From the Guidelines
While on Plaquenil (hydroxychloroquine), it is essential to monitor complete blood counts, liver function tests, and kidney function tests periodically, typically every 3-6 months, to detect potential side effects early and allow for dose adjustments or medication changes if needed. According to the 2021 American College of Rheumatology guideline 1, for patients taking hydroxychloroquine, CBC and LFTs are conditionally recommended to be monitored annually. However, more frequent monitoring may be necessary in certain situations, such as pre-existing liver or kidney conditions, elderly patients, or those taking other medications that might interact with Plaquenil. Some key points to consider when monitoring patients on Plaquenil include:
- Complete blood counts to check for anemia, low white blood cells, or platelets
- Liver function tests to ensure the liver is handling the medication properly
- Kidney function tests since the drug is eliminated through the kidneys
- Blood glucose levels, as Plaquenil can affect blood sugar It's also important to note that blood monitoring complements, but doesn't replace, the regular eye exams needed to check for retinal toxicity, which is a serious potential side effect of long-term Plaquenil use, as highlighted in the 2021 joint statement on hydroxychloroquine use with respect to retinal toxicity 1.
From the Research
Blood Work to Monitor While on Plaquenil (Hydroxychloroquine)
When taking Plaquenil (hydroxychloroquine), it is essential to monitor certain blood work to ensure safe and effective treatment. The following are some key laboratory tests to consider:
- Complete Blood Count (CBC) to monitor for signs of hemolysis, thrombocytopenia, or other blood disorders 2, 3
- Comprehensive Metabolic Panel (CMP) to assess liver and kidney function, as well as glucose and electrolyte levels 3
- Glucose-6-phosphate dehydrogenase (G6PD) deficiency screening, especially in patients with a history of G6PD deficiency or those at high risk of developing hemolytic anemia 4
- Hydroxychloroquine blood levels to optimize dosing and minimize the risk of thrombosis in patients with systemic lupus erythematosus (SLE) 5
Laboratory Abnormalities Associated with Hydroxychloroquine
Studies have shown that hydroxychloroquine can cause various laboratory abnormalities, including:
- Hemolysis, particularly in patients with G6PD deficiency 4
- Thrombocytopenia, which can be severe and recurrent 2
- Elevated liver enzymes, such as alanine transferase and alkaline phosphatase 3
- Glomerular filtration rate abnormalities, which can indicate kidney dysfunction 3
- Lymphopenia, which can increase the risk of infections 3
Monitoring Frequency and Adjustments
The frequency of laboratory monitoring and adjustments to hydroxychloroquine dosing should be individualized based on patient factors, such as comorbidities, disease activity, and concomitant medications. Studies suggest that severe laboratory abnormalities are rare, but regular monitoring can help identify potential issues early on 3, 5.