Lab Tests Reference Library

ALT is a liver enzyme that leaks into the blood when liver cells are damaged. It is the most specific marker for liver damage, elevated in hepatitis, fatty liver, and drug-induced liver injury.

AST is found in liver, heart, and muscle cells. Elevated AST suggests liver damage, heart attack, or muscle injury. AST:ALT ratio helps differentiate alcoholic vs non-alcoholic liver disease.

ALP is an enzyme found in liver, bone, kidneys, and intestines. Elevated ALP suggests bile duct obstruction, bone disorders, or liver disease.

GGT is an enzyme primarily found in the liver. Elevated GGT is sensitive for liver and bile duct disease and is a marker for excessive alcohol consumption.

Bilirubin is a breakdown product of hemoglobin. Elevated total bilirubin causes jaundice and indicates liver disease, bile duct obstruction, or increased red cell destruction (hemolysis).

Albumin is the main protein made by the liver. Low albumin (hypoalbuminemia) indicates chronic liver disease, malnutrition, or kidney protein loss.

Creatinine is a waste product from muscle metabolism filtered by the kidneys. Elevated creatinine indicates impaired kidney function.

BUN measures the amount of nitrogen from urea in blood. Elevated BUN can indicate kidney disease, dehydration, high protein diet, or GI bleeding.

eGFR estimates how well kidneys filter waste from blood. It is calculated from creatinine, age, and sex. eGFR <60 for 3+ months defines chronic kidney disease (CKD).

Uric acid is a breakdown product of purines. Elevated uric acid (hyperuricemia) causes gout and kidney stones. Low levels may suggest certain genetic disorders.

Sodium is the primary extracellular electrolyte controlling fluid balance. Abnormal sodium causes neurological symptoms. Critical for cardiac and brain function.

Potassium is essential for heart rhythm, muscle contraction, and nerve function. Both low (hypokalemia) and high (hyperkalemia) levels are potentially life-threatening.

Chloride is the main extracellular anion, essential for fluid and acid-base balance. Usually measured as part of electrolyte panels.

Fasting blood glucose is measured after at least 8 hours of fasting. It is the primary test for diagnosing diabetes and pre-diabetes.

HbA1c reflects average blood glucose over the past 2–3 months. It is the gold standard for diabetes monitoring and diagnosis. Each 1% increase above 6.5% significantly increases complication risk.

Total cholesterol is the sum of all cholesterol types in blood. Elevated total cholesterol increases cardiovascular disease risk.

LDL ("bad" cholesterol) deposits on artery walls causing atherosclerosis. Lowering LDL is the primary target of cardiovascular risk reduction therapy.

HDL ("good" cholesterol) removes cholesterol from arteries and transports it to the liver. Higher HDL levels are protective against heart disease.

Triglycerides are fats stored in fat cells and carried in blood. Elevated triglycerides increase pancreatitis and cardiovascular risk, often linked to diabetes and obesity.

Troponin is released from heart muscle cells when they are damaged. It is the most specific marker for myocardial infarction (heart attack). High-sensitivity troponin detects minor heart damage.

CK-MB is a heart-specific form of creatine kinase. Elevated CK-MB suggests heart muscle damage. Used alongside troponin for diagnosis of myocardial infarction.