Prevalence of Low Serum Complement in Lupus Nephritis Patients in Ratchaburi Hospital

Abstract

Objective: This is to determine the prevalence of low serum complement in patients with lupus nephritis and correlation between low serum complement and type of lupus nephritis in Ratchaburi Hospital.

Methods:  A retrospective study based on medical records included patients with lupus nephritis diagnosed by kidney biopsy at Ratchaburi Hospital over a period of 11 years, from 1 January 2011 to 31 December 2021. Demographic data, serum creatinine, urine protein, and serum complement were analyzed by using frequency, percentage, mean, and standard deviation. Correlation between low serum complement and type of lupus nephritis were analyzed by using chi-square statistics.

Results: A total of 128 patients with lupus nephritis had a mean age of 31.6 ± 11.9 years, 83.6% were female. The common type of lupus nephritis was type 4 (54.7%), type 5 (22.6%), and type 3 (18.0%). Among 67 patients with serum complement, the prevalence of low serum C3 in lupus nephritis class 3 was 71.4%, class 4 was 100%, class 5 was 46.2%, and was not found at all in class 6. In addition, the prevalence of low serum C4 in lupus nephritis class 3 was 42.9%, class 4 was 71.8%, class 5 was 23.1%, and was not found at all in class 6. Statistically significant factors associated with proliferative lupus nephritis included younger age, low serum complement C3  which was found in proliferative lupus nephritis 89.1%, and low serum complement C4 was found in proliferative lupus nephritis 91.9%.

Conclusion: This study reported that low serum complement, both C3 and C4, were associated with the severity of inflammation in lupus nephritis. And low serum complement, C3 or C4 statistically significant found in proliferative lupus nephritis, may be chosen as an alternative to renal biopsy in contraindicated cases or there is a rush for treatment.