Blood urea

Why is the test done? The blood urea test is used mainly to test the renal (kidney) function. In kidney diseases, there is an increase in the blood urea level due to reduced excretion by the kidneys. What is urea? In protein metabolism, urea is formed in the liver as the end product. Protein is broken down to amino acids during digestion. Amino acids contain nitrogen that is split off as the ammonium ion (NH4). The ammonium ion combines with other small molecules to produce urea. The urea is passed into the blood and excreted by the kidneys in the urine. Blood urea levels go up in most kidney diseases as urea excretion is affected. It may also be high in patients with liver disease or dehydration. A large number of drugs increase blood urea level by competing with it for excretion by the kidneys. How is the test done? Blood is drawn from a vein by venepuncture, usually from the inside of the elbow. No special preparation is required for the test. What are the normal values? 7 to 20 mg/dl What are the abnormal results? More-than-normal values could be due to: Kidney diseases like glomerulonephritis, pyelonephritis, and acute tubular necrosis Renal (kidney) failure Too much protein breakdown like in starvation Very high protein intake Congestive heart failure Heart Attack Bleeding in the gut Decrease in the blood volume like in burns, dehydration or shock Obstruction in the urinary tract due to a tumour, stones, or prostatic hypertrophy Drugs used in gout, infections, epilepsy, blood pressure, pain relief, etc may raise blood urea. These include allopurinol, aminoglycosides, cephalosporins, chloral hydrate, furosemide, indomethacin, methotrexate, methyldopa, drugs toxic for the kidneys (like high doses of aspirin, amphotericin B, carbamazepine, colistin, penicillamine, polymyxin B, probenecid, vancomycin), propranolol, rifampin, spironolactone, tetracyclines, thiazide diuretics, and triamterene Lower-than-normal levels may be due to: Low protein diet, malnutrition or too much fluid intake Liver failure Drugs to treat some infections like chloramphenicol and streptomycin

Liver blood tests

A series of special blood tests can often determine whether or not the liver is functioning properly. These tests may also distinguish between acute and chronic liver disorders and between hepatitis and cholestasis (bile obstruction). The most commonly performed blood tests include: Serum Bilirubin - Elevated levels of bilirubin often indicate an obstruction of bile flow or a defect in the processing of bile by the liver. Bilirubin is produced by the liver and is excreted in the bile. Serum Albumin - Below-normal levels of albumin, a protein made by the liver, are associated with many chronic liver disorders and cirrhosis.

Serum Alkaline Phosphatase - Elevated levels of alkaline phosphatase, an enzyme found in the bile, usually indicate an obstruction of bile flow, liver injury, or certain cancers.

Serum Aminotransferases (transaminases, SGOT, SGPT) - These enzymes are released from damaged liver cells. They include ALT (SGPT) and AST (SGOT). They (especially ALT) are elevated in hepatitis.

Prothrombin Time (PT) - This test measures the time it takes for blood to clot. Blood clotting requires vitamin K and a protein (prothrombin) made by the liver. Liver cell damage and bile flow obstruction can both interfere with proper blood clotting.
Gamma-glutamyl Transpeptidase (GGT) - This enzyme is released into the blood when the liver is damaged especially by alcohol or in bile obstruction.
Alpha-fetoprotein (AFP) - This protein is produced by the fetal liver and testes, indicating hepatitis or cancer.
Mitochondrial Antibodies (AMA) - The presence of these antibodies can indicate primary biliary cirrhosis, chronic active hepatitis, and certain other autoimmune disorders.
Virus tests

- HAV IgM, HEV IgM - these detect active infection by Hepatitis A or E virus
- HCV-Ab - this detects evidence of infection by HCV virus
- HCVRNA - this detects the actual presence of HCV virus
- HBsAg, HBeAg, HBV DNA - these detect infection with Hepatitis B virus (HBV)
- Anti-HBs - the evidence of good immunity to HBV infection