Laboratory Monitoring for Hydroxychloroquine
For patients on hydroxychloroquine, obtain CBC and liver function tests annually, with baseline and yearly retinal screening starting immediately after treatment initiation. 1
Baseline Laboratory Testing
Before starting hydroxychloroquine, obtain the following baseline tests:
- Complete blood count (CBC) with differential 1
- Liver function tests (LFTs) including ALT and AST 1
- G6PD screening to rule out deficiency, which increases hemolysis risk 2
Ongoing Laboratory Monitoring Schedule
Hematologic and Hepatic Monitoring
- CBC and LFTs annually during prolonged therapy 1
- More frequent monitoring is warranted if additional risk factors are present 2
Ophthalmologic Monitoring
- Baseline retinal screening should be completed as soon as possible after starting treatment 1
- Annual retinal screening thereafter, using automated visual fields (if age-appropriate) plus spectral-domain optical coherence tomography 1
- Treatment does not need to be delayed for initial retinal screening 1
- Screening can be combined with uveitis screening when feasible 1
Key Differences from Adult Monitoring
Pediatric patients require more frequent retinal screening than adults. 1
- Children should have yearly screening rather than waiting 5 years between baseline and subsequent screening as recommended for adults 1
- This is due to concerns about cumulative and developmental effects of hydroxychloroquine, as children may be on treatment for prolonged periods and may not articulate vision concerns 1
Critical Monitoring Pitfalls to Avoid
Do not delay annual retinal examinations in pediatric patients. The cumulative toxicity risk in children differs from adults due to longer potential treatment duration and developmental considerations. 1
Screen for G6PD deficiency before initiating therapy to prevent hemolytic complications. 2
Increase monitoring frequency if the patient develops cytopenias or elevated liver enzymes, as rare but serious hematologic complications including pancytopenia have been reported. 2
When to Consider Dose Adjustment or Discontinuation
While the guidelines do not specify exact thresholds for hydroxychloroquine dose modification based on laboratory values, clinically significant abnormalities in CBC or LFTs should prompt reassessment of therapy. 1
Retinal toxicity findings on ophthalmologic examination warrant immediate consultation with ophthalmology and consideration of treatment discontinuation. 1