From the Guidelines
Laboratory Monitoring for Hydroxychloroquine Therapy
Laboratory monitoring for Plaquenil (hydroxychloroquine) typically includes regular ophthalmologic examinations to assess for retinal toxicity, which can occur with long-term use or high doses 1. Patients should undergo a baseline examination within the first year of treatment and annually thereafter, with particular attention to visual acuity, retinal function, and optical coherence tomography (OCT) imaging 1.
Key Monitoring Recommendations
- Baseline screening: Fundus examination within the first year of use, with additional tests like visual fields and SD OCT if maculopathy is present 1.
- Annual screening: Begin after 5 years of use in low-risk patients, but sooner in the presence of major risk factors such as high doses, concomitant tamoxifen use, or impaired renal function 1.
- Complete blood counts (CBC) and liver function tests (LFTs): Perform periodically, particularly in patients with pre-existing hematologic or hepatic conditions, to monitor for potential adverse effects 1.
Important Considerations
- The risk of retinal toxicity is low at doses ≤5 mg/kg/day actual body weight, but increases with duration of treatment and in the presence of risk factors like chronic kidney disease and pre-existing retinal or macular disease 1.
- Effective communication among prescribing physicians, patients, and eye care providers is crucial to optimize the utility and safety of hydroxychloroquine therapy 1.
From the FDA Drug Label
Monitor blood cell counts periodically in patients on prolonged hydroxychloroquine sulfate therapy. Measure liver tests promptly in patients who report symptoms that may indicate liver injury, such as fatigue, rash, nausea, dark urine, or jaundice. Assess muscle strength and deep tendon reflexes periodically in patients on long-term therapy with hydroxychloroquine sulfate. Measure blood glucose in patients presenting with clinical symptoms suggestive of hypoglycemia
The required laboratory monitoring for hydroxychloroquine (Plaquenil) therapy includes:
- Periodic blood cell counts to monitor for myelosuppression
- Liver tests to monitor for hepatotoxicity
- Muscle strength and deep tendon reflexes to monitor for skeletal muscle myopathy or neuropathy
- Blood glucose to monitor for hypoglycemia 2
From the Research
Laboratory Monitoring for Hydroxychloroquine Therapy
- A baseline ophthalmologic examination is recommended for all patients starting long-term hydroxychloroquine therapy, including automated visual fields and spectral-domain optical coherence tomography (SD-OCT) for patients with pre-existing macular conditions 3, 4, 5, 6
- Annual screening can be deferred for the first 5 years of hydroxychloroquine treatment unless the patient has a major risk factor, such as high daily dosage or cumulative dose 3, 4, 6
- Objective tests, such as multifocal electroretinogram (mfERG), SD-OCT, and fundus autofluorescence (FAF), can be used for routine screening, in addition to 10-2 automated fields 7, 6
- Patients should be aware of the risk of toxicity and the rationale for screening, which is to detect early changes and minimize visual loss, not necessarily to prevent it 6
- The American Academy of Ophthalmology recommends that patients be screened annually after 5 years of hydroxychloroquine use, or sooner if there are unusual risk factors, and that the drug be stopped if possible when toxicity is recognized or strongly suspected 6
Risk Factors for Hydroxychloroquine Toxicity
- High daily dosage or cumulative dose 4, 7, 6
- Pre-existing macular conditions 3, 5
- Short stature, which may require dose adjustment based on ideal body weight 6
- Concurrent use of other medications, such as nonsteroidal antiinflammatory drugs 4