Measurement of plasma and urinary adrenomedullin in patients with IgA nephropathy

In this study, we measured plasma and urinary adrenomedullin (AM) concentrations in 47 patients with IgA nephropathy. Controls were 39 healthy volunteers. Plasma and urinary AM values were measured by specific radioimmunoassay. The plasma AM concentrations were higher, and the urinary AM levels were lower in patients with IgA nephropathy than in healthy volunteers. Plasma AM concentrations showed a positive correlation with serum creatinine and blood urea nitrogen, whereas urinary AM levels correlated negatively with serum creatinine and blood urea nitrogen. The plasma AM concentrations showed a positive correlation with fractional excretions of sodium and potassium. Renal biopsy specimens of patients without renal failure were scored for activity (percentage of glomeruli demonstrating cellular crescent formation, degree of mesangial proliferation and interstitial infiltration; total score = 9). Urinary AM levels were shown to be lower in the group with a high activity (score 3-9) as compared with the group with a low activity (score 0-2) based on renal biopsy. Thus, urinary levels of AM are affected by the degree of the activity in IgA nephropathy, and AM may participate in the pathophysiology of IgA nephropathy.