mean Corpuscular Hemoglobin (MCH) and Mean Corpuscular Hemoglobin Concentration (MCHC) provide additional information about the hemoglobin content and concentration within red blood cells. These values help characterize anemia types and may provide clues to underlying causes, particularly in distinguishing iron deficiency from other causes of microcytic anemia.

Red Cell Distribution Width (RDW) measures the variation in red blood cell size, with increased RDW indicating greater variation (anisocytosis). This value helps distinguish between different causes of anemia—for example, iron deficiency typically causes increased RDW, while thalassemia often presents with normal RDW despite microcytosis.

White Blood Cell (WBC) Count measures the number of white blood cells per microliter of blood, with the total count and differential (percentage of different types) providing crucial information about immune status and infection. Leukocytosis (high WBC) suggests infection, inflammation, stress, or leukemia, while leukopenia (low WBC) may indicate viral infections, bone marrow disorders, autoimmune diseases, or medication effects.

White Blood Cell Differential breaks down the total WBC count into its component types: neutrophils, lymphocytes, monocytes, eosinophils, and basophils. Each cell type serves different immune functions, and patterns of elevation or reduction help diagnose specific conditions. Neutrophilia suggests bacterial infection or inflammation, lymphocytosis suggests viral infections or lymphoproliferative disorders, eosinophilia suggests allergic conditions or parasitic infections, and monocytosis suggests chronic inflammation or certain infections.

Platelet Count measures the number of platelets per microliter of blood, essential for normal blood clotting. Thrombocytopenia (low platelets) causes bleeding tendency, while thrombocytosis (high platelets) may indicate reactive conditions (inflammation, iron deficiency) or myeloproliferative neoplasms.

Mean Platelet Volume (MPV) measures the average size of platelets, with larger platelets typically being younger and more active. Changes in MPV provide information about platelet production and destruction rates, helpful in evaluating thrombocytopenia.

Comprehensive Metabolic Panel (CMP) and Basic Metabolic Panel (BMP)

The Comprehensive Metabolic Panel (CMP) and its abbreviated version, the Basic Metabolic Panel (BMP), provide essential information about electrolyte balance, kidney function, liver function, and glucose metabolism. These panels represent workhorses of clinical chemistry, ordered routinely for screening, diagnosis, and monitoring of a wide range of conditions. Understanding CMP terminology helps patients interpret these common tests and appreciate how they reflect organ function and metabolic status.

Glucose measures blood sugar levels, typically after an 8-hour fast. Elevated fasting glucose suggests diabetes mellitus or prediabetes, while low glucose (hypoglycemia) may indicate medication effects, insulinoma, or other metabolic conditions. Understanding glucose values and their interpretation is essential for the large population of Dubai residents with diabetes or at risk for diabetes.

Blood Urea Nitrogen (BUN) measures the blood concentration of urea nitrogen, a waste product of protein metabolism that is normally excreted by the kidneys. Elevated BUN suggests decreased kidney function, dehydration, or high protein intake, while low BUN may indicate liver disease or overhydration.

Creatinine measures the blood concentration of creatinine, a waste product of muscle metabolism that is excreted by the kidneys. Creatinine is more specific than BUN for kidney function because it is less affected by diet and hydration status. Estimating kidney function using creatinine, age, sex, and race (eGFR calculation) provides the most clinically useful assessment of renal function.

Estimated Glomerular Filtration Rate (eGFR) calculates kidney function based on creatinine, age, sex, and race, expressed as milliliters per minute per 1.73 square meters. This value categorizes kidney function from normal (eGFR >90) through various stages of chronic kidney disease to kidney failure (eGFR <15). Understanding eGFR helps patients with kidney disease appreciate their functional status and the implications for treatment and prognosis.

BUN/Creatinine Ratio compares BUN to creatinine levels, providing information about the cause of acute kidney injury. Elevated ratio suggests prerenal azotemia (decreased blood flow to kidneys), while normal or low ratio suggests intrinsic kidney damage.

Sodium measures blood sodium concentration, essential for fluid balance and nerve/muscle function. Hyponatremia (low sodium) causes symptoms ranging from nausea and headache to seizures and coma, and has many causes including heart failure, liver disease, kidney disease, SIADH, and overhydration. Hypernatremia (high sodium) typically results from dehydration or excessive sodium intake.

Potassium measures blood potassium concentration, critical for cardiac and muscle function. Both hypokalemia and hyperkalemia can cause life-threatening cardiac arrhythmias. Understanding potassium levels helps patients with kidney disease, heart failure, or those taking medications that affect potassium appreciate the importance of this value.

Chloride measures blood chloride concentration, which parallels sodium levels and helps assess acid-base status. Chloride abnormalities typically reflect changes in sodium or acid-base balance rather than primary chloride disorders.

Carbon Dioxide (CO2 or TCO2) measures the total carbon dioxide content, primarily reflecting bicarbonate levels and helping assess acid-base status. Changes in CO2 help diagnose and classify acidosis and alkalosis, respiratory and metabolic disorders.

Calcium measures blood calcium concentration, regulated by parathyroid hormone, vitamin D, and kidney function. Hypocalcemia causes neuromuscular irritability and tetany, while hypercalcemia causes fatigue, weakness, kidney stones, and cardiac arrhythmias. Understanding calcium helps patients with parathyroid disease, vitamin D deficiency, or kidney disease appreciate their metabolic status.

Phosphorus measures blood phosphate concentration, important for bone metabolism and energy production. Abnormalities occur with kidney disease, parathyroid disorders, malnutrition, and refeeding syndrome.

Magnesium measures blood magnesium concentration, essential for nerve and muscle function. Hypomagnesemia may cause arrhythmias, muscle weakness, and seizures, and often accompanies hypokalemia and hypocalcemia.

Total Protein measures all proteins in the blood, primarily albumin and globulins. Low total protein suggests malnutrition, liver disease, kidney disease (protein loss), or protein-losing enteropathy.

Albumin measures the most abundant blood protein, produced by the liver, which maintains oncotic pressure and carries various substances. Low albumin causes edema and suggests liver disease, malnutrition, kidney disease (protein loss), or chronic inflammation.

Alkaline Phosphatase (ALP) enzyme found in liver, bone, and other tissues. Elevated ALP suggests liver disease (cholestasis) or bone disease (Paget’s disease, osteomalacia, bone tumors, healing fractures). Isoenzyme testing can distinguish hepatic from skeletal sources.

Aspartate Aminotransferase (AST) enzyme found in liver, heart, muscle, and other tissues. Elevated AST suggests liver injury, heart damage, muscle injury, or hemolysis. Pattern with ALT helps differentiate causes of liver enzyme elevation.

Alanine Aminotransferase (ALT) enzyme found primarily in liver, more specific for hepatocellular injury than AST. Elevated ALT suggests liver injury from hepatitis, drugs, toxins, or other causes. The AST/ALT ratio (De Ritis ratio) provides information about cause and severity of liver disease.

Bilirubin measures the breakdown product of heme from worn-out red blood cells, processed by the liver. Elevated bilirubin causes jaundice and may result from increased production, decreased liver uptake, impaired conjugation, or impaired excretion (obstruction). Direct (conjugated) and indirect (unconjugated) fractions help localize the site of dysfunction.

Gamma-Glutamyl Transferase (GGT) enzyme found primarily in liver and bile ducts. Elevated GGT suggests liver disease, particularly cholestasis or alcohol use. GGT is often elevated with ALP when the source is hepatic but not when the source is bone.

Lipid Panel and Cardiovascular Risk Testing

The lipid panel provides essential information about cardiovascular risk by measuring blood levels of cholesterol and triglycerides, the fats that contribute to atherosclerosis when present in excessive amounts. Understanding lipid terminology helps patients appreciate their cardiovascular risk and the rationale for lipid-lowering therapy, which has become one of the most important interventions for preventing heart attacks and strokes in Dubai’s population.

Total Cholesterol measures all cholesterol in the blood, including HDL, LDL, and VLDL. While historically used for risk assessment, total cholesterol is now understood to be less useful than individual lipoprotein fractions because it does not distinguish between protective (HDL) and harmful (LDL) cholesterol.

Low-Density Lipoprotein (LDL) Cholesterol is often called “bad cholesterol” because it deposits cholesterol in arterial walls, contributing to atherosclerosis. LDL cholesterol is calculated (total cholesterol minus HDL cholesterol minus triglycerides/5) or directly measured. Understanding LDL goals helps patients appreciate why statin therapy is prescribed and what levels are targeted.

High-Density Lipoprotein (HDL) Cholesterol is often called “good cholesterol” because it removes cholesterol from arterial walls and transports it back to the liver for excretion. Higher HDL levels are associated with lower cardiovascular risk, and low HDL (<40 mg/dL in men, <50 mg/dL in women) is a cardiovascular risk factor.

Very Low-Density Lipoprotein (VLDL) carries triglycerides from the liver to peripheral tissues and contributes to atherosclerosis. VLDL is calculated from triglycerides and is typically elevated in metabolic syndrome and diabetes.

Triglycerides are fats stored in adipose tissue and carried in blood lipoproteins. Elevated triglycerides (>150 mg/dL) are associated with cardiovascular risk and pancreatitis. Very high triglycerides (>500 mg/dL) require treatment to prevent pancreatitis.

Non-HDL Cholesterol represents total cholesterol minus HDL, including LDL, VLDL, and lipoprotein(a). This value captures all atherogenic lipoproteins and is increasingly recommended as a secondary treatment target, especially in patients with high triglycerides.

Lipoprotein(a) [Lp(a)] is a genetic variant of LDL that is an independent risk factor for cardiovascular disease. Elevated Lp(a) (>50 mg/dL or >125 nmol/L) increases cardiovascular risk and may influence treatment decisions, particularly in patients with premature cardiovascular disease or family history.

Apolipoprotein B (ApoB) is the main protein component of atherogenic lipoproteins (LDL, VLDL, Lp(a)). Each atherogenic particle contains one ApoB molecule, making ApoB a measure of the number of atherogenic particles. ApoB may be a better cardiovascular risk marker than LDL cholesterol in some patients.

Apolipoprotein A1 (ApoA1) is the main protein component of HDL. Low ApoA1 levels are associated with increased cardiovascular risk, complementing HDL cholesterol measurement.

Glycemic Testing and Diabetes Monitoring

Testing for diabetes and glycemic control provides essential information about glucose metabolism, enabling diagnosis, classification, and monitoring of diabetes mellitus and related conditions. Understanding glycemic terminology helps the large population of Dubai residents with diabetes and prediabetes interpret their test results and appreciate the importance of glycemic control in preventing complications.

Fasting Plasma Glucose (FPG) measures blood glucose after an 8-hour fast, used for diabetes screening and diagnosis. Fasting glucose 100-125 mg/dL indicates prediabetes (impaired fasting glucose), while fasting glucose >=126 mg/dL suggests diabetes (requiring confirmation).

Hemoglobin A1c (HbA1c) measures the percentage of hemoglobin that is glycated (attached to glucose), reflecting average blood glucose over the past 2-3 months. HbA1c <5.7% is normal, 5.7-6.4% indicates prediabetes, and >=6.5% indicates diabetes. Understanding HbA1c helps patients appreciate the importance of long-term glycemic control.

Oral Glucose Tolerance Test (OGTT) measures blood glucose before and after drinking a standardized glucose solution, assessing how well the body handles glucose load. This test is used for diagnosing gestational diabetes and sometimes for diagnosing type 2 diabetes or prediabetes when other tests are equivocal.

Random Plasma Glucose measures blood glucose at any time, without fasting. Random glucose >=200 mg/dL with symptoms of diabetes suggests diabetic hyperglycemia.

C-Peptide measures C-peptide levels, a byproduct of insulin production that reflects endogenous insulin secretion. This test helps distinguish type 1 diabetes (low/no C-peptide) from type 2 diabetes (normal or elevated C-peptide) and assesses beta cell function.

Insulin measures circulating insulin levels, useful for assessing insulin resistance (high insulin with normal glucose) or insulin deficiency (low insulin with high glucose).

Urine Glucose historically used for diabetes screening but now rarely used because blood glucose testing is more accurate. Urine glucose appears only when blood glucose exceeds the renal threshold (~180 mg/dL).

Inflammatory and Autoimmune Markers

Inflammatory and autoimmune markers help diagnose and monitor conditions characterized by inflammation or abnormal immune activity. Understanding these tests helps patients with inflammatory and autoimmune conditions appreciate the status of their disease and the rationale for treatment.

C-Reactive Protein (CRP) is an acute-phase reactant produced by the liver in response to inflammation. Elevated CRP indicates active inflammation from infection, autoimmune disease, tissue injury, or malignancy. High-sensitivity CRP (hs-CRP) is used for cardiovascular risk assessment, with elevated levels suggesting increased risk.

Erythrocyte Sedimentation Rate (ESR) measures how quickly red blood cells settle in a tube over one hour, indirectly reflecting inflammation. Elevated ESR occurs with infection, autoimmune disease, malignancy, anemia, and pregnancy. ESR is a less specific but useful marker for inflammatory conditions.

Antinuclear Antibody (ANA) is an autoantibody directed against nuclear antigens, used to screen for autoimmune diseases. Positive ANA occurs in systemic lupus erythematosus, Sjogren’s syndrome, scleroderma, and other autoimmune conditions. Titer and pattern provide additional information.

Rheumatoid Factor (RF) is an autoantibody associated with rheumatoid arthritis and other autoimmune conditions. Positive RF occurs in 70-80% of rheumatoid arthritis patients and may also be positive in other autoimmune diseases, infections, and elderly individuals.

Anti-Cyclic Citrullinated Peptide (Anti-CCP) is an autoantibody highly specific for rheumatoid arthritis. Positive anti-CCP strongly suggests rheumatoid arthritis, particularly in patients with negative RF.

Anti-Double Stranded DNA (Anti-dsDNA) is an autoantibody highly specific for systemic lupus erythematosus (SLE). Anti-dsDNA levels correlate with disease activity in lupus nephritis.

Anti-Smith (Anti-Sm) is an autoantibody specific for SLE, though less sensitive than anti-dsDNA. Positive anti-Sm is diagnostic of SLE.

Antineutrophil Cytoplasmic Antibodies (ANCA) include antibodies against proteinase 3 (PR3) and myeloperoxidase (MPO), associated with vasculitides including granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA).

Complement C3 and C4 measure levels of complement proteins, which are consumed during active immune complex diseases. Low complement levels occur in active SLE and other autoimmune conditions.

Human Leukocyte Antigen (HLA) Typing identifies HLA antigens on cell surfaces, used for transplant matching and diagnosis of conditions associated with specific HLA types (HLA-B27 with ankylosing spondylitis, HLA-DQ2/DQ8 with celiac disease).

Thyroid Function Testing

Thyroid function tests assess the functional status of the thyroid gland, which regulates metabolism through thyroid hormone production. Understanding thyroid terminology helps patients with thyroid disorders interpret their test results and appreciate the importance of proper thyroid hormone levels for overall health.

Thyroid-Stimulating Hormone (TSH) is produced by the pituitary gland and stimulates the thyroid to produce thyroid hormone. TSH is the most sensitive test for thyroid dysfunction—high TSH suggests hypothyroidism (underactive thyroid), while low TSH suggests hyperthyroidism (overactive thyroid).

Free Thyroxine (Free T4) measures unbound, biologically active thyroid hormone. Low free T4 with high TSH confirms primary hypothyroidism. High free T4 with low TSH confirms primary hyperthyroidism.

Free Triiodothyronine (Free T3) measures unbound, biologically active T3 (the more active thyroid hormone). Free T3 helps assess hyperthyroidism severity and monitor treatment, particularly in T3 toxicosis.

Total T4 and Total T3 measure bound plus unbound thyroid hormone. These tests are less useful than free hormone measurements because binding proteins affect levels.

Thyroid Antibodies include anti-thyroid peroxidase (anti-TPO), anti-thyroglobulin, and thyroid-stimulating immunoglobulin, which help diagnose autoimmune thyroid disease (Hashimoto’s thyroiditis, Graves’ disease).

Infectious Disease Testing

Infectious disease testing identifies pathogens and the immune response to infection, enabling appropriate treatment and monitoring. Understanding infectious disease terminology helps patients appreciate how infections are diagnosed and monitored.

Culture involves growing microorganisms from clinical specimens (blood, urine, sputum, wound, cerebrospinal fluid) to identify the causative organism and determine antibiotic susceptibility. Blood cultures detect bacteremia, urine cultures detect urinary tract pathogens, and sputum cultures identify respiratory pathogens.

Polymerase Chain Reaction (PCR) amplifies DNA or RNA from pathogens, enabling rapid detection of organisms that are difficult to culture. PCR is used for detecting viral infections (COVID-19, HIV, hepatitis), bacterial infections, and genetic testing.

Rapid Antigen Tests detect pathogen-specific proteins in clinical specimens, providing rapid results (minutes to hours) for conditions including strep throat, influenza, COVID-19, and others.

Serology detects antibodies produced in response to infection. IgM antibodies suggest recent infection, while IgG antibodies indicate past infection or immunity. Serology is useful for diagnosing infections where the organism is difficult to culture (syphilis, hepatitis, HIV).

Enzyme-Linked Immunosorbent Assay (ELISA) is a laboratory technique for detecting antibodies or antigens in clinical specimens, used for many infectious disease tests.

Western Blot confirms positive screening tests (like HIV ELISA) by detecting antibodies to specific pathogen proteins. Western blot provides greater specificity than screening tests.

Nucleic Acid Amplification Tests (NAATs) amplify pathogen DNA or RNA for detection, offering high sensitivity for many infections including chlamydia, gonorrhea, tuberculosis, and COVID-19.

Cancer Marker Testing

Tumor markers are substances (proteins, hormones, genes) produced by cancer cells or the body in response to cancer, used for screening, diagnosis, monitoring, and prognosis. Understanding tumor marker terminology helps patients appreciate the uses and limitations of these tests.

Prostate-Specific Antigen (PSA) is a protein produced by the prostate gland, elevated in prostate cancer, benign prostatic hyperplasia, and prostatitis. PSA is used for prostate cancer screening, monitoring treatment response, and detecting recurrence.

Carcinoembryonic Antigen (CEA) is a tumor marker associated with colorectal cancer and other adenocarcinomas. CEA is used for monitoring colorectal cancer treatment and detecting recurrence, though not for screening.

Cancer Antigen 125 (CA-125) is a tumor marker associated with ovarian cancer, elevated in endometriosis, pelvic inflammatory disease, and other conditions. CA-125 is used for monitoring ovarian cancer treatment and detecting recurrence.

Cancer Antigen 19-9 (CA 19-9) is a tumor marker associated with pancreatic cancer, elevated in pancreatic cancer, cholangiocarcinoma, and other gastrointestinal malignancies. CA 19-9 is used for monitoring pancreatic cancer treatment.

Alpha-Fetoprotein (AFP) is a tumor marker associated with hepatocellular carcinoma (liver cancer), testicular cancer, and germ cell tumors. AFP is used for screening high-risk patients, monitoring treatment, and detecting recurrence.

Human Chorionic Gonadotropin (hCG) is a hormone normally produced during pregnancy, elevated in gestational trophoblastic disease and some germ cell tumors. hCG is used for diagnosis and monitoring of these conditions.

Lactate Dehydrogenase (LDH) is an enzyme elevated in tissue damage, including cancer cell destruction. LDH is a prognostic marker in lymphomas and other malignancies.

Genetic and Molecular Testing

Genetic and molecular testing identifies inherited or acquired genetic changes, enabling diagnosis of genetic disorders, cancer classification, and personalized treatment selection. Understanding genetic terminology helps patients appreciate how these sophisticated tests guide medical care.

Chromosome Analysis (Karyotype) visualizes chromosomes under a microscope to detect large chromosomal abnormalities (aneuploidy, large deletions or duplications, translocations). Used for diagnosing Down syndrome, Turner syndrome, and other chromosomal disorders.

Fluorescence In Situ Hybridization (FISH) uses fluorescent probes to detect specific DNA sequences on chromosomes, identifying smaller abnormalities than karyotype. FISH is used for diagnosing specific chromosomal abnormalities in leukemia, lymphoma, and genetic syndromes.

Polymerase Chain Reaction (PCR) amplifies specific DNA sequences for detection and analysis. PCR is used for diagnosing infectious diseases, detecting genetic mutations, and testing for minimal residual disease in cancer.

Next-Generation Sequencing (NGS) rapidly sequences large portions of the genome, enabling comprehensive genetic analysis. NGS panels test multiple genes simultaneously, whole exome sequencing analyzes all protein-coding genes, and whole genome sequencing analyzes the entire genome.

BRCA1 and BRCA2 Testing identifies mutations in these tumor suppressor genes associated with hereditary breast and ovarian cancer syndrome. Positive results indicate high cancer risk and guide preventive strategies.

KRAS, NRAS, BRAF Testing identifies mutations in these genes that predict response to targeted therapies in colorectal cancer and other malignancies.

PD-L1 Testing measures PD-L1 expression on tumor cells, predicting response to immune checkpoint inhibitors in various cancers.

Imaging Terminology

Imaging studies provide visualization of internal structures, enabling diagnosis, staging, and monitoring of disease. Understanding imaging terminology helps patients appreciate what different studies show and why particular tests are ordered.

X-ray (Radiography) uses ionizing radiation to produce images of bones and some soft tissues. Chest X-rays evaluate lungs, heart, and bones; abdominal X-rays evaluate bowel gas patterns and some masses; extremity X-rays evaluate fractures and arthritis.

Computed Tomography (CT) uses X-rays from multiple angles to create cross-sectional images, providing detailed anatomical information. CT angiography (CTA) images blood vessels; CT colonography (virtual colonoscopy) images the colon; CT chest/abdomen/pelvis provides comprehensive evaluation.

Magnetic Resonance Imaging (MRI) uses magnetic fields and radio waves to create detailed images of soft tissues without ionizing radiation. MRI is superior to CT for brain, spinal cord, and musculoskeletal imaging. MR angiography (MRA) images blood vessels; MR cholangiopancreatography (MRCP) images biliary and pancreatic ducts.

Positron Emission Tomography (PET) uses radioactive glucose to image metabolic activity, distinguishing benign from malignant lesions and evaluating cancer spread. PET/CT combines metabolic and anatomical imaging.

Ultrasound uses high-frequency sound waves to create images, particularly useful for abdominal, pelvic, thyroid, and vascular imaging. Doppler ultrasound evaluates blood flow; echocardiography images the heart.

Bone Scan (Bone Scintigraphy) uses radioactive tracers to detect areas of increased bone turnover, identifying fractures, tumors, infection, and other abnormalities.

Mammography is specialized X-ray imaging of the breast, used for screening and diagnostic evaluation of breast abnormalities. Digital mammography and tomosynthesis (3D mammography) provide enhanced visualization.

Fluoroscopy provides real-time X-ray imaging, used for procedures like barium studies, angiography, and interventional radiology procedures.

Angiography images blood vessels using contrast injection, used for diagnosing and treating vascular disease (coronary angiography, cerebral angiography, peripheral angiography).

Endoscopic and Biopsy Terminology

Endoscopy and biopsy provide direct visualization and tissue sampling for diagnosis. Understanding this terminology helps patients appreciate what these procedures reveal and how they guide treatment.

Endoscopy uses a flexible or rigid scope to visualize internal organs. Upper endoscopy (EGD, esophagogastroduodenoscopy) examines esophagus, stomach, and duodenum; colonoscopy examines the colon; sigmoidoscopy examines the distal colon; bronchoscopy examines the airways; cystoscopy examines the bladder.

Biopsy removes tissue for microscopic examination. Incisional biopsy removes a portion of a lesion; excisional biopsy removes the entire lesion; needle biopsy (core needle, fine needle aspiration) removes tissue using a needle.

Pathology examines tissue samples microscopically to diagnose disease. Histopathology examines stained tissue sections; cytology examines individual cells (Pap smear, fine needle aspiration).

Staging determines the extent of cancer spread using the TNM system (Tumor size, Node involvement, Metastasis) or other staging systems. Understanding staging helps patients appreciate cancer prognosis and treatment options.

Frequently Asked Questions

What is the difference between CMP and BMP? The Comprehensive Metabolic Panel (CMP) includes 14 tests: the 8 tests in the Basic Metabolic Panel (BMP) plus total protein, albumin, alkaline phosphatase, AST, ALT, and bilirubin. The CMP provides more complete information about liver and nutritional status.

What does a high LDL cholesterol mean? LDL cholesterol is “bad cholesterol” that contributes to atherosclerosis. High LDL increases cardiovascular risk and typically requires lifestyle modification and often medication (statins) to reduce risk.

What does a low white blood cell count mean? Leukopenia (low WBC) may indicate viral infections, bone marrow disorders, autoimmune diseases, or medication effects. Very low WBC increases infection risk and requires evaluation.

What is the difference between HDL and LDL cholesterol? HDL is “good cholesterol” that removes cholesterol from arteries; LDL is “bad cholesterol” that deposits cholesterol in arteries. Higher HDL is protective; lower LDL reduces cardiovascular risk.

What does elevated PSA mean? Elevated PSA may indicate prostate cancer, benign prostatic hyperplasia (BPH), prostatitis, or other prostate conditions. Further evaluation (repeat testing, prostate MRI, biopsy) is needed to determine the cause.

What is the difference between Type 1 and Type 2 diabetes? Type 1 diabetes results from autoimmune destruction of insulin-producing beta cells, requiring insulin therapy. Type 2 diabetes results from insulin resistance and relative insulin deficiency, initially treated with oral medications and lifestyle changes.

What does a positive ANA test mean? Positive ANA may indicate autoimmune disease (lupus, Sjogren’s, scleroderma) but also occurs in healthy individuals and with other conditions. Titer, pattern, and clinical context determine significance.

What is the difference between CT and MRI? CT uses X-rays and is faster, less expensive, and better for bone imaging and acute conditions. MRI uses magnetic fields and provides better soft tissue detail, particularly for brain, spinal cord, and musculoskeletal imaging.

What is a PET scan? PET (positron emission tomography) images metabolic activity using radioactive glucose. PET/CT combines PET with CT for anatomical correlation, useful for cancer staging, detecting metastases, and evaluating treatment response.

What is high-sensitivity CRP? High-sensitivity CRP (hs-CRP) measures CRP at very low levels, used for cardiovascular risk assessment. Elevated hs-CRP suggests increased cardiovascular risk, particularly in patients with intermediate risk.

What does elevated liver enzymes mean? Elevated AST and ALT suggest liver cell injury from hepatitis, drugs, toxins, or other causes. Elevated ALP suggests cholestasis or bone disease. Pattern and clinical context guide further evaluation.

What is eGFR? eGFR (estimated glomerular filtration rate) calculates kidney function from creatinine, age, sex, and race. eGFR categorizes kidney function from normal (>90) through stages of chronic kidney disease to kidney failure (<15).

What is the difference between fasting and random glucose? Fasting glucose requires 8 hours without food, used for screening and diagnosis of diabetes. Random glucose can be tested anytime, used when fasting is impractical or for detecting significant hyperglycemia.

What is an MRI with contrast? Contrast (gadolinium) enhances visualization of blood vessels, tumors, and inflammation. Contraindicated in severe kidney disease due to risk of nephrogenic systemic fibrosis.

What is a biopsy? Biopsy removes tissue for microscopic examination, enabling definitive diagnosis of cancer and other conditions. Types include needle biopsy, incisional biopsy, and excisional biopsy.

What is the difference between CT and CT angiography? CT angiography (CTA) uses contrast injection specifically to image blood vessels, while standard CT may or may not use contrast for general imaging.

What does elevated troponin mean? Troponin is a protein released from damaged heart muscle. Elevated troponin indicates myocardial infarction (heart attack) or other cardiac injury, requiring urgent evaluation.

What is the difference between viral and bacterial infection testing? Viral infections are diagnosed by detecting viral genetic material (PCR), antigens (rapid tests), or antibodies (serology). Bacterial infections are diagnosed by culture, PCR for bacterial DNA, or sometimes antigen testing.

What is genetic testing used for? Genetic testing diagnoses inherited disorders, identifies cancer risk (BRCA), guides cancer treatment (KRAS, EGFR), and enables prenatal diagnosis of chromosomal abnormalities.

What does a positive pregnancy test detect? Home and laboratory pregnancy tests detect human chorionic gonadotropin (hCG), a hormone produced by the developing placenta after implantation.

What is the difference between screening and diagnostic tests? Screening tests are performed in asymptomatic individuals to detect disease early. Diagnostic tests are performed when symptoms are present to confirm or rule out specific diagnoses.

What does a high creatinine mean? Elevated creatinine indicates reduced kidney function (reduced glomerular filtration rate) or increased muscle breakdown. Further evaluation (eGFR, BUN, urinalysis) helps determine the cause and assess kidney function.

What is an endoscopy? Endoscopy uses a flexible scope to visualize internal organs (esophagus, stomach, colon, airways, bladder), enabling diagnosis and sometimes treatment of conditions in these organs.

What does elevated D-dimer mean? D-dimer is a fibrin degradation product elevated when blood clots are being broken down. Elevated D-dimer suggests possible deep vein thrombosis, pulmonary embolism, or other thrombotic condition, though it is nonspecific.

What is the difference between serum and plasma? Serum is the liquid portion of blood after clotting; plasma is the liquid portion with clotting factors intact. Most blood tests use serum; some tests (coagulation, certain specialized tests) require plasma.

What is a complete blood count with differential? CBC with differential includes the standard CBC (RBC, hemoglobin, hematocrit, platelet count) plus a breakdown of white blood cell types (neutrophils, lymphocytes, monocytes, eosinophils, basophils).

What does a positive rheumatoid factor mean? Positive rheumatoid factor occurs in 70-80% of rheumatoid arthritis patients but also in other autoimmune diseases, infections, and elderly individuals. Clinical context determines significance.

What is a lipid panel? Lipid panel measures total cholesterol, LDL, HDL, triglycerides, and sometimes VLDL, non-HDL cholesterol, or apolipoproteins. Used to assess cardiovascular risk and guide lipid-lowering therapy.

What is the difference between accuracy and precision in testing? Accuracy describes how close a test result is to the true value. Precision describes how reproducible test results are (repeat testing gives similar results).

What is therapeutic drug monitoring? Therapeutic drug monitoring measures drug levels to ensure they are in the therapeutic range (effective but not toxic). Used for medications like digoxin, lithium, phenytoin, and some immunosuppressants.

What is the normal range for blood tests? Normal ranges vary by laboratory, age, sex, and other factors. Results should be interpreted in the context of the reference range provided and clinical context.

Key Takeaways

Laboratory and diagnostic testing provides the objective data that underlies modern medical practice, enabling accurate diagnosis, effective treatment monitoring, and personalized healthcare. Understanding the terminology of diagnostic medicine—from basic blood tests (CBC, CMP, lipid panel) to advanced imaging (CT, MRI, PET) and genetic testing—empowers patients to interpret their test results, engage meaningfully with their healthcare providers, and appreciate the sophisticated science underlying modern diagnosis. Dubai’s healthcare system offers access to world-class diagnostic facilities, and understanding diagnostic terminology helps patients navigate this landscape and make informed decisions about their healthcare.

Related Glossary Terms

• Pathology Medical Terms - Understanding pathology suffixes
• Pharmacology and Medication Terminology - Drug-related terminology
• Cardiovascular Terminology - Heart and blood vessel terms
• Respiratory and Pulmonary Terminology - Respiratory terms

Schedule Your Diagnostic Consultation in Dubai

Understanding laboratory and diagnostic terminology helps you become a more informed participant in your healthcare journey. At Healer’s Clinic Dubai, our team of experienced healthcare professionals is dedicated to explaining your test results in clear, understandable language and guiding you through the diagnostic process. Whether you need routine health screening, specialized diagnostic testing, or interpretation of complex test results, our integrated approach combines conventional medicine with evidence-based complementary therapies to support your optimal health and wellbeing.

Contact our friendly team today to schedule your appointment and experience healthcare that puts your understanding and comfort first.

Important Medical Disclaimer: This glossary is provided for educational purposes only and should not be used as a substitute for professional medical advice, diagnosis, or treatment. Always consult with a qualified healthcare provider for medical concerns. If you are experiencing a medical emergency, please call emergency services or go to the nearest emergency department immediately.