[Renal dysfunction is a frequent complication in patients with advanced stage of Duchenne muscular dystrophy]

Mechanical ventilation and cardioprotective therapy have significantly improved the prognosis and quality of life of patients with Duchenne muscular dystrophy (DMD). The incidence of congestive heart failure is on declining trend by meticulous care. Meanwhile, elongation of decreased cardiac function can provoke instability in circulation. Recently, we experienced six DMD patients who died from acute renal failure with preserved cardiac function (brain natriuretic peptide: BNP <100 pg/ml, fractional shortening: FS >15% and left ventricular diameter: LVD <50mm). In some patients, hypovolemia induced by low water intake, diarrhea or dose-up of diuretics was thought to be a trigger of renal failure. Since the value of creatinine (Crnn) decreased in amyotrophic patients, we evaluated renal function in 103 patients with DMD using cystatin C (CysC), which is a sensitive renal marker and unaffected by muscle volume. In addition, we assessed β2-microglobulin (b2MG) in 24 patients, because it is also unaffected by muscle volume. The correlation between logarithm of CysC (LogCysC) and logarithm of b2MG was quite high (r=0.954), though that between LogCysC and logarithm of Crnn was not adequate (r=0.623). The average of CysC increased along with age, and more than 30% of patients over 30 years old showed abnormal values. Hemoglobin and logCysC was also negatively associated (r=-0.519), and patients with hemoglobin less than 10 g/dl showed elevated values of CysC. Cardiac indices such as FS (r=-0.250) and logarithm of BNP (r=0.319) showed weak correlations with logCysC, though significant correlation was not detected between LVD and LogCysC. Since renal dysfunction is a common complication in advanced stage of DMD patients, proper managements of water balance and anemia is important. In the medical managements for DMD, we should pay attention to cardiac-renal-anemia association.