Neuropeptide Y and markers of osteoblast activity in dialysis patients: a cross-sectional study.
BACKGROUND
In mice, neuropeptide Y (NPY) decreases bone turnover by means of a parathyroid hormone-independent effect on osteoblast activity.


METHODS
Cross-sectional study.


METHODS
We studied the relationship between levels of NPY and biomarkers of osteoblast activity in 161 nondiabetic patients with end-stage renal disease (131 patients, hemodialysis; 30 patients, continuous ambulatory peritoneal dialysis).


METHODS
We performed an analysis of demographic and clinical variables associated with NPY as a dependent variable and a second analysis testing the association of NPY (as an independent variable) with markers of osteoblast activity.


RESULTS
Peritoneal dialysis as treatment modality (beta = 0.37; P < 0.001) and longer duration of dialysis therapy (beta = 0.24; P < 0.01) were independently related to plasma NPY. NPY level was related inversely (P < 0.001) to serum alkaline phosphatase and bone alkaline phosphatase levels (P = 0.01). The NPY-alkaline phosphatase link was confirmed in a multiple regression analysis adjusting for a series of potential confounders, including parathyroid hormone. In a categorical analysis in which the study population was divided according to NPY quartiles, the proportion of patients with low alkaline phosphatase levels was lowest in the first 2 NPY quartiles (26%) and highest in NPY quartile 4 (80%; P < 0.001), and this association held true in a multiple logistic regression analysis, indicating that the risk of low alkaline phosphatase level increases in parallel with NPY level.


CONCLUSIONS
The hypothesis generated by this cross-sectional study needs to be confirmed in cohort studies.


CONCLUSIONS
The inverse relationships between levels of NPY and biomarkers of bone turnover support the hypothesis that NPY may be implicated in low bone turnover in dialysis patients by a central parathyroid-independent mechanism.
CNR-IBIM, National Research Council-Institute of Biomedicine, Clinical Epidemiology and Physiopathology of Renal Diseases and Hypertension, Reggio Calabria, Italy.
Vincenzo
V
Panuccio
Sebastiano
S
Cutrupi
Patrizia
P
Pizzini
Francesca
F
Mallamaci
Giovanni
G
Tripepi
Carmine
C
Zoccali
D000368:Aged; D000469:Alkaline Phosphatase / Q000097:blood; D015415:Biomarkers / Q000378:metabolism*; D001847:Bone Diseases / Q000097:blood* / Q000209:etiology; D001842:Bone and Bones / Q000201:enzymology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000150:complications / Q000378:metabolism* / Q000503:physiopathology* / Q000628:therapy; D008297:Male; D008875:Middle Aged; D009478:Neuropeptide Y / Q000097:blood*; D010006:Osteoblasts / Q000502:physiology*; D010530:Peritoneal Dialysis; D012044:Regression Analysis; D006435:Renal Dialysis
D015415:Biomarkers; D009478:Neuropeptide Y; D000469:Alkaline Phosphatase