A case of Duchenne muscular dystrophy recovered from prolonged ischemic kidney injury which emerged with a normal creatinine level

Abstract

Duchenne muscular dystrophy (DMD) is an inherited disease characterized by progressive degeneration of the skeletal muscles. Renal dysfunction in patients with DMD has recently become more apparent as life expectancy has increased owing to advances in respiratory devices and heart failure therapies. A 23-year-old man with DMD who required nasal tube feeding was referred to our hospital with a 4-month history of renal dysfunction and anemia. The patient's serum creatinine (sCr) level was within the normal range (0.84 mg/dL), but his serum cystatin C level and estimated glomerular filtration rate calculated by cystatin C (5.90 mg/L and 7.5 mL/min/1.73 m², respectively) indicated severe renal impairment. A urinalysis revealed elevated levels of protein and tubular markers. The patient's hemoglobin and erythropoietin levels indicated renal anemia. Hypotension, a collapsed inferior vena cava, and a poor tube feeding episode suggested that the kidney injury was due to renal ischemia, which progressed to tubulointerstitial kidney injury, an intrinsic kidney injury. The angiotensin-converting enzyme inhibitors and beta-blockers were discontinued, and extracellular fluid was infused. Thereafter, the patient's renal function recovered. Subsequently, the patient's urinary findings and anemia improved. Although advances in cardioprotective agents are expected to improve the prognosis of patients with DMD, it is important to consider that the number of patients with kidney injury due to renal ischemia may increase and that it is difficult to evaluate renal function using sCr level in patients with DMD because of decreased skeletal muscle mass.

Keywords: Cystatin C; Dehydration; Duchenne muscular dystrophy; Kidney injury.

Fig. 1

Clinical course of kidney function parameters and anemia before the first visit. BUN, blood urea nitrogen; Hb, hemoglobin; sCr, serum creatinine

Fig. 2

Computed tomography scan of the abdomen. a The kidney is approximately 9 cm long (lower limit of normal); b Highly atrophied skeletal muscles

Fig. 3

Echocardiogram of the patient at the first visit. Left ventricular ejection fraction: 50–55%. Left ventricular end-diastolic diameter: 36.4 mm. Left ventricular end-systolic diameter: 26.0 mm. E/A ratio: 1.1. E/e’ ratio: 4.9. Inferior vena cava diameter: maximum, 6.9 mm; minimum, 3.4 mm. Right heart overload (−). Wall motion abnormality (−). Valvular disease (−)

Fig. 4

Patient’s clinical course. 24 h CCr, 24-h measured creatinine clearance; β2-MG, β2-microglobulin; BP, blood pressure; eGFRcys, estimated glomerular filtration rate calculated by cystatin C; Hb hemoglobin, NAG N-acetyl glucosaminidase, sCr serum creatine