Hydroxychloroquine Monitoring Requirements
Yes, patients taking Plaquenil (hydroxychloroquine) require both ophthalmologic and laboratory monitoring, with the primary focus on screening for irreversible retinal toxicity through baseline and annual eye examinations. 1
Ophthalmologic Monitoring (Most Critical)
Baseline Examination
- Perform a comprehensive fundus examination within the first year of starting hydroxychloroquine to rule out preexisting maculopathy, which would be a contraindication to use 1, 2
- Include best corrected distance visual acuity (BCVA), automated threshold visual field testing of the central 10 degrees, and spectral-domain optical coherence tomography (SD-OCT) 1, 2
Annual Screening Schedule
- Begin annual screening after 5 years of use for patients on acceptable doses (≤5.0 mg/kg actual body weight) without major risk factors 1, 3
- Start annual screening earlier than 5 years if major risk factors are present 1
- For pediatric patients, perform yearly screening from the start rather than waiting 5 years 3
Screening Tests Required
The primary screening battery includes:
- Automated visual fields (10-2 pattern) 1
- Spectral-domain optical coherence tomography (SD-OCT) 1
- Multifocal electroretinogram (mfERG) can provide objective corroboration for visual field findings 1
- Fundus autofluorescence (FAF) can show damage topographically 1
Important caveat: For patients of Asian descent, visual field testing should be performed in the central 24 degrees instead of the central 10 degrees, as they may show early damage in a more peripheral pattern 1, 2
Major Risk Factors for Retinal Toxicity
These factors warrant earlier and more frequent screening:
- Daily dose >5.0 mg/kg of actual body weight (not ideal body weight) 1, 3
- Duration of use >5 years 1, 3
- Concomitant renal disease (subnormal glomerular filtration rate) 1
- Concurrent tamoxifen use 1, 2
- Preexisting macular disease 1, 2
The risk of toxicity is <1% in the first 5 years, <2% up to 10 years, but rises to almost 20% after 20 years of use 1, 3
Laboratory Monitoring
Routine Blood Work
- Complete blood count (CBC) and liver function tests (LFTs) annually 3
- The FDA label emphasizes monitoring for cardiac function as clinically indicated, though specific intervals are not mandated 2
Special Circumstances
- Measure liver tests promptly if patients report symptoms suggesting liver injury (fatigue, rash, nausea, dark urine, jaundice), particularly in patients with porphyria cutanea tarda 2
- Correct electrolyte imbalances (hypokalemia, hypomagnesemia) prior to use and monitor during therapy due to QT prolongation risk 2
Cardiac Monitoring Considerations
While not requiring routine ECG screening in asymptomatic patients, be aware that:
- Hydroxychloroquine can cause cardiomyopathy and prolong the QT interval 2
- Monitor cardiac function as clinically indicated, especially in patients with cardiac disease, bradycardia, or those taking other QT-prolonging medications 2
- Discontinue if cardiotoxicity is suspected 2
Critical Clinical Pearls
Retinopathy is irreversible and has no treatment - early detection before RPE damage is essential to preserve central vision 1, 3. However, even when detected early and the drug is stopped, some progression may continue 2.
Dosing is critical: The maximum recommended dose is 5.0 mg/kg of actual body weight, not ideal body weight, as this correlates better with risk 1. For short-statured individuals, dose adjustment is particularly important to avoid overdosage 4.
Do not stop medication for questionable findings: Repeat or validate with additional procedures to avoid unnecessary cessation of valuable medication 1, 3. The goal is to detect definitive toxicity early, not to stop the drug at the first borderline abnormality 1.
Patient counseling is mandatory: Inform patients and prescribing physicians about toxicity risk, proper dosing, and the importance of regular screening 1, 3.