Cure8 research brief
Thiopurines are commonly used in IBD (azathioprine, 6-mercaptopurine). This review links these drugs — especially 6-thioguanine — to liver microvascular injury that can lead to portal hypertension, which may present subtly (low platelets, enlarged spleen).
Recognizing these signs could lead to earlier evaluation and stopping the drug to prevent complications.
IBD patients currently taking or previously exposed to thiopurines (AZA/6-MP/6-TG), parents and clinicians caring for pediatric patients, hepatologists monitoring liver complications, and prescribing gastroenterologists.
This systematic review found that thiopurine drugs (specifically 6-thioguanine, and to a lesser extent azathioprine and 6-mercaptopurine) are associated with a spectrum of hepatic microvascular injury ranging from acute sinusoidal obstruction syndrome (SOS) to a chronic porto‑sinusoidal vascular disorder (PSVD).
New unexplained thrombocytopenia or splenomegaly in a patient on thiopurines were highlighted as early clues that should prompt evaluation for portal hypertension.
The strongest and most consistent evidence came from paediatric acute lymphoblastic leukaemia trials, where 6-thioguanine showed higher rates of hepatic vascular injury compared with 6-mercaptopurine, leading to changes in protocols.
Outside haematology (including IBD), evidence is mainly from observational cohorts and case reports; the review notes dose/exposure and host susceptibility likely influence risk but direct evidence that SOS progresses into PSVD is limited.
The authors recommend stopping thiopurines when PSVD or SOS is suspected and evaluating for portal-hypertension complications (varices, ascites, portal vein thrombosis) if clinical clues appear. This article is an abstracted systematic review (Annals of Hepatology) and summarizes findings across many study types.
This entry is based on the article abstract (systematic review) from Annals of Hepatology. The strongest causal evidence is from paediatric leukaemia trials involving 6-TG; evidence for AZA/6-MP in non‑haematology settings is less consistent and largely observational. The abstract-level summary does not provide detailed incidence rates or individual study quality assessments.
Review the original publication for the complete reporting, methods, and context.
Conflict statement: Declaration of interests None.
This Cure8 brief is based on source text from the linked article. Cure8 is informational only and is not a substitute for professional medical advice, diagnosis, or treatment.
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