Renal Dysfunction is Common in Myotonic Dystrophy

Background: Renal dysfunction is often overlooked in patients with Neuromuscular Disorders (NMD) since creatinine keeps low values due to amyotrophy. Objective: To assess renal function of NMD patients, we made a retrospective study using cystatin C (CysC), which is not influenced by muscle volume. Patients and methods: Subjects were 563 NMD patients including 31 congenital muscular dystrophy (CMD), 155 Duchenne muscular dystrophy (DMD), 114 other dystophinopathies (Dys), 121 myotonic dystrophy (DM), 82 other muscular dystrophies (MD) and 60 motor neuron diseases (NMD). Patients’ profiles, laboratory and ultrasound cardiogram data were collected from medical records and statistical analyses were done. I have obtained institutional review board approval, as necessary. Results: CysC was elevated (>0.9 mg/L) in 0 CMD, 14 DMD, 12 Dys, 28 DM, 6 MD and 15 MND patients, respectively. Logarithm of CysC (lgCysC) was correlated to age and lower in female patients. After adjustment of age and sex, lgCysC was higher in DM compared to CMD, Dys, MD and MND. After adjustment of age in male patients, lgCysC was also higher in DM compared to DMD. In DM, LgCys was correlated to age, CTG repeats number, logarithm of creatine kinase, logarithm of cardiac troponin T (lgTnT) and triglyceride (TG). After adjustment of CTG repeats, age, lgTnT, TG and hemoglobin A1c were associated to lgCysC. Conclusion: Chronic kidney disease should be considered as a complication in DM. Although further studies are needed to elucidate the pathomechanism, DM itself, subclinical cardiac damage and metabolic dysfunction might have influences on renal function.