Which laboratory test is most important to monitor regularly in a patient taking azathioprine?

Which laboratory test is most important to monitor regularly in a patient taking azathioprine?

• A. Liver function tests
• B. Blood urea nitrogen
• C. Complete blood count
• D. Serum electrolytes

Answer: (C)

Azathioprine can suppress bone marrow, reducing the production of all blood cells. The most important lab to monitor is a complete blood count because it directly shows bone marrow function and can detect neutropenia, anemia, or thrombocytopenia early. Catching these cytopenias promptly lets you adjust the dose or stop the medication to prevent serious infections or bleeding. Liver function tests are also monitored since hepatotoxicity can occur, but changes in the CBC provide the primary safety signal. Other labs like BUN or electrolytes don’t specifically reflect azathioprine toxicity.

Azathioprine can suppress bone marrow, reducing the production of all blood cells. The most important lab to monitor is a complete blood count because it directly shows bone marrow function and can detect neutropenia, anemia, or thrombocytopenia early. Catching these cytopenias promptly lets you adjust the dose or stop the medication to prevent serious infections or bleeding. Liver function tests are also monitored since hepatotoxicity can occur, but changes in the CBC provide the primary safety signal. Other labs like BUN or electrolytes don’t specifically reflect azathioprine toxicity.