Related Experiment Video
Updated: Feb 17, 2026

Analyses of Proteinuria, Renal Infiltration of Leukocytes, and Renal Deposition of Proteins in Lupus-prone MRL/lpr Mice
Published on: June 8, 2022
Hydroxycloroquine blood concentration in lupus nephritis: a determinant of disease outcome?
Cátia Cunha1, Suceena Alexander2, Damien Ashby3
1Nephrology Department, Centro Hospitalar de VilaNova de Gaia/Espinho, Vila Nova de Gaia, Portugal.
Background:
Hydroxychloroquine (HCQ) is a recommended drug in systemic lupus erythematosus (SLE). It has a long terminal half-life, making it an attractive target for therapeutic drug monitoring. The aim of this study was to establish a relationship between blood HCQ concentration and lupus nephritis activity.
Methods:
We conducted a retrospective observational study with data collected from clinical and laboratory records. Inclusion criteria were patients followed in the lupus clinic with biopsy-proven International Society of Nephrology/Renal Pathology Society Classes III, IV or V lupus nephritis on HCQ for at least 3 months (200-400 mg daily) and with HCQ levels measured during treatment. Exclusion criteria were patients on renal replacement therapy at baseline or patients lost to follow-up.
Results:
In 171 patients, the HCQ level was measured in 1282 samples. The mean HCQ blood level was 0.75±0.54mg/L and it was bimodally distributed. An HCQ level <0.20 mg/L [232 samples (18.1%)] appeared to define a distinct group of abnormally low HCQ levels. For patients in complete or partial remission at baseline compared with those remaining in remission, patients with renal flare during follow-up had a significantly lower average HCQ level (0.59 versus 0.81 mg/L; P= 0.005). Our data suggest an HCQ target level to reduce the likelihood of renal flares >0.6 mg/L (600 ng/mL) in those patients with lupus nephritis.
Conclusion:
HCQ level monitoring may offer a new approach to identify non-adherent patients and support them appropriately. We propose an HCQ minimum target level of at least 0.6 mg/L to reduce the renal flare rate, but this will require a prospective study for validation.
Related Concept Videos
Factors Affecting Renal Clearance: Drug's Physicochemical Properties and Plasma Levels
One important factor is the drug's molecular size. The kidneys readily excrete smaller molecules below 300 Daltons (Da). On the other hand, molecules weighing between 300 and 500 Da are excreted through both urine and bile. Larger molecules above 500 Da tend to be excreted...
Factors Affecting Renal Clearance: Renal Impairment
One condition associated with renal failure is uremia. Uremia is characterized by impaired glomerular filtration and fluid accumulation in the body. This condition hinders the renal clearance of drugs, resulting in drug accumulation and potential...
Drug Dosing in Renal Diseases: Dose Adjustments Based on Drug Clearance and Elimination Rate Constant
Effect of Hepatic Disease on Pharmacokinetics: Drug Dosing and Hepatic Blood Flow
Factors Affecting Renal Clearance: Drug Distribution and Drug Interactions
One important factor is the relationship between renal clearance and the apparent volume of distribution. Renal clearance tends to be inversely proportional to the apparent volume of distribution. Drugs with an extensive distribution volume or those...
Drug Dosing in Renal Diseases: Measurement of Serum Creatinine Concentration and Clearance

