Before starting

Required

• Baseline
  • Estimated glomerular filtration rate · avoid if less than 30 mL/minute/1.73 m²; half dose if less than 60mL/minute/1.73m²
  • Full blood count · contraindicated if platelet count less than 100 x 10⁹/L
  • Liver function tests · avoid in severe impairment; caution in mild to moderate
  • Uric acid

Sickle cell disease

• Baseline
  • Estimated glomerular filtration rate · avoid if less than 30 mL/minute/1.73 m²; half dose if less than 60mL/minute/1.73m²
  • Full blood count
  • Liver function tests · avoid in severe impairment; caution in mild to moderate
  • Lactate dehydrogenase (LDH)
  • Reticulocyte count
  • Urate
  • Urea and electrolytes
  • Uric acid

Consider in patients at risk of infection

• Baseline
  • Hepatitis B
  • Hepatitis C

After started or dose changed

Sickle cell disease

• Weekly for first 4 weeks; then if stable, fortnightly for 8 weeks
  • Full blood count

Other indications

• Weekly
  • Full blood count · until stable on the effective dose.

Ongoing once stable

Sickle cell disease

• Every 2-3 months; every 2 weeks if on maximum dose
  • Full blood count
• Every 2 - 3 months
  • Lactate dehydrogenase (LDH)
  • Liver function tests · avoid in severe impairment; caution in mild to moderate
  • Urate
  • Urea and electrolytes

Other indications

• Every 1 - 3 months
  • Full blood count
  • Estimated glomerular filtration rate
  • Liver function tests · avoid in severe impairment; caution in mild to moderate
  • Uric acid

Abnormal results

Monitor trends

Be aware of trends in results and respond accordingly.

Respond to absolute levels

Consider stopping treatment, contacting a specialist, and ensuring levels recover before re-starting if any of the following develop:

Full blood count

• WCC less than 2.5 x 10⁹/L
• Neutrophils less than 1.0 x 10⁹/L
• Platelets less than 80 x 10⁹/L
• Reticulocytes less than 80 x 10⁹/L and haemoglobin less than 90g/L
• Haemoglobin below 45g/L or dropped by over 30g/L from baseline

Notes

Advice to patients

Advise patients to:

• maintain a high fluid intake during treatment
• protect skin from sun exposure if on long-term therapy

Secondary malignancies

Patients receiving long-term therapy for malignant disease should be monitored for secondary malignancies.

Bibliography

• Neon Healthcare Ltd . Summary of Product Characteristics – Hydrea 500 mg Hard Capsules. Last revised 02/2023 [cited 08/08/2020]
• British Association Dermatologists. Patient information leaflet for hydroxycarbamide. Published October 2017 [cited 30/07/2020]
• Addmedica. Summary of Product Characteristics – Siklos 1000 mg film-coated tablets. Last revised 07/2019 [cited 30/07/2020]
• National Institute for Health and Care Excellence (NICE). Hepatitis B and C testing: people at risk of infection [PH43]. Dec 2012 [updated Mar 2013; cited June 2020]
• Scottish Paediatric & Adult Haemoglobinopathy Network. Use of Hydroxycarbamide in adults with Sickle Cell Disease. 2020 [cited 30/07/2020]
• Joint Formulary Committee. British National Formulary (online) London: BMJ Group and Pharmaceutical Press [cited 30/07/2020]
• British Medical Journal (BMJ). BMJ Best Practice. Polycythaemia vera. Last updated 31/05/2018 [cited August 2020]

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