A 43-yo woman complains of itching that keeps her awake

[quote="MCQ"]A 43-year-old woman complains of itching that keeps her awake at night. Physical examination is normal, except for the liver, which is felt 7 cm below the right costal margin. The blood count is normal; the results of serum chemistry tests are as follows: Creatinine
0.8 mg/dL Bilirubin
0.6 mg/dL Alanine aminotransferase
78 U/L Albumin
4.2 g/dL Alkaline phosphatase
450 U/L Which test would you order next in order to diagnose the underlying disorder?
A) Serum protein electrophoresis
(B) Anti?smooth-muscle antibody
(C) Antimitochondrial antibody
(D) Technetium-99m liver-spleen scan
(E) Endoscopic retrograde cholangiopancreatography (ERCP)[/quote] Answer: C Educational Objective: Recognize primary biliary cirrhosis and the most efficacious way of diagnosing it. This is the classic description of primary biliary cirrhosis. Itching is the most common specific symptom of early primary biliary cirrhosis. Approximately 70% of affected patients have enlarged livers. The best screening test for suspected primary biliary cirrhosis is the antimitochondrial antibody test. It is positive in 95% of affected patients and has a 98% specificity if newer enzyme-linked immunosorbent assay (ELISA) tests are used. Serum protein electrophoresis might show a diffuse increase in immunoglobulins. However, this finding is nonspecific and may be found in many chronic liver diseases. Anti?smooth-muscle antibody tests are positive in some patients with autoimmune chronic hepatitis. However, the test is nonspecific and not terribly useful. The sulfur colloid technetium liver-spleen scan is useful for detecting portal hypertension and hypersplenism. However, it is not specific and would not be helpful in diagnosing primary biliary cirrhosis. Endoscopic retrograde cholangiopancreatography (ERCP) is typically normal in patients with primary biliary cirrhosis. Its only role in the diagnosis of primary biliary cirrhosis is in the patient who presents with a similar syndrome but who has a negative antimitochondrial antibody test. ERCP would then be performed to look for other causes of disease such as primary sclerosing cholangitis.