The response of parathyroid hormone to specific changes in either ionized calcium, ionized magnesium, or protein-bound calcium in humans.

Journal Article

Because the effects of specific changes in magnesium or protein-bound calcium on biologic processes in humans have not been clearly defined, we developed an experimental system to specifically lower either ionized calcium, protein-bound calcium, or ionized magnesium. As an indicator of the biological effect of these changes, we measured parathyroid hormone (PTH) in blood. To selectively dilute only one constituent, we infused one of four specially prepared solutions into each of six healthy blood donors following ordinary blood donation. Each donor received at random 450 mL of a different solution at four different blood donations. The respective concentrations of ionized calcium (mmol/L), total magnesium (mmol/L), and albumin (g/L) in these fluids were as follows: control fluid, 1.25, 1.20, 40; no calcium fluid, 0, 1.20, 40; no magnesium fluid, 1.25, 0, 40; no albumin fluid, 1.25, 1.00, 0. Using selective in vivo dilution of the volunteers' blood, we specifically lowered either (1) ionized calcium by 0.07 mmol/L (5.5%), (2) protein-bound calcium by 0.09 mmol/L (10%), or (3) ultrafiltrable magnesium by 0.03 mmol/L (4.8%). While measurements of intact PTH showed that concentrations of PTH in blood did not respond to either decreased ultrafiltrable magnesium or decreased protein-bound calcium, these measurements showed that PTH increased by 400% within 10 minutes in response to decreased ionized calcium.

Full Text

Duke Authors

Cited Authors

  • Toffaletti, J; Cooper, DL; Lobaugh, B

Published Date

  • August 1991

Published In

Volume / Issue

  • 40 / 8

Start / End Page

  • 814 - 818

PubMed ID

  • 1861632

International Standard Serial Number (ISSN)

  • 0026-0495

Language

  • eng

Conference Location

  • United States