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The 84-residue calcium hormone behind teriparatide, abaloparatide and palopegteriparatide — and the one whose intermittent pulses build bone while continuous exposure dissolves it.
Also known as: PTH · PTH(1-84) · Parathormone · Recombinant human parathyroid hormone (1-84)
Part of the Foundational & therapeutic peptides cluster
Overview
Parathyroid hormone (PTH) is the 84-amino-acid peptide the parathyroid glands secrete to raise blood calcium: it enhances renal calcium reabsorption, increases active vitamin D production for intestinal absorption, and mobilises calcium from bone. Recombinant PTH(1-84) has been used as replacement therapy in hypoparathyroidism, and its N-terminal fragment is the basis of the osteoporosis drugs teriparatide and abaloparatide.
Source & context
Biological / chemical source: Parathyroid glands (human); recombinant full-length peptide for therapeutic use
Primary research or clinical context: Endogenous hormone; recombinant human PTH(1-84) has been used as replacement therapy in hypoparathyroidism, and shortened analogues (teriparatide, abaloparatide) are approved for osteoporosis
What parathyroid hormone is
Parathyroid hormone is “the major secretory product of the parathyroid glands, and in hypocalcemic conditions, can enhance renal calcium reabsorption, increase active vitamin D production to increase intestinal calcium absorption, and mobilize calcium from bone by increasing turnover, mainly but not exclusively in cortical bone” (Goltzman, Endocrinology and Metabolism Clinics of North America 2018). It is an 84-residue single-chain peptide — large enough that, as the LactMed database notes, it is “a large protein molecule” whose passage into milk and absorption by an infant are expected to be minimal (LactMed, 2023). Its job is to keep extracellular calcium in a narrow band, in concert with 1,25-dihydroxyvitamin D and calcium itself (Goltzman, Endocrinology and Metabolism Clinics of North America 2021).
Physiology and control
The parathyroid glands sense calcium directly and secrete PTH when it falls. The hormone then acts on kidney and bone within minutes to hours, and on the gut indirectly by raising active vitamin D. Extracellular calcium “is normally tightly regulated by parathyroid hormone (PTH), 1,25-dihydroxyvitamin D, as well as by calcium ion (Ca++) itself”; dysregulated PTH production leading to hypercalcaemia “occurs most commonly in sporadic primary hyperparathyroidism” (Goltzman, Endocrinology and Metabolism Clinics of North America 2021). The opposite failure, hypoparathyroidism, leaves the body unable to defend calcium, and it is there that PTH itself “has found clinical use as replacement therapy” (Goltzman 2018).
Receptor signalling — including from inside the cell
PTH acts on the type 1 PTH receptor, a class B G-protein-coupled receptor also used by PTH-related protein. The canonical model of receptor activation assumes signalling occurs only at the cell surface and is switched off quickly by receptor phosphorylation; work on the PTH receptor has shown that it can continue to signal after internalisation, from endosomes (Peña, American Journal of Physiology — Cell Physiology 2022). That difference in signalling duration is one proposed explanation for why continuous PTH exposure and brief pulses have opposite effects on bone, the pharmacological principle behind once-daily osteoporosis analogues.
From hormone to drug: the 1–34 fragment and beyond
The N-terminal 34 residues of PTH carry full receptor activity, and that fragment, made recombinantly, is teriparatide, an approved bone-building osteoporosis medicine. Abaloparatide is a 34-residue analogue of the related PTH-related protein. Palopegteriparatide is a long-acting prodrug of the 1–34 fragment developed for hypoparathyroidism. The full-length recombinant human PTH(1-84) has also been used therapeutically — LactMed records a case of maternal use during breastfeeding with no harm to the infant (LactMed, 2023) — as replacement in hypoparathyroidism (Goltzman 2018). Each of those analogues has its own profile on this site; this page is the reference sequence they descend from.
| Peptide | Relation to PTH | Length |
|---|---|---|
| PTH (1-84) | The hormone itself; recombinant form used in hypoparathyroidism | 84 aa |
| Teriparatide | PTH(1-34), recombinant | 34 aa |
| Abaloparatide | PTHrP(1-34) analogue | 34 aa |
| Palopegteriparatide | Long-acting prodrug of PTH(1-34) | 34 aa (+ carrier) |
Why intermittent and continuous PTH do opposite things
The same hormone that mobilises calcium from bone when secreted continuously — the mechanism of bone loss in hyperparathyroidism — increases bone formation when given as a brief daily pulse, which is how teriparatide works. Whether PTH controls bone quality as well as quantity has been debated (Shoback, Endocrine 2017). The endosomal-signalling findings offer a mechanistic thread: pulse and continuous exposure produce different signalling durations at the receptor (Peña 2022). Readers comparing the PTH-receptor drugs should keep this pharmacology in mind, because it explains why dose timing, not just dose, defines the outcome.
Regulatory status
PTH is an endogenous hormone. Recombinant human PTH(1-84) is a therapeutic product used as replacement therapy in hypoparathyroidism per the physiology literature in the evidence pack; the pack does not carry the specific product approvals, so they are not restated here. Teriparatide and abaloparatide are approved osteoporosis medicines, and palopegteriparatide is an approved hypoparathyroidism treatment, each documented on its own profile. ClinicalTrials.gov listed 619 registered studies naming parathyroid hormone as an intervention at the September 2026 snapshot, a footprint that reflects decades of endocrine research rather than a single product.
Structure & chemistry
Molecular identity & reference confidence
Reference mass unavailable
Reference values are taken from the cited molecular record or curated profile. A database match is not independent laboratory verification; modifications, counter-ions, and formulations can change the measured mass.
- Molecular form
- 84-residue single-chain peptide; the N-terminal 1–34 fragment carries full receptor activity and is the basis of teriparatide
- Species
- Not established by this molecular identity audit
- Termini (N / C)
- Not specified / Not specified
Average reference mass
Reference policy updated: 2026-10-05
- Receptors
- PTH/PTHrP receptor type 1 (PTH1R), a class B G-protein-coupled receptor; signalling continues from endosomes after internalisation
- Backbone
- 84-residue single-chain peptide; the N-terminal 1–34 fragment carries full receptor activity and is the basis of teriparatide
- Status
- Endogenous hormone; recombinant human PTH(1-84) used as replacement therapy in hypoparathyroidism; N-terminal analogues approved for osteoporosis (see teriparatide, abaloparatide, palopegteriparatide) as of September 2026
Chemistry values: curated profile.
Clinical development snapshot
ClinicalTrials.gov lists 625 registered studies with “Parathyroid hormone” as an intervention (snapshot 2026-10-01). A registry footprint is not evidence of efficacy or approval.
| NCT | Title | Phase | Status | Updated |
|---|---|---|---|---|
| NCT07541209 | Safety and Efficacy of PTH-IA | Phase 2 | recruiting | 2026-10-01 |
| NCT07081997 | A Phase 3 Randomized Clinical Trial to Investigate the Safety and Efficacy of Palopegteriparatide at Doses Gre | Phase 3 | recruiting | 2026-09-30 |
| NCT07843901 | Lenvatinib in Patients With Advanced Parathyroid Carcinoma | Phase 2 | not yet recruiting | 2026-09-28 |
| NCT07836335 | Evaluation of the Role of Intraoperative Neuromonitoring(IONM) in Patients Undergoing Parathyroid Surgery for | Not applicable | completed | 2026-09-23 |
| NCT04339478 | Does Parathyroid Autofluorescence Reduces Unintensional Parathyroidectomy During Total Thyroidectomy With Cent | — | completed | 2026-09-23 |
| NCT07428057 | Postoperative Hypocalcemia After Thyroidectomy | — | recruiting | 2026-09-22 |
Change log
Dated observations from the data pipeline (registry flags, trial footprints, identifiers) and editorial reviews of this profile.
- Trials6 registered studies added on ClinicalTrials.gov (now 625).
- TrialsClinicalTrials.gov snapshot added: 619 registered studies, highest phase 4.
- EditorialProfile content reviewed and updated by the editorial team.
FAQ about Parathyroid hormone (PTH 1-84)
What is Parathyroid hormone (PTH 1-84)?+
Parathyroid hormone (PTH) is the 84-amino-acid peptide the parathyroid glands secrete to raise blood calcium: it enhances renal calcium reabsorption, increases active vitamin D production for intestinal absorption, and mobilises calcium from bone. Recombinant PTH(1-84) has been used as replacement therapy in hypoparathyroidism, and its N-terminal fragment is the basis of the osteoporosis drugs teriparatide and abaloparatide.
What Canadian product status is recorded for Parathyroid hormone (PTH 1-84)?+
Canadian product status for Parathyroid hormone (PTH 1-84) has not been verified in this profile. No verified record here does not mean no authorization exists. Status depends on the product, formulation and use; consult Health Canada's product records.
What is the typical length of Parathyroid hormone (PTH 1-84)?+
Parathyroid hormone (PTH 1-84) is commonly described as approximately 84 amino acids (Calcium-regulating peptide hormone).
What does parathyroid hormone do?+
It raises blood calcium by enhancing renal calcium reabsorption, increasing active vitamin D production for intestinal absorption, and mobilising calcium from bone. It is the body's main defence against low calcium.
How long is parathyroid hormone?+
84 amino acids. The first 34 residues carry full receptor activity and form the basis of teriparatide.
What is the difference between PTH and teriparatide?+
Teriparatide is the N-terminal 1–34 fragment of PTH made recombinantly and given as a daily pulse to build bone; PTH(1-84) is the full hormone, used as replacement in hypoparathyroidism.
Why does PTH build bone in some cases and break it down in others?+
Brief daily pulses stimulate bone formation; continuous exposure, as in hyperparathyroidism, mobilises calcium from bone. Differences in receptor signalling duration, including signalling from endosomes, are one proposed explanation.
What receptor does PTH use?+
The type 1 PTH/PTHrP receptor, a class B G-protein-coupled receptor that can keep signalling after it is internalised into the cell.
Related peptides
References & further reading
- 1.Goltzman (2018). Physiology of Parathyroid Hormone. Endocrinology and Metabolism Clinics of North America
- 2.Goltzman (2021). Pathophysiology of Hypercalcemia. Endocrinology and Metabolism Clinics of North America
- 3.Peña (2022). Endosomal parathyroid hormone receptor signaling. American Journal of Physiology — Cell Physiology
- 4.Shoback (2017). Does parathyroid hormone control bone quality? Endocrine
- 5.Drugs and Lactation Database (LactMed) (2023). Parathyroid Hormone
- 6.Madore et al. (2004). Parathyroid hormone. Journal of the American Academy of Orthopaedic Surgeons