Hepatic Function Panel

Total Protein measures the combined concentration of all proteins in the blood serum, primarily albumin and globulins. It provides a general indication of nutritional status, liver function (protein synthesis), kidney function (protein loss), and hydration. Abnormal levels usually prompt investigation of specific protein fractions (albumin, globulin types).

Serum Albumin is the most abundant protein in the blood, synthesized by the liver. It maintains oncotic pressure (keeping fluid in blood vessels), transports hormones, fatty acids, and drugs, and acts as an antioxidant and anti-inflammatory mediator. Low levels can indicate liver disease, kidney disease (loss in urine), malnutrition, chronic inflammation, or infection (negative acute phase reactant). High levels usually suggest dehydration.

Serum Globulin is a calculated value (Total Protein - Albumin) representing a diverse group of proteins, including immunoglobulins (antibodies) and carrier proteins. Elevated globulins can indicate chronic inflammation, infection, autoimmune diseases, or certain blood cancers (like multiple myeloma). Low levels are less common but might occur with immunodeficiency or protein loss. The Albumin/Globulin ratio (A/G Ratio) is often considered, with optimal > 1.5.

Albumin/Globulin Ratio is a calculated value (Albumin / Globulin) representing the ratio of albumin to globulin in the blood. It is often used to assess liver function and inflammation.

Total Bilirubin measures the sum of direct (conjugated) and indirect (unconjugated) bilirubin in the blood. Bilirubin is a yellowish pigment produced from the breakdown of heme (mostly from red blood cells). Elevated levels cause jaundice (yellowing of skin/eyes) and can indicate liver disease (impaired conjugation/excretion), bile duct obstruction, or increased RBC breakdown (hemolysis). Gilbert's syndrome is a common, benign cause of mild unconjugated hyperbilirubinemia.

Direct (Conjugated) Bilirubin measures the form of bilirubin that has been conjugated (made water-soluble) by the liver. Elevated direct bilirubin (>0.3-0.4 mg/dL or >20-25% of total) specifically points towards problems with bilirubin excretion from the liver or bile ducts, such as hepatitis, cirrhosis, gallstones, or bile duct obstruction, rather than problems with RBC breakdown or initial liver uptake/conjugation.

Indirect (Unconjugated) Bilirubin is calculated as Total Bilirubin minus Direct Bilirubin. It represents the bilirubin produced from heme breakdown before it is conjugated by the liver. Elevated indirect bilirubin (making up >75-80% of an elevated total bilirubin) typically indicates increased red blood cell destruction (hemolysis) or impaired liver uptake/conjugation (e.g., Gilbert's syndrome, neonatal jaundice, certain drugs).

Alkaline Phosphatase (ALP) is an enzyme found primarily in the liver (bile ducts), bone, intestines, and placenta. Elevated levels can indicate liver disease (especially cholestatic conditions affecting bile flow), bone disorders with increased bone turnover (e.g., Paget's disease, fractures, growing children, vitamin D deficiency), or, rarely, other causes. Isoenzyme testing can help determine the source (liver vs. bone).

Aspartate Aminotransferase (AST) is an enzyme found primarily in the liver, heart, skeletal muscle, and kidneys. Elevated serum AST levels often indicate liver cell damage (hepatitis, toxins, ischemia) but can also rise due to muscle injury (including heart attack) or hemolysis. Its interpretation requires context, often alongside ALT (ALT is more liver-specific).

Alanine Aminotransferase (ALT) is an enzyme found predominantly in liver cells. Elevated serum ALT is a more specific indicator of liver cell injury or inflammation (hepatitis, fatty liver disease, drug toxicity) than AST. Consistently maintaining ALT in the lower end of the reference range is associated with better liver health.