ArticleArthritis research & therapy2020
Hydroxychloroquine levels in patients with systemic lupus erythematosus: whole blood is preferable but serum levels also detect non-adherence.
Article in Arthritis research & therapy, 2020. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 18 papers, 1 of them a synthesis that pooled it.
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Who cites it
18 citing papers in PubMed, 1 synthesis or guideline pooled it, 27 citations in OpenAlex.
- II Brazilian Society of Rheumatology consensus for lupus nephritis diagnosis and treatment.Advances in rheumatology (London, England) · 2024Guideline
- Hydroxychloroquine levels in pregnancy and materno-fetal outcomes in systemic lupus erythematosus patients.Rheumatology (Oxford, England) · 2025Trial
- Increasing the utilisation of hydroxychloroquine blood level testing in lupus: a quality improvement project.Lupus science & medicine · 2026Article
- Defining Optimally Safe and Effective Blood Levels of Hydroxychloroquine in Lupus: An Important Step Toward Precision Drug Monitoring.Arthritis & rheumatology (Hoboken, N.J.) · 2026Observational
- Real-World Longitudinal Data on the Impact of Hydroxychloroquine Blood Level Monitoring on Lupus Outcomes: Results of a Prospective Longitudinal Cohort Study.Arthritis care & research · 2026Article
- A Case Series and Review of Hydroxychloroquine Toxicity and Monitoring: How Do We Dose Hydroxychloroquine?Cureus · 2025Article
- Refining lupus management: a comprehensive review of HCQ blood levels.Rheumatology advances in practice · 2025Review
- Interpreting hydroxychloroquine blood levels for medication non-adherence: a pharmacokinetic study.Lupus science & medicine · 2024Article
- Therapeutic Drug Monitoring in Patients with Systemic Lupus Erythematosus: Utility and Gaps.Journal of clinical medicine · 2024Review
- Evaluation of early retinal changes in patients on long-term hydroxychloroquine using optical coherence tomography angiography.Therapeutic advances in drug safety · 2024Article
- Association Between Severe Nonadherence to Hydroxychloroquine and Systemic Lupus Erythematosus Flares, Damage, and Mortality in 660 Patients From the SLICC Inception Cohort.Arthritis & rheumatology (Hoboken, N.J.) · 2023Article
- Analytical and Clinical Validation of Assays for Volumetric Absorptive Microsampling (VAMS) of Drugs in Different Blood Matrices: A Literature Review.Molecules (Basel, Switzerland) · 2023Review
- Therapeutic drug monitoring of disease-modifying antirheumatic drugs in circulating leukocytes in immune-mediated inflammatory diseases.Inflammopharmacology · 2023Review
- Worse long-term renal outcome of lupus nephritis patients of African descent living in Europe.RMD open · 2022Article
- Drug monitoring in systemic lupus erythematosus.Current opinion in pharmacology · 2022Review
- Hydroxychloroquine PK and exposure-response in pregnancies with lupus: the importance of adherence for neonatal outcomes.Lupus science & medicine · 2022Article
- Effects of hydroxychloroquine and its metabolites in patients with connective tissue diseases.Inflammopharmacology · 2021Article
- Hydroxychloroquine as a Chemoprophylactic Agent for COVID-19: A Clinico-Pharmacological Review.Frontiers in pharmacology · 2020Review
Corrections and comments
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Authors and funding
35 authors at 19 institutions in 3 countries.
Funding
No grant is acknowledged in the PubMed record.
Abstract
backgroundHydroxychloroquine (HCQ) levels can be measured in both serum and whole blood. No cut-off point for non-adherence has been established in serum nor have these methods ever been compared. The aims of this study were to compare these two approaches and determine if serum HCQ cut-off points can be established to identify non-adherent patients.
methodsHCQ levels were measured in serum and whole blood from 573 patients with systemic lupus erythematosus (SLE). The risk factors for active SLE (SLEDAI score > 4) were identified by multiple logistic regression. Serum HCQ levels were measured in 68 additional patients known to be non-adherent, i.e. with whole-blood HCQ < 200 ng/mL.
resultsThe mean (± SD) HCQ levels were 469 ± 223 ng/mL in serum and 916 ± 449 ng/mL in whole blood. The mean ratio of serum/whole-blood HCQ levels was 0.53 ± 0.15. In the multivariate analysis, low whole-blood HCQ levels (P = 0.023), but not serum HCQ levels, were independently associated with active SLE. From the mean serum/whole-blood level ratio, a serum HCQ level of 106 ng/mL was extrapolated as the corresponding cut-off to identify non-adherent patients with a sensitivity of 0.87 (95% CI 0.76-0.94) and specificity of 0.89 (95% CI 0.72-0.98). All serum HCQ levels of patients with whole-blood HCQ below the detectable level (< 20 ng/mL) were also undetectable (< 20 ng/mL).
conclusionsThese data suggest that whole blood is better than serum for assessing the pharmacokinetic/pharmacodynamic relation of HCQ. Our results support the use of serum HCQ levels to assess non-adherence when whole blood is unavailable.
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