Test your medicine knowledge with the MKSAP challenge, in partnership with the American College of Physicians.

A 25-year-old man is evaluated after being turned down as a blood donor because of abnormal liver chemistry tests. The patient is healthy, takes no medications, does not smoke, and drinks alcohol socially. His parents and siblings are alive and healthy; his maternal grandfather developed type 2 diabetes mellitus at age 75 years. The review of systems is normal.

On physical examination, vital signs and BMI are normal.

Laboratory studies:

Hemoglobin	11.9 g/dL (119 g/L)
Mean corpuscular volume	76 fL
Cholesterol (total)	155 mg/dL (4.01 mmol/L)
LDL cholesterol	85 mg/dL (2.2 mmol/L)
HDL cholesterol	33 mg/dL (0.85 mmol/L)
Bilirubin (total)	0.5 mg/dL (8.55 µmol/L)
Aspartate aminotransferase	25 U/L
Alanine aminotransferase	58 U/L
Alkaline phosphatase	110 U/L

Serologic tests for hepatitis virus infection are normal.

Which of the following is the most appropriate diagnostic test for this patient?

A) Anti-tissue transglutaminase antibody
B) α₁-Antitrypsin concentration
C) Blood alcohol level
D) Liver biopsy

MKSAP Answer and Critique

The correct answer is A) Anti-tissue transglutaminase antibody. This item is available to MKSAP 15 subscribers as item 45 in the Gastroenterology section.

MKSAP 16 released Part A on July 31. More information is available online.

Celiac disease is a small-bowel disorder characterized by mucosal inflammation, villous atrophy, and crypt hyperplasia, which occur on exposure to gluten. The disease is rather common, affecting nearly 1% (1/133 persons) of the population. Although many affected patients have diarrhea and steatorrhea, as well as bloating, abdominal pain, and malabsorption of vitamins and minerals, other patients are asymptomatic at diagnosis. Such patients may be found to have anemia or osteoporosis as part of routine health maintenance testing. Still others present with neurologic symptoms, dermatitis herpetiformis, or elevated concentrations of liver enzymes. The elevated alanine aminotransferase in this patient should normalize with a gluten-free diet if he has celiac disease. The patient’s elevated alkaline phosphatase concentration is likely the result of increased bone turnover as a result of vitamin D and calcium malabsorption. Celiac disease is one of the most common causes of osteoporosis in men. Measurement of serum anti-tissue transglutaminase antibodies has a sensitivity and specificity of approximately 90% for celiac disease.

α₁-Antitrypsin deficiency affects approximately 1 in 1600 persons, and although measurement of α₁-antitrypsin is an appropriate test in the work-up of abnormal liver function tests, it is not the next best test because of the low prevalence of the disease compared to celiac disease, and it cannot explain the patient’s anemia. The patient admits to social use of alcohol, and this is to be strictly avoided in the setting of liver disease. Unless the patient was actively drinking alcohol around the time of the testing, measuring the blood alcohol would not be helpful. Furthermore, in alcoholic liver disease, the aspartate aminotransferase concentration is usually greater than the alanine aminotransferase. Liver biopsy would be an extreme measure to take as a result of a mildly abnormal set of liver chemistry tests and is not indicated as an initial step.

Key Point

• Measurement of serum anti-tissue transglutaminase antibodies has a sensitivity and specificity of approximately 90% for celiac disease.

Learn more about ACP’s MKSAP 16.

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