Azathioprine treatment and mate fertility in inflammatory bowel disease

Background & Aims: Long-term treatment with azathioprine (AZA) is well esta blished in inflammatory bowel disease (IBD). AZA is metabolized to 6-mercap topurine (6-MP), which interacts in purine metabolism and is therefore cons idered to have mutagenic potentials. This is the first study to examine the influence of AZA on semen quality. Methods. Semen quality was examined and compared with World Health Organization (WHO) standards regarding sperm de nsity, motility, morphology, ejaculate volume, and total sperm count in 23 IBD patients treated with AZA. In 10 of these patients, a semen sample was assessed before and during AZA treatment; in another 5, semen analysis was performed twice during at least 2 years of AZA therapy. Results: In 18 pati ents treated with 1.5-2 mg/kg AZA daily for at least 3 months but without s ulfasalazine,- sperm density was 94 +/- 84 Mio/mL (94% within WHO standard) , motility was 60% +/- 20% (67% within WHO standard), the proportion of spe rm with normal morphology was 44% +/- 21% (67% within WHO standard), ejacul ate volume was 3.4 +/- 1.5 mL (89% within WHO standard), and, total sperm c ount was 297 +/- 272 Mio (94% within WHO standard). No changes in semen par ameters were noted after 11 +/- 5 months of AZA administration or during lo ng-term treatment (49 +/- 14 months). Sulfasalazine administration in 5 pat ients was associated with markedly reduced semen morphology. During the stu dy period, 6 patients fathered 7 healthy children. Conclusions: Our data sh ow that AZA does not reduce semen quality and thereby male fertility in, IB D.