Abnormal Liver Tests

Abnormal liver tests in hepatocellular injury or cholestasis

• Aminotransferases (AST. ALT): intracellular enzymes released 2' necrosis inflammation

ALT more specific for liver than is AST (also in heart, skeletal muscle, kidney, brain) ALT AST -» viral hepatitis or fatty liver nonalcoholic stcatohepatitis (pericirrhotic) AST:ALT -2:1 — alcoholic hepatitis; fit LDH ischemic or toxic hepatitis

• Alkaline phosphatase (A«j.): enzyme bound in hepatic canicular membrane besides liver, also found in bone, intestines, kidney, and placenta confirm liver origin with: T 5'-NT.' GGT. or A.«, heat fractionation t levels seen with biliary obstruction or intrahepatic cholestasis (eg, hepatic infiltration)

Tests of hepatic function

• Albumin: marker for liver protein synthesis, I slowly in liver failure (tin -20 d)

• Prothrombin time (PT): depends on synthesis of coag factors; because tin of some of these factors (eg,V, VII) is short. * PT can occur w/in h of liver dysfxn

• Bilirubin: product of heme metab. in liver; unconjugated (indirect) or conjugated (direct)

T conjugated can be from obstruction (intra extra-hepatic) or congenital disorder

I Patterns in liver injury

• Hepatocellular " aminotransferases. • T bilirubin or A.j>

Tit aminotransferases ( 1000): severe viral hepatitis, acetaminophen, ischemia

• Cholestasis: T1 At. and bilirubin. • * aminotransferases

• Isolated hyperbilirubinemia: TT bilirubin, normal A}» and aminotransferases

• Jaundice is a clinical sign seen when bilirubin -2.5 mg dl (especially in sclera or under tongue); if hyperbilirubinemia conjugated — t urine bilirubin

• Infiltrative: T - t bilirubin or aminotransferases

Figure 3-4 Approach to abnormal liver tests with hepatocellular pattern

Hepatocellular Injury

viral markers i auloAbs

tox screen

obesity. DM

hyperlipidemia *

viral markers i auloAbs

tox screen

Viral

Auto

Drugs &

hepatitis

immune

alcohol acetaminophen meds. toxins obesity. DM

hyperlipidemia *

hypotension

systemic

CHF

disease

t

*

| Vascular |

| Hereditary |

ischemic

hemochrom

congestive

u,ATdefic

Budd Chian

Wlson's

SOS

celiac sprue

Figure 3-5 Approach to abnormal liver tern with cholestatic pattern

Cholestasis

G ductal dilatation

Hepatocellular dysfunclion

hepatitis tf AIT) cirrhosis (tPT. ion»

meds

sepsis, post-op PBC

Biliary epitholial

intrahepatic

Biliary

damage

cholestasis

obstruction

hepatitis tf AIT) cirrhosis (tPT. ion»

meds

sepsis, post-op PBC

choledochoiithiasis cholangiocarcinoma pancreatic cancer sclerosing cholangitis

Isolated hyperbilirubinemia

unconjugated

I Overproduction |

Hemolysis (<4 mo«tf) Ineffective erythropoiesis Hematoma reabsorpt'on PE

Gilbert's (<5 max») Crigler-Najjar conjugated

Defective

Defective

conjugation

excretion

Dubin-Johnson Rotors Abnl biliary transport protein

Figure 3-7 Approach to abnormal liver teiu with infiltrative pattern

Infiltrative pattern

Sarcoidosis Histoplasmosis

Sarcoidosis Histoplasmosis

Amoebic Bacterial

Medications Idiopathic

Abnormal liver tests in asymptomatic patients (nejm 2000:342.1266)

• Hepatocellular evaluate for most common causes: alcohol. NAFLD. HBV HCV. hemochromatosis, meds

(NSAIDs. statins, abx) if unrevealing - rule out nonhepatic causes (✓ CPK.aldolase.TFTs) if hepatic — consider less common causes: autoimmune hepatitis. Wilson's disease.

celiac disease. «1-antitrypsin deficiency if unrevealing — liver biopsy if ALT or AST -2 x ULN for >6 mos: o w observe

• Cholestatic: / 5'-NT or GGT. if t - ✓ RUQ U S. AMA

careful review of med list — eliminate potential cholestatic meds if biliary dilatation or obstruction — ERCP MRCP to eval for choledocholithiasis or stricture liver biopsy if AMA © and U S ©, or AMA © and U S w abnormal parenchyma ^^ if AMA & U S ©: A* 1.5 ULN - consider biopsy. A* <1.5 ULN observe

• Isolated hyperbilirubinemia: ✓ conjugated vs. unconjugated conjugated perform abdominal US-» MRCP and or ERCP if dilatation or obstruction unconjugated -» ✓ hct. retic count, smear. LDH. haptoglobin

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