[Medical rhabdomyolysis in the elderly]

To investigate the characteristics of medical rhabdomyolysis (RM) in the elderly, as well as differences compared with those observed in younger patients.

Prospective study of 56 elderly patients (> or = 65 years) with RM and 73 younger patients (> 7 years and < 65 years) with RM for 43 months. The RM characteristics were analyzed in the elderly group (ERM) and compared with those in the younger group (YRM).

Fifty-six elderly patients with RM (38 males and 18 females, with a mean age of 76.3 +/- 7.6 years; range: 65-92 years) and 73 younger patients (57 males and 16 females, with a mean age of 37.9 +/- 15.6 years; range: 13-63 years), made up the 129 patients in the study. The most common cause for RM in the ERM was muscle compression due to immobilization and the multicausative group, both with 9 (16%) cases, followed by respiratory infection with 8 (14.2%) cases. In the YRM, the most common cause was physical exertion with 15 patients (20.5%) and multicausative with 18 patients (24.6%). Myalgia predominated in the YRM group, with 25 vs. 9 (odds ratio [OR]: 2.7; 95% confidence interval [CI]: 1.0-7.3; p < 0.05). Acute renal failure (ARF) occurred in 13 patients in the ERM group compared with 4 in the YRM group (OR: 5.2; 95% CI: 1.4-23; p < 0.01). In the logistic regression analysis an association was found between hypoalbuminemia and ARF for the ERM group. In the presence of ARF, both ERM and YRM had decreased serum calcium levels, deeper in YRM and more prolonged in the ERM. Six patients in the ERM died, and four of them had developed ARF. In contrast, none of the two deceased patients in the YRM had the complication of ARF.

Almost half of cases of RM occur in elderly patients, which is mostly due to muscle compression and infections, particularly in the respiratory tract. Symptoms are usually mild and the development of ARF is more common than in younger patients, and its presence is associated with hypoalbuminemia. Hypocalcemia associated with ARF was less deep in the elderly, but more persistent than in younger patients. Most deceased patients in the elderly group previously developed ARF.