Function of parathyroid glands in kidney transplant patients--diagnostic value of CAP and CIP.
OBJECTIVE
As shown in the last four years, Nichols assay for the estimation of "intact" parathyroid hormone (i-PTH) apparently overestimates parathyroid gland function by recognizing both the whole PTH- 1-84 molecule (identified as a cyclase activating PTH - CAP) and N-truncated fragments of PTH-7-84 (identified as a cyclase inactive PTH - CIP). As PTH-1-84 and PTH-7-84 are presumed to show antagonistic effects on calcaemia and bone turnover, we aimed to assess the relationship between PTH-1-84 and PTH-7-84 plasma levels respectively and bone turnover markers in kidney transplant patients.


METHODS
52 patients and 17 healthy subjects were examined at least 4 years after renal transplantation. In all subjects the following parameters were assessed: bone mineral density (BMD) of the total body, L2-L4 vertebrae and femoral neck (DEXA), serum total PTH (i-PTH) and PTH-1-84 level, as well as the difference between total PTH and PTH-1-84 (reported as PTH-7-84), activity of alkaline phosphatase (AP), serum concentration of collagen type I cross-linked C-telopeptide, osteocalcin (OC), creatinine (creat), 25-OH-D, total calcium (Ca(total)) and phosphorus (P) concentration.


RESULTS
Tx patients were characterized by significantly elevated plasma values of all examined parameters except activity of AP and plasma level of Ca, P and 25-OH-D. Both in HS and Tx patients a significant positive correlation was found between plasma concentration of PTH-1-84 and PTH-7-84. In addition in Tx patients both PTH-1-84 and PTH-7-84 showed a significant positive correlation with plasma creatinine, OC, AP and Ctx and a negative one with BMD T score, while in HS PTH-1-84 and PTH-7-84 were positively correlated with OC and AP and negatively with Ca and BMD (borderline significance).


CONCLUSIONS
Presence of highly significant correlations between PTH-1-84 or PTH-7-84 and markers of both osteogenesis and osteolysis respectively is not consistent with a diagnostic superiority of PTH- 1-84 and PTH-7-84 over total PTH estimation in patients 4 or more years after renal transplantation.
Spiechowicz
Urszula
U
Department of Nephrology, Endocrinology and Metabolic Diseases, Silesian University Medical School, Katowice, Poland.
Kokot
Franciszek
F
Wiecek
Andrzej
A
D000328:Adult; D000469:Alkaline Phosphatase / Q000097:blood; D015415:Biomarkers / Q000097:blood*; D015519:Bone Density; D016723:Bone Remodeling; D016022:Case-Control Studies; D003094:Collagen / Q000097:blood; D024042:Collagen Type I; D003404:Creatinine / Q000097:blood; D005260:Female; D006801:Humans; D016030:Kidney Transplantation; D008297:Male; D015675:Osteocalcin / Q000097:blood; D010280:Parathyroid Glands / Q000503:physiopathology*; D010281:Parathyroid Hormone / Q000097:blood*; D010446:Peptide Fragments / Q000097:blood*; D010455:Peptides / Q000097:blood
D015415:Biomarkers; D024042:Collagen Type I; D010281:Parathyroid Hormone; D010446:Peptide Fragments; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; C414937:parathyroid hormone (7-84); D015675:Osteocalcin; D003094:Collagen; D003404:Creatinine; D000469:Alkaline Phosphatase