Glomerulonephritis in Mixed Connective Tissue Disease

Objective: To study clinical and serological features of mixed connective tissue disease (MCTD) patients, determine the frequency of glomerulonephritis (GN) and its association with clinical and immunological disease parameters.Methods: This study included 23 patients with MCTD. A systematic complete evaluation including full history taking, thorough clinical examination and laboratory investigations including those to assess renal function were performed to all patients. Renal biopsy was performed for patients with clinical and/or laboratory evidence of renal affection. Immunological markers were assayed.Results: The most common clinical manifestations of MCTD were arthritis/arthralgia (86.9%), Raynaud s phenomenon (82.6%) and swollen hands (82.6%). Anti U1 RNP and ANA were detected in all patients. Anti ds DNA antibodies in 8.6%, anti Sm antibodies in 26%, MPO-ANCA in 4.3% and hypocomplementemia in 56.5%. Nephritis was detected in 8/23 (34.7%) patients. Among the 8 patients 5, (62.5%) had nephrotic syndrome, two had hypertension. Abnormalities in urine analysis were detected in the eight patients. Abnormal kidney function tests were recorded in 4/8 (50%) of cases. Renal biopsy studies showed membranous GN in 5/8 in (62.5%) cases and mesangial proliferative GN in 37.5% of cases. MCTD patients with GN tended to have more severe arthritis as evidenced by higher articular index and more swollen joints, more serositis, more sicca symptoms, more damage index and more association with anti Sm antibodies than patients without GN.Conclusion: Arthritis, Raynaud s phenomenon and swollen hands are the most common manifestations of MCTD. Nephritis is not uncommon, occurring in more than one third of cases. It is mainly of the membranous GN. Patients with GN had more severe arthritis, systemic manifestations and anti- Sm antibodies than patients without GN.