virology -5 - shiney

[ArchivalUser]

pregnant southeast Asian immigrant presents for prenatal care. Her past medical history is significant
for a severe illness 3 years ago characterized by fatigue, nausea, anorexia, vomiting, jaundice,
joint pains, and generalized skin lesions that slowly disappeared. She has felt well recently.
Which of the following laboratory tests should be ordered to investigate the patient's past
illness?

A. Hepatitis B surface antigen (HBsAg)

B. IgG cytomegalovirus (CMV) antibody levels

C. IgM antibody to HBsAg

D. IgM antibody to hepatitis B core antigen

E. Quantitation of hepatitis A virus (HAV) IgM antibody

[ArchivalUser]

cc?

[ArchivalUser]

noo

[ArchivalUser]

bb

[ArchivalUser]

no! one more try

[ArchivalUser]

okay here is the answer,
The correct answer is A. The clinical signs suggest that this woman had hepatitis B three years
ago and the fact that she is now feeling better also suggests that she recovered from this
infection. Since she is pregnant, it is necessary to find out if she still has the organism in
her liver (chronic hepatitis B infection) by performing a test for HBsAg. This test will be
negative if she has completely recovered from the disease, but it would be positive if she is a
chronic carrier.

The clinical signs of the disease she had 3 years ago do not match those of CMV (choice B), and
CMV does not produce chronic infections.

Measurement of IgM antibody to hepatitis B core antigen (choice D) would be of no value at this
time. This antibody is positive in acute cases of hepatitis B, but would no longer be positive
in this case. Measurement of IgM anti-hepatitis B core antigen is one of the most important
tests in the hepatitis profile because the appearance of the antibody correlates with the
disappearance of HBsAg.

Examination of IgM antibody to HBsAg (choice C) would be of no value at this time. This IgM
antibody would be formed early during the recovery from acute hepatitis B, and would class
switch to IgG later on in the disease.

Quantitation of hepatitis A virus (HAV) IgM antibody (choice E) would be useless, since
hepatitis A virus (HAV) only causes acute infectio

[ArchivalUser]

nice explanation Shiney thanks...

[ArchivalUser]

welcome!!