A STUDY ON THE BIOLOGICAL SIGNIFICANCE OF MIDREGION AND INTACT PARATHYROID-HORMONE IN HEMODIALYSIS-PATIENTS

In this study, we investigated the relationship between the concentrat ions of intact parathyroid hormone (i-PTH) and midregion PTH (m-PTH) m easured by an immunoradiometric assay and a radioimmunoassay, respecti vely, versus various demographic and biochemical parameters, bone mine ral density (BMD) of the lumbar spine (LS) and radius, and the radiogr aphic findings of osteosclerosis and aortic calcification in hemodialy sis (HD) patients. m-PTH correlated positively and more significantly with serum calcium (Ca), serum phosphorus (P), Ca-P solubility product s (Ca x P) and LS-BMD than i-PTH did (P=0.024 vs. 0.531, 0.001 vs. 0.0 61, 0.0001 vs. 0.125, and 0.017 vs. 0.284, respectively). A positive c orrelation between the percent changes in serum P over the 1-month mea surement period and those in m-PTH rather than in i-PTH was also obser ved (P=0.021 vs. 0.869). These data indicate that m-PTH is distinct fr om i-PTH in its positive correlation with serum Ca, serum P, Ca Y P an d LS-BMD in HD patients. Since m-PTH is known to consist mostly of the midregion and carboxyl-terminal fragments of PTH in HD patients, the present study suggests that these PTH fragments may be biologically si gnificant in the patients in vivo.