Advances in the Clinical Use of Hydroxychloroquine Levels

Katherine Chakrabarti; W. Joseph McCune


Curr Opin Rheumatol. 2022;34(3):151-157. 

In This Article


Retinopathy is a feared complication of hydroxychloroquine use and the ability to identify patients at high risk for retinopathy is highly sought after by rheumatologists.

In a sentinel article, Petri et al.[23] in 2020 reported that blood levels of hydroxychloroquine helped predict retinal toxicity and should be used in clinical practice to guide dosing of hydroxychloroquine going forward. The study included 537 patients with SLE, 23 of whom (4.3%) developed retinal toxicity. Retinopathy was more common with higher hydroxychloroquine blood levels and usually occurred in patients treated for a duration greater than 5 years. The authors concluded that hydroxychloroquine levels should guide decreasing the dose of hydroxychloroquine to minimize toxicities.[23]

Interestingly, an article by Lenfant et al.[24] did not find a similar significant relationship between hydroxychloroquine levels and risk for toxicity. The study included 23 patients on hydroxychloroquine with retinal toxicity and 547 healthy controls on hydroxychloroquine for more than 6 months. The study did, however, identify a relationship between cumulative dose of hydroxychloroquine and longer duration of medication use and risk for retinopathy.[25] The author hypothesized that differences in control populations may have contributed to discordant findings between studies.