What tests should be done before starting Mycophenolate Mofetil (MMF)?

Pre-Treatment Testing Requirements for Mycophenolate Mofetil (MMF)

Before starting mycophenolate mofetil (MMF), patients should undergo complete blood count with differential, comprehensive metabolic panel, pregnancy testing for females of reproductive potential, and a full body skin examination.

Essential Laboratory Tests

• Complete blood count (CBC) with differential at baseline to assess for pre-existing cytopenias, as MMF can cause bone marrow suppression 1
• Comprehensive metabolic panel (CMP) including liver function tests and renal function at baseline, as MMF can cause hepatotoxicity and requires dose adjustment in renal impairment 1
• Pregnancy test with sensitivity of at least 25 mIU/mL for all females of reproductive potential immediately before starting MMF, with a follow-up test 8-10 days later 2
• Hepatitis B, hepatitis C, and tuberculosis screening should be performed if the patient will be receiving MMF along with JAK inhibitors or other highly immunosuppressive regimens 1

Clinical Assessments

• Full body skin examination, preferably by a dermatologist, to establish a baseline before initiating therapy 1
• Blood pressure measurement to establish baseline, as hypertension can be a side effect 3
• Assessment for active serious digestive system disease, as MMF should be administered with caution in patients with active peptic ulcer disease 2

Special Considerations

Pregnancy Prevention

• For females of reproductive potential, contraceptive counseling must be provided before starting MMF 2
• Acceptable contraception must be used during MMF therapy and for 6 weeks after stopping treatment 2
• MMF carries an FDA black box warning for use during pregnancy due to teratogenic effects 3

Medication Interactions

• Review of current medications to identify potential drug interactions, particularly with:
  • Activated charcoal, aluminum/magnesium salts, cholestyramine, and iron (which inhibit absorption) 3
  • Azathioprine (which may increase purine metabolism inhibition) 3
  • Hormonal contraceptives (MMF may reduce effectiveness) 3, 2

Monitoring Schedule After Initiation

• CBC should be monitored:

  • 2-3 weeks after starting and 2-3 weeks after any dose increase 1
  • Every 3 months once on a stable dose 1
  • Weekly for the first month, twice monthly for months 2-3, and monthly for the remainder of the first year in high-risk patients 3

• Liver function tests should be monitored:

  • 2-3 weeks after starting and 2-3 weeks after any dose increase 1
  • Every 3 months once on a stable dose 1

Common Pitfalls to Avoid

• Failure to perform pregnancy testing before initiating MMF in females of reproductive potential can lead to fetal exposure to a teratogenic medication 2
• Overlooking baseline cytopenias that may worsen with MMF therapy 3
• Not establishing a baseline skin examination, which is important for monitoring potential dermatologic side effects and skin malignancies 1
• Neglecting to counsel patients about avoiding live vaccines during treatment 3
• Failure to monitor for gastrointestinal side effects, which are common with MMF and may require dose adjustment or alternative formulations 4, 5

By following these pre-treatment testing guidelines, clinicians can minimize risks and optimize the safety profile of MMF therapy for their patients.