Impact of parathyroid hormone on bone density in long-term renal transplant patients with good graft function.
BACKGROUND
It remains unknown whether low-grade hyperparathyroidism persisting beyond the first year postrenal transplantation has any impact on bone density.


METHODS
Parathyroid hormone (PTH), glomerular filtration rate (GFR), and bone density (by dual-energy x-ray absorptiometry [DXA]) were monitored in the follow-up of our transplant patients. Of 260 long-term renal transplant patients, 41 fulfilled the following criteria: Two DXA measurements performed at least five years apart (median 6.8 years, range 5-9); GFR>or=35 ml/min per 1.73 m body surface area (median 50, range 35-76); no bisphosphonate treatment or parathyroidectomy in the study period.


RESULTS
In all, 40% had mean PTH values above the normal limit 6.9 pmol/L (65 pg/ml), and the range was 0.9-17 pmol/L. In the first DXA, 8 of 41 patients had osteoporosis and 17 more had osteopenia. Hip bone density Z-score was -0.60 SD, range (-2.6 to +2.3). The absolute median value (g/cm) remained unchanged until the second DXA, but among patients there was a variation which ranged from -2.3% to +1.7% per year. In a simple linear regression analysis, these changes were significantly correlated to mean PTH (r=0.16, P=0.010). Median lumbar spine bone density was also reduced in the first DXA and was not different at follow-up, but with this variable individual changes did not correlate to mean PTH.


CONCLUSIONS
Bone density is often reduced and PTH remains elevated in long-term renal transplant patients with good transplant function. Slight to moderate elevation of PTH is associated with reduction in hip bone mineral density.
Akaberi
Shahriar
S
Department of Nephrology, University Hospital, Lund, Sweden. shahriar.akaberi@skane.se
Lindergård
Birger
B
Simonsen
Ole
O
Nyberg
Gudrun
G
D015502:Absorptiometry, Photon; D000328:Adult; D000368:Aged; D015519:Bone Density; D005500:Follow-Up Studies; D005919:Glomerular Filtration Rate; D006801:Humans; D006980:Hyperthyroidism / Q000453:epidemiology / Q000503:physiopathology*; D016030:Kidney Transplantation / Q000502:physiology*; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood*; D012044:Regression Analysis; D013997:Time Factors
D010281:Parathyroid Hormone