Saturday, August 21, 2010

Serum Bilirubin

Serum Bilirubin


      Spectrophotometric determinations of serum bilirubin in clinical laboratory measures two pigment fractions: (1) The water soluble conjugated fraction that gives a direct reaction with diazo reagent and consist largely of conjugated bilirubin. (2) The lipid soluble indirect – reaction fraction that represents primarily unconjugated bilirubin.


Differential diagnosis of disease of hepatobiliary system and pancreas and other

Causes of jaundice.


Normal levels

Total bilirubin

Direct bilirubin

   0.1 – 1.2 mg/dL

  0.03 – 0.5 mg/dL


Increased in

Direct (conjugated) Bilirubin in

20 -40% of total: more suggestive of hepatic than posthepatic jaundice, 40 -60% of total: occur in either hepatic or posthepatic; > 50% of total: more suggestive of posthepatic than hepatic jaundice; total serum bilirubin > 40mg/dl indicates hepatocellular rather than extrahepatic obstruction.


·        Hereditary disorders (e.g. Dubin Johnson syndrome, Rotor's syndrome)

·        Biliary duct obstruction (extra and intrahepatic)

·         Hepatic cellular damage (viral, toxic, alcohol/ drug related)

·        Infiltration, space – occupying lesions (e.g. metastatic tumor, abscess, granulomas)

  Increased unconjugated (indirect) bilirubin in

Increased bilirubin production; hemolytic diseases (e.g. hemoglobinopathies, RBC enzyme deficiencies, disseminated intravascular coagulation (DIC), autoimmune hemolysis); ineffective erythropoiesis; blood transfusions; hematomas; hereditary disorders (e.g. Gilbert's disease, Crigler – Najjar syndrome); drugs causing hemolysis.

Tuesday, August 17, 2010

Uric Acid

1.      Uric Acid



Uric acid levels are very labile and show day to day and seasonal variation in same person, also increased by emotional stress, total fasting, increased body weight, uric acid levels that do not correlate with the severity of kidney damage; urea and Creatinine are better.


Monitor chemotherapeutic treatment of neoplasms to avoid renal urate deposition with possible renal failure; monitor treatment of gout.  


Normal Levels



         1 –3 years

    4.0 – 8.6 mg/dL

        3 – 5.9 mg/dL

         1. 8 -5

Increased in

Renal failure; gout and also in 25% of relatives of patients of gout; asymptomatic hyperuricemia; leukemia, multiple myeloma, malignancies, lymphoma and other disseminated neoplasm and cancer chemotherapy; hemolytic and sickle cell anemia; toxemia of pregnancy; psoriasis (1/3 cases); drug use (barbiturates, methyl alcohol, salicylates, thiazides, furosemide, mitomycin, levodopa, phenytoin sodium); metabolic acidosis; diet (high protein, weight reduced diet). 


Others von Gierke's disease, lead poisoning, Down's syndrome, polycystic kidney disease, atherosclerosis and hypertension (serum uric acid is increased in 80% of patients with elevated serum triglycerides).

Decreased in

Drugs (adrenocorticotropic hormone [ ACTH], high dose salicylates, probenecid, cortisone); Wilson's disease, Fanconi's syndrome, celiac disease, xanthuria




Serum Creatinine is the most specific and sensitive indicator of renal disease. Use of BUN and Creatinine levels together is more informative in renal disorders.


Normal Range





 0.7 - 1.4 mg/dL

  0.6 – 1.1 mg/dL

   0.4 – 0.9 mg/dL

0.4 – 0.6 mg/dL



       Diagnosis of renal insufficiency


Increased in

Diet [ingestion of Creatinine (roast meat); prerenal azotemia; postrenal azotemia; impaired kidney function, 50% of renal function is needed to increase serum Creatinine from 1.0 – 2.0mg/dl. Therefore, not sensitive to mild – to moderate renal injury.

Decreased in

Pregnancy – normal value is 0.4 – 0.6 mg/dL. > 0.8mg/Dl is abnormal and should alert clinician to further diagnostic evaluation.