To the editor:
We present a male, who developed severe habdomyolysis after an infectious episode leading to acute oliguric renal failure that required hemodialysis. He was 18 years old and had a history of febrile episodes in the childhood and tonsillectomy. He referred «dark-colored urine after strenuous efforts» and consumed no toxics.
He was evaluated at the Emergency Room because of generalized muscle pain and odynophagia. Physical examination was unremarkable except for hyperemic pharynx and intense pain on muscle palpation.
Laboratory parameters were: Biochemistry: Urea 49.6 mg/dL, Cr 2.05 mg/dL, Na 132 mEq/L, K 4.9 mEq/L, ionic calcium 4 mEq/L, uric acid 4.5 mg/dL, CK 285.390 U/L; CK-MB 4353 U/L. Arterial blood gas analysis: pH 7.40; pCO2 33 mmHg; HCO3 20 mmol/L ; PO2 98 mmHg , Sat 97.4%. Blood cell counts: Hb: 17.5 g/dL; hematocrit: 47.6% ; MCV: normal, leucocytes: 13.210 (neutrophils: 88%), other parameters were normal. Urine: density 1010; pH: 5.5, leucocytes 25/ul; erythrocytes > 300 and normal sediment. Ions in urine: Na 77; K 25 ; FENa < 1. Toxics in urine: negative.
Renal ultrasound was normal. The scintigraphy showed abnormal distribution of radiotracer with intense deposits in the muscles of the thorax, abdomen and extremities (fig. 1). A diagnosis of acute renal failure due to severe rhabdomyolysis of unknown origin was made and the patient was admitted to the hospital. Treatment was initiated with intravenous fluid therapy, urine alkalinization and manitol. Forty-eight hours later he developed progressive increase of creatinine values to 5.3 mg/dL, oliguria and cardiac failure and hemodialysis was performed. A total of 6 sessions were required. In the 9th day the patient recovered diuresis. He was discharged with polyuria and decreasing creatinine.
Posttraumatic, ischemic, toxic, infectious, endocrine and immunological etiologies were ruled out. A muscle biopsy from the deltoid muscle was performed. The immunohistochemistry revealed type 2 carnitine-palmitoyl transferase (CPT) deficiency. The familial study disclosed that one sister was also affected.
Metabolic myopathies are a small percentage of rhabdomyolysis causes. However they are a preventable cause of acute renal failure, which very often goes unnoticed. CPT deficiency is the most frequent metabolic myopathy.1, 2 Lipids are an important energy source for resting muscles and during sub-maximal exercise. In case of CPT deficiency fatty acids do not enter in the mitochondria to be oxidized and no energy is obtained. The consequence is muscle destruction or rhabdomyolysis. This condition is the most frequent cause of recurrent myoglobinuria with no clear trigger and should be always suspected in these patients.3
The clinical picture consists of recurrent episodes of muscular weakness, myalgias, rhabdomyolysis or acute renal failure.4, 5 The episodes can be elicited by viral infections, exercise, prolonged fasting or fever. In two thirds of the patients the disease presents in the first or second decade.
The treatment is to avoid the factors that can trigger rhabdomyolysis, like prolonged fasting, to eating a low-fat high-carbohydrate diet, frequent meals and with excessive carbohydrates intake after exercise.
Renal acute failure is due to intratubular deposition of myoglobin. Early volume reposition,6 and urine alkalinization7 with calcium and potassium monitoring are fundamental to prevent it. Manitol use in acute renal failure is controversial, but in case of rhabdomyolysis it appears to reduce interstitial edema and to uptake free radicals. The beneficial effect has been demonstrated in patients with serum CK levels higher than 30,000 U/L.8
