Antihypertensives: alpha-methyldopa: practice question

A Pharmacology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Pharmacology · Antihypertensives: alpha-methyldopa

Sample item

A 30-year-old woman at 28 weeks of pregnancy has been on alpha-methyldopa for chronic hypertension for five months. She now has fatigue and pallor, with haemoglobin 7.8 g/dL, raised indirect bilirubin and reticulocytosis. Which finding is most likely?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

C. Autoimmune haemolytic anaemia with a positive direct Coombs test

Alpha-methyldopa is converted to alpha-methylnoradrenaline, a false transmitter that stimulates central alpha2 receptors and reduces sympathetic outflow. It is safe in pregnancy but can provoke a drug-induced autoimmune haemolysis, and a positive direct Coombs test occurs in a substantial minority of long-term users. Hepatitis and sedation are other adverse effects.

Option by option

  • A. Megaloblastic anaemia from impaired folate absorption

    Megaloblastic anaemia from folate deficiency is not a feature of methyldopa and would not cause raised indirect bilirubin with reticulocytosis.

  • B. Methaemoglobinaemia with chocolate-brown blood

    Methaemoglobinaemia is caused by oxidant drugs such as dapsone or nitrites, not methyldopa.

  • C. Autoimmune haemolytic anaemia with a positive direct Coombs test (correct)

    Correct. Methyldopa can induce red-cell autoantibodies, giving a Coombs-positive haemolytic anaemia.

  • D. Haemolysis from G6PD deficiency with Heinz bodies and a negative Coombs test

    G6PD haemolysis is oxidant-triggered and Coombs-negative, which does not fit this drug.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Pharmacology question

What is the answer to this Pharmacology question?

The best answer is C, Autoimmune haemolytic anaemia with a positive direct Coombs test. Alpha-methyldopa is converted to alpha-methylnoradrenaline, a false transmitter that stimulates central alpha2 receptors and reduces sympathetic outflow.

Why is "Megaloblastic anaemia from impaired folate absorption" not the answer?

Megaloblastic anaemia from folate deficiency is not a feature of methyldopa and would not cause raised indirect bilirubin with reticulocytosis.

Why is "Methaemoglobinaemia with chocolate-brown blood" not the answer?

Methaemoglobinaemia is caused by oxidant drugs such as dapsone or nitrites, not methyldopa.

Why is "Haemolysis from G6PD deficiency with Heinz bodies and a negative Coom…" not the answer?

G6PD haemolysis is oxidant-triggered and Coombs-negative, which does not fit this drug.

What concept does this question test?

It tests Antihypertensives: alpha-methyldopa in Pharmacology. It is safe in pregnancy but can provoke a drug-induced autoimmune haemolysis, and a positive direct Coombs test occurs in a substantial minority of long-term users. Hepatitis and sedation are other adverse effects.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Antihypertensives: alpha-methyldopa?

Learn drugs as classes, then the exception in each class that an examiner would pick. Then use the flashcards and the other Pharmacology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.