These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Non-suppressible parathyroid hormone secretion is related to gland size in uremic secondary hyperparathyroidism.
    Author: Indridason OS, Heath H, Khosla S, Yohay DA, Quarles LD.
    Journal: Kidney Int; 1996 Nov; 50(5):1663-71. PubMed ID: 8914034.
    Abstract:
    To determine the relative importance of parathyroid gland enlargement and alterations in calcium sensing (set-point changes) in the pathogenesis of uremic secondary hyperparathyroidism (2 degrees HPT), we investigated the relationship between estimates of parathyroid gland size and calcium-mediated parathyroid hormone (PTH) suppression in 19 normocalcemic 2 degrees HPT patients on chronic maintenance hemodialysis. We compared our results to calcium-mediated PTH suppression in 12 normal volunteers, 12 patients with familial benign hypocalciuric hypercalcemia (FBHH), a disorder of abnormal calcium sensing, and 9 subjects with primary hyperparathyroidism (1 degree HPT), which is characterized by both calcium set-point abnormalities and parathyroid gland enlargement. We found that the 2 degrees HPT group displayed a distinctive pattern of calcium-mediated PTH suppression characterized by a failure to normally suppress PTH at supraphysiologic ionized calcium concentrations, similar to 1 degree HPT, but without the rightward shift of the calcium-PTH suppression curve that characterizes calcium sensing abnormalities in FBHH and 1 degree HPT. In the patients with 2 degrees HPT, hypercalcemic suppression resulted in an ending PTH (as a percent of baseline) that was significantly higher (39.8 +/- 4.47%), and a slope of the calcium-PTH suppression curve that was significantly less negative (-4.8 +/- 0.53), compared to respective values of 19.4 +/- 1.81% (P = 0.0009) and -9.0 +/- 1.02 (P = 0.001) in normals and 19.1 +/- 2.49% (P = 0.001) and -9.6 +/- 1.11 (P = 0.0006) in FBHH. Values of ending PTH and slope in 2 degrees HPT patients, however, were similar to those found in 1 degree HPT (49.8 +/- 6.35%, P = 0.21 and -4.5 +/- 0.74, P = 0.72). The ionized calcium concentration required to attain half maximal PTH suppression (EC50) in 2 degrees HPT (1.20 +/- 0.02 mmol/liter) was not significantly different from normals (1.25 +/- 0.01 mmol/liter, P = 0.12) but was significantly less than in 1 degree HPT (1.52 +/- 0.02 mmol/liter, P < 0.0001) and in FBHH (1.44 +/- 0.02 mmol/liter, P < 0.0001). More importantly, we found a significant linear correlation between the natural logarithm of gland size and ending PTH suppression (r = 0.71, P < 0.001) and slope of the calcium-PTH curve (r = 0.67, P = 0.002) in 2 degrees HPT. Thus, calcium non-suppressible PTH secretion in 2 degrees HPT does not represent a simple set-point error, but rather correlates with the degree of parathyroid gland enlargement.
    [Abstract] [Full Text] [Related] [New Search]