Rosh Emergency Medicine Practice Test

In a case of suspected hepatitis, which laboratory study would confirm the diagnosis?

1. A. Abdominal ultrasound

2. B. Hepatitis B surface antigen and IgM hepatitis B core antibody

3. C. IgM hepatitis A antibodies

4. D. Serum aminotransferases

The correct answer is: C. IgM hepatitis A antibodies

The confirmation of hepatitis diagnosis particularly relies on serological tests that identify the specific viral cause. In cases of suspected hepatitis, the detection of IgM antibodies is crucial, as they indicate a recent infection. The presence of IgM hepatitis A antibodies is specifically associated with acute hepatitis A virus infection. This serological finding confirms that the patient has been recently infected with the hepatitis A virus, thus affirming a diagnosis of hepatitis due to this virus. While other laboratory studies such as hepatitis B surface antigen and IgM hepatitis B core antibody are important for diagnosing hepatitis B, and serum aminotransferases might indicate liver inflammation or damage, they do not specifically confirm a diagnosis of hepatitis in the same way that the presence of IgM hepatitis A antibodies does for hepatitis A. Therefore, the focus on IgM antibodies is critical in establishing the diagnosis of acute viral hepatitis.