Hydroxyurea therapy: a rare cause of reversible azoospermia.

Background: Essential thrombocythaemia (ET) is an uncommon chronic myeloproliferative disorder characterized by a marked increase in the number of platelets. Hydroxyurea is effective in preventing thrombosis in high-risk patients with essential thrombocythaemia. In previous studies different side effects of Hydroxyurea have been pointed out, but attention has not really been focused on the possible side effects on spermatogenesis.
Case: A 35-year-old man under investigation for haematospermia and complaining of erythromyalgia was found to have a thrombocytosis with a platelet count of 1130 x 10(9)/l. Bone marrow aspiration confirmed a diagnosis of essential thrombocythaemia. He was commenced on hydroxyurea (2 g daily) in order to lower his platelet count and relieve the erythromyalgia. The patient represented to the urologists, 3 years later with infertility and a semen analysis done by his doctor had shown azoospermia. Monthly sperm counts after the withdrawal of hydroxyurea showed a gradual return of the spermatogenesis to normal over a period of around 6 months. The patient's wife had conceived within 4 months of him stopping hydroxyurea.
Conclusion: This case highlights a very rare but nonetheless important side effect of treatment with hydroxyurea. Hydroxyurea can cause reversible inhibition of spermatogenesis and result in primary infertility. We believe that all patients being commenced on such treatment should be warned of this possibility and that they should be given the necessary follow-up investigations.