A 40 Year old patient presenting with nausea, vomiting and abnormal liver function tests...

A 40-year-old school teacher develops nausea and vomiting at the beginning of the fall semester. Over the summer she had taught preschool children in a small town in Mexico. She is sexually active, but has not used intravenous drugs and has not received blood products.
Physical examination reveals scleral icterus, right upper quadrant tenderness, and a palpable liver. Liver function tests show aspartate aminotransferase of 750 U/L (normal < 40) and alanineaminotransferase of 1020 U/L (normal < 45). The bilirubin is 13 mg/dL (normal < 1.4) and the alkaline phosphatase is normal.

What further diagnostic test is most likely to be helpful?
a. Liver biopsy
b. Abdominal ultrasound
c. IgM antibody to hepatitis A
d. Antibody to hepatitis B surface antigen
e. Determination of hepatitis C RNA

Answer:
C: IgM antibody to hepatitis A

Discussion: This patient has evidence for acute hepatitis as is suggested by the history, physical examination and laboratory data showing hepatocellular injury.
The epidemiology favors acute hepatitis A; the patient’s history of travel to Mexico and work as a teacher are risk factors for hepatitis A. The incubation period of about one month is also typical.

Hepatitis B and C are less likely without evidence for drug abuse or blood transfusion. Antibody to hepatitis B surface antigen would not be evidence for acute hepatitis B.

HCV RNA is the appropriate test for acute hepatitis C infection, but this disease typically causes mild transaminase elevation and rarely presents with icterus..

Liver biopsy is not indicated in acute hepatitis as the diagnosis is usually apparent from the examination, liver enzymes, and serological evidence of recent viral infection.

Abdominal ultrasound would not be helpful as liver enzymes suggest hepatocellular damage, not biliary obstruction