Association of relatively low serum parathyroid hormone with malnutrition-inflammation complex and survival in maintenance hemodialysis patients.
BACKGROUND
Low serum parathyroid hormone (PTH) has been implicated as a primary biochemical marker of adynamic bone disease in individuals with chronic kidney disease (CKD) who undergo maintenance hemodialysis (MHD) treatment. We hypothesized that the malnutrition-inflammation complex is associated with low PTH levels in these patients and confounds the PTH-survival association.


METHODS
We examined 748 stable MHD outpatients in southern California and followed them for up to 5 years (October 2001-December 2006).


RESULTS
In 748 MHD patients, serum PTH <150pg/mL was more prevalent among non-blacks and diabetics. There was no association between serum PTH and coronary artery calcification score, bone mineral density, or dietary protein or calorie intake. Low serum PTH was associated with markers of protein-energy wasting and inflammation, and this association confounded the relationship between serum PTH and alkaline phosphatase. Although 5-year crude mortality rates were similar across PTH increments, after adjustment for the case-mix and surrogates of malnutrition and inflammation, a moderately low serum PTH in 100-150pg/mL range was associated with the greatest survival compared to other serum PTH levels, i.e., a death hazard ratio of 0.52 (95% confidence interval: 0.29-0.92, p<0.001) compared to PTH of 300-600pg/mL (reference).


CONCLUSIONS
Low serum PTH may be another facet of the malnutrition-inflammation complex in CKD, and after controlling for this confounder, a moderately low PTH in 100-150pg/mL range appears associated with the greatest survival. Limitations of observational studies should be considered.
Dukkipati
Ramanath
R
Harold Simmons Center for Chronic Disease Research and Epidemiology, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA 90502, USA.
Kovesdy
Csaba P
CP
Colman
Sara
S
Budoff
Matthew J
MJ
Nissenson
Allen R
AR
Sprague
Stuart M
SM
Kopple
Joel D
JD
Kalantar-Zadeh
Kamyar
K
D000469:Alkaline Phosphatase / Q000097:blood; D015415:Biomarkers / Q000097:blood; D015519:Bone Density / Q000502:physiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007249:Inflammation / Q000097:blood* / Q000401:mortality; D007676:Kidney Failure, Chronic / Q000097:blood* / Q000150:complications / Q000401:mortality*; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood*; D011502:Protein-Energy Malnutrition / Q000097:blood* / Q000401:mortality; D006435:Renal Dialysis; D016019:Survival Analysis
D015415:Biomarkers; D010281:Parathyroid Hormone; D000469:Alkaline Phosphatase