Hyponatremia in patients with systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic multisystem autoimmune disease with a highly variable clinical course1,2. During the course of the disease, decreased serum levels of C3, C4 and high anti-double stranded (anti-ds) DNA antibody titers are reported to be associated with the disease activity and poor survival3. Hyponatremia is known to be one of the most common electrolyte abnormalities and can cause seizures, brain edema, encephalopathy, and even death4,5. Hyponatremia has been reported to be poor clinical outcome such as mortality in general population, dialyzed patients and those with heart failure, cirrhosis and sepsis6,7,8. However, the incidence and clinical significance of hyponatremia has not been studied in rheumatic diseases including SLE and only some case reports of hyponatremia have been reported in SLE9,10. Also, there has been no report describing the relationship between the degree of hyponatremia and the disease activity in both childhood and adulthood SLE. Therefore, the aim of this study was to evaluate the clinical and laboratory characteristics related to disease activity in children and adults with SLE and determine whether decreased serum sodium concentration could be associated with the disease activity in SLE.