Impaired Kidney Function Associated With High Hydroxychloroquine Levels

Impaired kidney function affects blood concentrations of hydroxychloroquine (HCQ) among patients with systemic lupus erythematosus (SLE), according to study findings published in Clinical Rheumatology.

The study was designed to evaluate factors that affect blood concentrations of HCQ.

Patients with SLE who received 400 mg/day HCQ for 12 or more months at the Peking University People’s Hospital in China were assessed for blood HCQ concentrations.

High HCQ concentrations were defined as greater than the population median.

The study population (N=111) included 93.7% women, 75.7% were younger than 60 years, and had a median SLE duration of 48.0 (IQR, 24.0-87.0) months. A total of 67.6% of patients received prednisone; 79.1% received immunosuppressants; and 74.8% received a weight-adjusted HCQ dose of more than 5 mg/kg.

Stratified by low (n=55) and high (n=56) blood concentrations, a greater percentage of patients with a high vs low concentration received a weight-adjusted dose of more than 5 mg/kg (100% vs 49.1%; P <.001) and a lower body mass index (BMI; median, 21.2 vs 23.2; P =.036).

The only laboratory variable that differed significantly between the low and high concentration groups was estimated glomerular filtration rate (eGFR), which was significantly lower among those with a high vs low blood concentration (mean, 99.22 vs 106.21 mL/min/1.73 m²; P =.011).

Blood HCQ concentrations had a negative linear relationship with eGFR (P =.036).

In the multivariate logistic regression analyses, HCQ concentration was predicted by eGFR (adjusted odds ratio [aOR], 0.97; 95% CI, 0.95-0.99; P =.005) and linked to chronic kidney disease (CKD) stage (aOR, 0.2; 95% CI, 0.04-0.35; P =.013).

The study may have been limited by the small sample size of patients with advanced CKD (stage 3: n=5; stage 4: n=1).

The study authors concluded, “[W]e provide novel evidence that a higher HCQ blood concentrations are associated with low eGFR. This finding reinforces the importance of routine HCQ measurement to maintain normal blood concentrations. HCQ blood monitoring will be useful for dose modification in patients with renal dysfunction.”