Azathioprine/Mercaptopurine
This is not an exact science.
Weekly FBC/LFTs from induction or dose change for 4-6 weeks then every 4-6 weeks thereafter (until advised otherwise).
Azathioprine/Mercaptopurine Monitoring Advice
These guidelines apply to mainly for patients with Inflammatory Bowel Disease (IBD). Patients may be on these drugs for other indications - please note that patients with autoimmune liver disease / cirrhosis may well have abnormal indices at baseline – please refer to these when considering abnormal monitoring results and if in doubt contact GI directly.
Frequency of blood monitoring
Abnormal indices
Azathioprine/Mercaptopurine
WBC 3.0-3.5 x 109/l - This can occur with transient viral infections. Recheck in 1 week. If WBC decreasing discuss with GI
WBC 2.5-3.0 x 109/l - Discuss with GI re dose reduction
WBC <2.5 - Withhold drug and discuss with GI
Neutrophils 1.5-2.0 x 109/l - Recheck in 1 week if still abnormal discuss with GI
Neutrophils <1.5 x 109/l - Withhold drug and discuss with GI
MCV >105 fl This may simply represent Thiopurine drug effect but in all cases check B12 and folate and treat appropriately
AST, ALT > 2 fold rise (from the upper limit of the reference range) - Recheck and discuss with GI
Severe sore throat, abnormal bruising or sepsis - Immediate FBC and withhold until the result of FBC is available. Discuss with GI/Acute Medical Team if concerns.
WBC 3.0-3.5 x 109/l - This can occur with transient viral infections. Recheck in 1 week. If WBC decreasing discuss with GI
WBC 2.5-3.0 x 109/l - Discuss with GI re dose reduction
WBC <2.5 - Withhold drug and discuss with GI
Neutrophils 1.5-2.0 x 109/l - Recheck in 1 week if still abnormal discuss with GI
Neutrophils <1.5 x 109/l - Withhold drug and discuss with GI
MCV >105 fl This may simply represent Thiopurine drug effect but in all cases check B12 and folate and treat appropriately
AST, ALT > 2 fold rise (from the upper limit of the reference range) - Recheck and discuss with GI
Severe sore throat, abnormal bruising or sepsis - Immediate FBC and withhold until the result of FBC is available. Discuss with GI/Acute Medical Team if concerns.
