Adiponectin is markedly increased in patients with nephrotic syndrome and is related to metabolic risk factors

Adiponectin (ADPN), the gene product of apM1, is the most abundant secretory protein of the adipose tissue in human plasma. Altered regulation (reduced synthesis) of this substance may be relevant to endothelial dysfunction and cardiovascular complications in patients with ESRD.

We investigated the relationship between plasma ADPN, glomerular filtration rate (GFR) (plasma iohexol clearance), and metabolic risk factors in 16 patients with nephrotic syndrome, in 25 patients with chronic nephropathies without nephrotic syndrome, and in 31 healthy subjects.

Plasma ADPN was much higher (P < 0.01) in patients with nephrotic syndrome (24.4 +/- 14.9 microg/mL) than in patients with chronic nephropathies without nephrotic syndrome (12.3 +/- 7.2 microg/mL) and healthy subjects (5.9 +/- 2.6 microg/mL). In the aggregate 24-hour, proteinuria (r = 0.53, P < 0.01) and serum cholesterol (r = 0.53, P < 0.01) were strong and direct correlates of plasma ADPN, while serum albumin correlated inversely (r = -0.46, P < 0.01) with this protein. Proteinuria appeared to be an important confounder of the relationship between ADPN and the GFR because in the whole patient population (with and without nephrotic syndrome), this relationship emerged only after data adjustment for 24-hour proteinuria (partial r = -0.31, P = 0.05), while no such relationship was demonstrable on crude data analysis (r = 0.03, P = 0.87).

ADPN is markedly increased in patients with nephrotic syndrome, and proteinuria is strongly related to circulating ADPN in patients with nephrotic and non-nephrotic renal diseases. The relationships between plasma ADPN, serum cholesterol, and serum albumin suggest that this adipocyte protein may serve to mitigate endothelial damage triggered by dyslipidemia and other risk factors in patients with chronic renal diseases.