Parathyroid Gland and Hormone
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Introduction
PTH's primary function is to increase ionized Ca2+ levels in the plasma. If Ca2+ is low, PTH is elevated, while high Ca2+ results in a reduction in PTH.
PTH acts to increase calcium in a number of ways:
- increases release from bone by stimulating osteoclast number and activity
- stimulates reabsorption of Ca2+ and inhibits reabsorption of phosphate in the kidney's proximal and distal tubules
- stimulates renal synthesis of 1,25(OH2)D3 (through activity of 1α-hydroxylase), increasing intestinal Ca2+ and phosphate absorption (takes 24-48 hours)
Hyperparathyroidism causes an increase in serum calcium but is often asymptomatic.
Resources and References
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