Abstract:

Objective To investigate the clinical features of renal involvement in patients with polymyositis and dermatomyositis. Methods The clinical data of patients with polymyositis and dermatomyositis confirmed from January 2003 to December 2008 were collected, and the incidence, severity and prognosis of renal injury were retrospectively analysed. Results Of the 146 patients confirmed with polymyositis and dermatomyositis, 107(73.29%) visited Department of Dermatology first, while only 4(2.74%) visited Department of Nephrology first. Thirty patients (20.5%) were found to suffer from various degrees of renal injury, which were characterized by single haematuria in 10 patients (33.33%), single proteinuria in 6 patients (20.00%), proteinuria complicated with haematuria in 13 patients (43.33%), hypertension in 7 patients (23.33%) and edema in 3 patients. In 10 patients with single haematuria, 7 had microscopic haematuria >+++. In 11 patients undergoing 24 h urinary protein measurement, 7 had urinary protein <1 g/d. Renal biopsy was performed in all the 4 patients who visited Department of Nephrology first, and it was revealed that two patients had segmental glomerulosclerosis, 1 patient had glomerular minor lesion, and the other patient had lupus nephritis. All patients were treated with immunosuppressant. One patient was cured, 23 patients did not deteriorate or got better, and the effective rate was 80.00%. Five patients died (multiple organ failure in 4 patients and lung cancer in 1 patient), and the mortality rate was 16.67%. Conclusion Renal injury in patients with polymyositis and dermatomyositis is rare, which is characterized by obvious microscopic haematuria, small amount of proteinuria, mild to moderate hypertension and mild renal function disorder, and patients may have favorable response to immunosuppressant.

Key words: polymyositis, dermatomyositis, chronic kidney disease