PeptideHormone

Parathyroid hormonePTH

The fast-acting hormone that raises blood calcium.

EndogenousEstablished

Identity

Class
Peptide hormone (84 aa)
Source
Parathyroid glands
Receptor
PTH1 receptor (PTH1R), a class B GPCR

Key properties

Molecular weight
~9,425 Da
Half-life (native)
~2–4 min
Model dosing

Approximate values for the native hormone. Engineered analogs are often deliberately larger and far longer-acting.

Mechanism

Released within minutes of a fall in blood calcium, PTH acts on bone and kidney to raise it — mobilizing calcium from bone, increasing renal reabsorption, and stimulating activation of vitamin D. Its effect on bone is paradoxically dual: continuous exposure is catabolic, but intermittent exposure is anabolic.

Reference notes

  • PTH is the body's fastest defense against low blood calcium.
  • Intermittent PTH builds bone; continuous PTH breaks it down — a striking pulsatility effect.
  • It raises calcium partly by activating vitamin D in the kidney.

Selected literature

Curated peer-reviewed reviews, sourced from PubMed. Selected for relevance, not exhaustive — open any entry on PubMed for the full record and its primary citations.

  1. 1.Parathyroid hormone and its related peptides in bone metabolism · Biochemical pharmacology, 2021 · PMID 34224692
  2. 2.Parathyroid hormone: past and present · The Journal of endocrinology, 2005 · PMID 16423810