Pregnancy-associated plasma protein A in dialysis patients

Pregnancy-associated plasma protein A (PAPP-A) was recently described as a new marker of cardiovascular events and of inflammation in uremic patients. The aim of this study was to determine levels of PAPP-A in chronic dialysis patients and its possible relationships with renal osteodystrophy.

A total of 99 adult chronic hemodialysis patients, 14 peritoneal dialysis patients and 41 control subjects were included in the study. Serum PAPP-A, intact parathormone (iPTH), calcium, phosphorus and alkaline phosphatase (ALP) were measured. The correlations between PAPP-A and iPTH, calcium, phosphorus and ALP were determined.

PAPP-A levels were significantly higher in peritoneal dialysis [4.5 (3.2-6.7) mU/L, median (interquartile range)], and hemodialysis patients [4.7 (3.8-6.5) mU/L] in comparison to control subjects [3.4 (3.0-5.0) mU/L] (p<0.05). In hemodialysis patients, post-dialysis PAPP-A levels [6.2 (4.7-9.4) mU/L] were significantly higher than pre-dialysis levels [4.7 (3.8-6.5) mU/L] (p<0.05). There was a weak but statistically significant positive correlation between serum PAPP-A and iPTH (r=0.216; p=0.041) and ALP (r=0.205; p=0.044) in the hemodialysis group. Correlation between the duration of dialysis therapy and PAPP-A levels was also significant (r=0.267; p=0.008) in the hemodialysis group.

PAPP-A levels are elevated in acute coronary syndromes and are closely related to inflammation and oxidative stress. We conclude that PAPP-A levels are increased in dialysis patients and may reflect a greater degree of chronic inflammation than osteodystrophy in uremic patients.