Before starting

Required

• Baseline
  • Full blood count
  • Liver function tests
  • Urea and electrolytes
  • TPMT assay
  • Serum creatinine (for creatinine clearance) or Estimated glomerular filtration rate

Consider

• Baseline
  • Epstein Barr Virus · consider antivirals in acute infection
  • Hepatitis B
  • Hepatitis C
  • HIV
  • NUDT15 genotype
  • Varicella Zoster Virus Immunity · if no history of infection; vaccinate if low

After started or dose changed

Consider

• At week 2, 4, 8 and 12
  • Full blood count
  • Liver function tests
  • Serum creatinine (for creatinine clearance) or Estimated glomerular filtration rate
  • Urea and electrolytes

Ongoing once stable

Consider

• Every 3 months
  • Full blood count
  • Liver function tests
  • Serum creatinine (for creatinine clearance) or Estimated glomerular filtration rate
  • Urea and electrolytes

Abnormal results

Monitor trends

Be aware of trends in results and respond accordingly.

Respond to absolute levels

Consider stopping treatment and contacting a specialist if any of the following develop:

Full blood count

• Albumin less than 30g/L
• Neutrophils less than 2 x 10⁹/L; if less than 1 x 10⁹/L, consider antibiotics and possibly GCSF if febrile
• Platelets less than 140 x 10⁹/L
• WCC less than 3.5 x 10⁹/L
• MCV greater than 105fL

Liver function

• AST or ALT greater than 100units/mL

Clinical conditions

• Pancreatitis develops
• Patient develops skin or mucosal reaction (e.g. rash, pruritus, or throat ulceration), sore throat, fever, unexplained bruising or bleeding, nausea, vomiting diarrhoea or weight loss, diffuse alopecia, breathlessness, infection or cough, or peripheral neuropathy

Renal function

• Creatinine increase greater than 30% above baseline over 12 months
• Calculated GFR less than 60ml/min/1.73m² (repeat in 1 week, if still more than 30% from baseline, withhold and discuss with specialist team)

Notes

Advice to patients

Advise patients to:

• report immediately any signs or symptoms of bone marrow suppression (e.g. inexplicable bruising or bleeding)
• report immediately any signs or symptoms of liver impairment (e.g. new onset jaundice)
• protect skin from sun exposure (given possible increased risk of non-melanoma skin cancer)

Bibliography

• NICE Clinical Knowledge Summaries (CKS). DMARDs: Summary. Updated Jul 2018 [cited 31/07/2020]
• Joint Formulary Committee. British National Formulary (online) London: BMJ Group and Pharmaceutical Press [cited 13/08/2020]
• Lamb CA, Kennedy NA, Raine T et al. British Society of Gastroenterology consensus guidelines on the management of inflammatory bowel disease in adults. Gut 2019; 68:s1-s107 [cited 30/07/2020]
• Personal communication. Specialists at Guys and St Thomas’ NHS Foundation Trust. 11/05/2020
• National Institute for Health and Care Excellence (NICE). Crohn’s disease: management [NG129]. May 2019 [cited 31/07/2020]
• Public Health England. Contraindications and special considerations: the green book, chapter 6. Published 20/03/2013. Last updated 26/10/2017 [cited 10/05/2020]
• Warner B, Johnston E, Arenas-Hernandez M et al. A practical guide to thiopurine prescribing and monitoring in IBD. Frontline Gastroenterology 2016;0:1–6. [cited 30/07/2020]
• Meggitt SJ, Anstey AV, Mohd Mustapa MF et al. British Association of Dermatologists’ guidelines for the safe and effective prescribing of azathioprine 2011. Br J Dermatol 2011; 165; 711-734. Published October 2011 [cited 30/07/2020]

Update history