Immunoreactive parathyroid hormone

Immunoreactive parathyroid hormone concentrations may be increased by anticonvulsants, while bone mineral content is reduced. Hypocalcemia and osteopenia can occur, despite normal serum concentrations of active vitamin D metabolites, suggesting that they may be independent of drug effects on vitamin D metabolism. Bone biopsies have shown increased osteoid but normal calcification front formation, accelerated rate of mineralization, and reduced mineralization lag time, suggesting increased skeletal turnover rather than osteomalacia (96). The risk of age-related fractures in drug-treated epileptic patients is not greatly increased (97). 

Figure 9. Inverse correlation between serum calcium concentration and serum immunoreactive parathyroid hormone (iPTH) level when patient was on lithium (Li) treatment (solid line). The square denotes the normal range for serum calcium and iPTH. Solid circles denote when patient was taking lithium and open circles when lithium had been withdrawn. HCTZ = hydrochlorothiazide.

Endres DB, Morgan CH, Garry PJ, Omdahl JL. Age-related changes in serum immunoreactive parathyroid hormone and its biological action in healthy men and women. J Clin Endocrinol Metab 1987 65 724-31. 

Gallagher JC, Riggs BL, Jerpbak CM, Arnaud CD. The effect of age on serum immunoreactive parathyroid hormone in normal and osteoporotic women. J Lab Clin Med 1980 95 373-85. 

Papantoniou NE, Papapetrou PD, AntsakUs AJ, Kon-toleon PE, Mesogitis SA, Aravantinos D. Circulating levels of immunoreactive parathyroid hormone-related protein and intact parathyroid hormone in human fetuses and newborns. Eur J Endocrinol 1996 134 437-42. 

Immunoreactive parathyroid hormone (iPTH) was analyzed by mean of radioimmunoassay method, utilizing specific antibody for C-terminal fragment (ISO - TEX Diagnostics, Friedswood Texas, U.S.A.). (Normal range in our laboratory is 0.4 - 1.4 ng/ml). 

Immunoreactive Forms of Circulating Parathyroid Hormone in Primary and Ectopic Hyperparathyroidism". J. Clin. Invest. (1974), 175-181. 

Rubin LP, Posillico JT, Anast CS, Brown EW. Circulating levels of biologically active and immunoreactive intact parathyroid hormone in human newborns. Pediatr Res 1991 29 201-7. 

FIGURE 11.21 Immunoreactivity for parathyroid hormone (A) in primary mediastinal parathyroid carcinoma (B). 

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