The decline of 6-thioguanine nucleotides is not linked to impaired efficacy or safety of thiopurines in pregnant women with inflammatory bowel disease

Monitoring of thiopurine metabolites (6-TGN, 6-MMPR) during pregnancy; the *TPMT* pathway governs the balance between efficacy (6-TGN) and toxicity (6-MMPR)

This Dutch retrospective cohort study (87 women, 100 pregnancies) examines thiopurine metabolite changes during pregnancy in patients with inflammatory bowel disease. A significant reduction in 6-thioguanine nucleotides (6-TGN) occurs in the second and third trimesters, but without association with increased disease activity (fecal calprotectin). No significant increase in 6-MMPR is observed, and toxicity markers remain stable. The authors conclude that proactive metabolite monitoring is probably not warranted during pregnancy.

Synthesis written by Geno'X. For the full original abstract, please refer to the source publication.

This study provides a reassuring answer to a common practical question: the physiological decline in 6-TGN during pregnancy does not mandate dose adjustment. It is a useful de-escalation message, avoiding unnecessary therapeutic changes in a population where stability is paramount. The retrospective design and moderate sample size nonetheless call for caution before generalization.