MUSCLE CRAMPS: I

A 52‐year‐old white male presented for evaluation of moderate azotemia (blood urea nitrogen [BUN] 52 mg/dl and creatinine 5.4 mg/dl). Renal history was positive for hypertension (156/100), nocturia, and polyuria. There was a 10‐year history of an idiopathic seizure disorder. Medications were phenytoin 100 po tid and diltiazem 240 mg sustained release bid. An S4 and 1 + peripheral edema were the only positive physical findings. Postural blood pressure changes were absent . Laboratory findings included a urinalysis with 2+ protein, finely granular casts, and 5–10 WBCs/ HPF. Twenty‐four hour urine protein was 1.1 g/24 h. Renal ultrasound: 9.2 cm left, 8.9 cm right kidney, and left renal biopsy demonstrated chronic interstitial nephritis. Other potential causes for interstitial injury were ruled out and phenytoin was discontinued. Prevention of seizures was obtained with phenobarbital . A few months later, the patient complained of excruciating nocturnal cramps in both gastrocnemius, occurring four to five times per night and necessitating hot baths and passive stretching of the calf muscles for temporary relief. Muscle exam was normal; neurologic exam revealed symmetric sensory and motor neuropathy consistent with renal failure. Thyroid function, magnesium, sodium, and calcium concentrations were normal. The patient was treated with vitamin E 400 IU/day with a decreased frequency and severity of cramps. Azotemia progressed to dialysis dependence (continuous ambulatory peritoneal dialysis [CAPD]). His cramp frequency and intensity on CAPD has waxed and waned. His dry weight has been frequently reassessed and increased as necessary. He has continued vitamin E with periodic use of verapamil or quinine, in addition, for cramp relief .