Differences in bone turnover and intact PTH levels between African American and Caucasian patients with end-stage renal disease.
BACKGROUND
Evidence derived from healthy subjects suggests that African Americans have higher serum parathyroid hormone (PTH) levels and decreased bone responsiveness to PTH than Caucasians. African American patients with end-stage renal disease (ESRD) also have higher serum PTH than Caucasians. Studies that correlate intact PTH (iPTH) levels with bone turnover in ESRD patients were performed in a predominantly Caucasian population.


METHODS
In this study, serum iPTH and bone histomorphometric data were analyzed for racial differences in 76 ESRD patients (Caucasian = 48, African Americans = 28). Bone turnover was determined by histomorphometric measurement of activation frequency in all patients.


RESULTS
Age, duration of dialysis, and calcium and phosphorus levels were similar between the two groups. iPTH levels (pg/mL; mean +/- SE) were significantly higher in the African American group (534 +/- 79 vs. 270 +/- 46, P < 0.01). Also, alkaline phosphatase levels (IU/L) were significantly higher in the African American group (162 +/- 31 vs. 144 +/- 43, P < 0.01). Correlations between PTH levels and activation frequency were r = 0.60, P < 0.01 in Caucasians and r = 0.22, P = NS in African Americans. The mean PTH level in African American patients with histologic findings of low bone turnover was 460 +/- 115 vs. 168 +/- 41 in Caucasian patients with similar bone turnover (P < 0.01). In patients with low bone turnover, African Americans had significantly higher osteoid volume and thickness, number of osteoblasts and osteoclasts, erosion surface, peritrabecular fibrosis, and single-label surface than Caucasians. However, erosion depth, bone formation rate per osteoblast and mineralization apposition rate were similar between the two groups.


CONCLUSIONS
There is no correlation between iPTH and bone turnover in African Americans with ESRD. A substantial number of African American patients with low bone turnover have very high serum PTH levels. Bone histomorphometric results reveal differences in remodeling dynamics and responses to PTH between African American and Caucasian patients. Further studies utilizing newer PTH measurement assays are needed to better delineate the correlation between PTH and bone turnover in the various racial groups.
Sawaya
B Peter
BP
Division of Nephrology, Bone and Mineral Metabolism, Department of Medicine, University of Kentucky, Lexington, Kentucky 40536-0298, USA. besawa0@uky.edu
Butros
Rezkalla
R
Naqvi
Shehzab
S
Geng
Zhaopo
Z
Mawad
Hanna
H
Friedler
Robert
R
Fanti
Paolo
P
Monier-Faugere
Marie-Claude
MC
Malluche
Hartmut H
HH
D001741:Black or African American; D016723:Bone Remodeling; D001842:Bone and Bones / Q000378:metabolism / Q000473:pathology; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000208:ethnology / Q000378:metabolism* / Q000628:therapy; D008297:Male; D008875:Middle Aged; D010006:Osteoblasts / Q000378:metabolism / Q000473:pathology; D010281:Parathyroid Hormone / Q000097:blood*; D006435:Renal Dialysis; D044465:White People
D010281:Parathyroid Hormone