Can we use serum and urine immunoglobulin levels as biomarkers in patients with glomerulonephritis?

Introduction: Non-invasive biomarkers for assessing disease activity and progression are continuously being sought, but difficult to validate. For glomerulonephritis (GN), various molecules in both blood and urine are undergoing stringent research. Immunoglobulin (Ig) levels have also been sought as potential biomarkers with variable results. Objectives: We aimed at determining the utility of serum and urine Ig levels to ascertain severity of proteinuria and renal functions in GN patients. Materials and Methods: Blood and urine of 25 GN patients and 13 healthy controls were tested for Ig levels including IgG, IgM, IgA and IgE. The degree of proteinuria, renal functions and histopathological features were recorded from the case files of these patients. Results: The mean serum IgM and IgA levels were significantly high in GN patients compared to controls. However, two patients had high IgM and one had high IgA levels. Three patients had low IgG levels but did not correlate with urinary loss. Moreover IgGuria was not different in patients with or without severe disease. In patients with acute GN IgMuria was more prevalent. While in chronic GN, IgAuria was more common. Mean serum IgE levels were more in healthy controls and did not correlate with renal dysfunction. However, mean IgEuria was more pronounced in patients with renal dysfunction Conclusion: The utility of serum and urine Ig as biomarkers of disease activity and progression in GN patients is still debatable and require further studies. Abnormal levels of these proteins in blood of GN patients require further workup to rule out any concomitant pathology.