Kidney Involvement and Associated Risk Factors in Children with Duchenne Muscular Dystrophy

Kidney dysfunction is a common complication in adults with Duchenne muscular dystrophy (DMD); however, little attention has been paid to kidney function in pediatric patients. Medical records of patients with DMD who were followed up for ≥ 12 months were retrospectively reviewed. Inclusion criteria were (i) aged 5–18 years, (ii) proven mutations in the dystrophin gene, and (iii) absence of structural anomalies of the kidney and urinary tract. Serum creatine kinase (CK) was used as an indirect marker of muscle destruction. Forty-four patients (mean age, 10.9 ± 3.3 years) were included. Blood pressure was evaluated by 24-h ambulatory blood pressure monitoring in 28 patients. Hypertension was found in 9 (32.1%), eight of whom were using steroids. Mild proteinuria, hypercalciuria, hypocalciuria, and hyperphosphaturia in 24-h urine collection (n = 36) were detected in 3 (8.3%), 5 (13.9%), 7 (19.7%), and 6 (16.7%) patients, respectively. Twenty-one (58.3%) demonstrated hyperuricosuria, associated with hyperuricemia in 4. Logarithmic cystatin C (CysC) had a positive correlation to creatinine (Cr) (p = 0.001, r = 0.54), CK (p = 0.048, r = 0.30), and parathormone (PTH) (p = 0.001, r = 0.49). Moreover, the patients were divided into two groups according to median CysC value: group 1 (n = 20, CysC ≤ 0.76 mg/l) and group 2 (n = 24, CysC > 0.76 mg/l). Mean CK, PTH, and Cr levels were significantly elevated in group 2 compared with group 1 (p = 0.010, 0.033, and 0.023, respectively). Long-term exposure to the excessive burden of intracellular components released from damaged muscles may be associated with an increased risk over time of chronic kidney impairment in pediatric DMD patients.