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Table 28-2.
Differential diagnosis of jaundice based on laboratory tests. |
| Body_ID: None |
| Differential diagnosis of jaundice |
| Body_ID: T028002.50 |
| Test | Prehepatic | Intrahepatic | Posthepatic |
| Body_ID: T028002.100 |
| Conjugated bilirubin | absent | increased | increased |
| Body_ID: T028002.150 |
| AST or ALT | normal | increased | normal |
| Body_ID: T028002.200 |
| ALP | normal | normal | increased |
| Body_ID: T028002.250 |
| Urine bilirubin | absent | present | present |
| Body_ID: T028002.300 |
| Urine urobilinogen | present | present | absent |
| Body_ID: T028002.350 |
|
| Body_ID: T028002.400 |
|
| Body_ID: T028002.450 |
The reference ranges for liver function tests are as follows: AST (aspartate aminotransferase) 5-45U/L, ALT (alanine aminotransferase) 5-40U/L, ALP (alkaline phosphatase) 50-260 (ALP is physiologically elevated in children and adolescents).
Bilirubin <17μmol/L (<1.0mg/dL), Albumin 35-45g/L (3.5-4.5g/dL), γ-glutamyl transpeptidase: men <90 U/L, women <50 U/L. See also box on p. 422.
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Table 28-3.
Causes of jaundice. |
| Body_ID: None |
| The causes of jaundice |
| Body_ID: T028003.50 |
| Type | Cause | Clinical example | Frequency |
| Body_ID: T028003.100 |
| Prehepatic | hemolysis | autoimmune | uncommon |
| Body_ID: T028003.150 |
| | | abnormal hemoglobin | depends on region |
| Body_ID: T028003.200 |
| Intrahepatic | infection | hepatitis A, B, C | common/very common |
| Body_ID: T028003.250 |
| | chemical/drug | acetaminophen | common |
| Body_ID: T028003.300 |
| | | alcohol | common |
| Body_ID: T028003.350 |
| | genetic errors: | Gilbert's syndrome | 1 in 20 |
| Body_ID: T028003.400 |
| | bilirubin | Crigler-Najjar syndrome | very rare |
| Body_ID: T028003.450 |
| | metabolism | Dubin-Johnson syndrome | very rare |
| Body_ID: T028003.500 |
| | | Rotor's syndrome | very rare |
| Body_ID: T028003.550 |
| | genetic errors: | Wilson's disease | 1 in 200 000 |
| Body_ID: T028003.600 |
| | specific proteins | α1 antitrypsin | 1 in 1000 with genotype |
| Body_ID: T028003.650 |
| | autoimmune | chronic active hepatitis | uncommon/rare |
| Body_ID: T028003.700 |
| | neonatal | physiologic | very common |
| Body_ID: T028003.750 |
| Posthepatic | intrahepatic bile | drugs | common |
| Body_ID: T028003.800 |
| | ducts | primary bilary cirrhosis | uncommon |
| Body_ID: T028003.850 |
| | | cholangitis | common |
| Body_ID: T028003.900 |
| | extrahepatic bile | gall stones | very common |
| Body_ID: T028003.950 |
| | ducts | pancreatic tumor | uncommon |
| Body_ID: T028003.1000 |
| | | cholangiocarcinoma | rare |
| Body_ID: T028003.1050 |
| Aspartate amino transferase (AST) and alanine transaminase (ALT) are involved in the interconversion of amino and ketoacids, and are therefore required for hepatic metabolism of nitrogen and carbohydrates. Both these transaminases are located in the mitochondria; ALT is also found in the cytoplasm. The serum activity of ALT is a better marker of liver disease than that of AST, which is also present in muscle and red blood cells. In more severe liver disease, the synthetic functions of the hepatocytes are likely to be affected, and so
the patient would be expected to have a prolonged prothrombin time and low serum albumin concentration.
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