Parathyroid Hormone
Also known as: Natpara, Natpar, rhPTH(1-84), Recombinant human parathyroid hormone, PTH 1-84
Key Facts: Parathyroid Hormone
- Category
- Hormonal
- FDA Status
- FDA Approved
- Clinical Status
- FDA Approved (January 2015) but discontinued globally - Takeda ended manufacturing at the end of 2024, the US Special Use Program closed 31 December 2025, and Natpar is listed as discontinued by the EMA. Carried a boxed warning for osteosarcoma and a REMS. WADA: not on the 2026 Prohibited List.
- Banned in Sport (WADA)
- Not on the WADA Prohibited List (2026).
- Administration
- Subcutaneous injection once daily in the thigh, alternating thighs
- Typical Dose
- 50 mcg once daily (historical label)
- Frequency
- Once daily
- Duration
- Long-term hormone replacement (before discontinuation)
How does Parathyroid Hormone work?
PTH(1-84) is the body's main calcium-raising hormone. It binds the PTH1 receptor in kidney and bone, increasing calcium reabsorption in the kidney, boosting activation of vitamin D (which raises calcium absorption from the gut), and releasing calcium from bone. In hypoparathyroidism, replacing it lets patients lower the heavy calcium and active vitamin D doses that can damage the kidneys over time. The weak spot was pharmacokinetics: the label reports an apparent half-life of about 3 hours, so a single daily shot gave a peak and trough rather than steady levels. That is the problem the newer long-acting prodrug was designed to fix.
What does the research show?
Approval rested on REPLACE (Mannstadt and colleagues, Lancet Diabetes and Endocrinology, 2013), a double-blind phase 3 trial that randomized 134 adults 2:1 to rhPTH(1-84) 50 mcg daily (titratable to 75 or 100 mcg) or placebo for 24 weeks. 53% on drug achieved at least a 50% cut in oral calcium and active vitamin D with stable serum calcium, vs 2% on placebo; 43% stopped active vitamin D entirely vs 5%. Hypercalcemia was more common on drug (19% vs 3%). Like other PTH drugs it carried a boxed warning about osteosarcoma seen in rats and was only available through a REMS program. Then manufacturing fell apart: rubber particles in the cartridge led to a US recall in 2019, an FDA complete response letter followed, and in October 2022 Takeda said it could not fix the problem and would stop production at the end of 2024. The US Special Use Program closed on 31 December 2025, and the EMA's shortage page now lists Natpar as discontinued. It remains a useful reference point in hypoparathyroidism research, but it is not a current treatment option.
FDA Approval Studies
This peptide is FDA approved. Below are the key clinical trials that supported its approval.
REPLACE
NPS Pharmaceuticals • Phase 3
134
24 weeks
At least 50% reduction in oral calcium and active vitamin D with serum calcium maintained
- ✓53% responders vs 2% placebo
- ✓43% stopped active vitamin D vs 5%
- ✓Adverse event rates broadly similar to placebo
What doses have been studied?
Typical Dosingⓘ
Community experience
50 mcg once daily (historical label)
25-100 mcg once daily
Once daily
These are the historical labeled doses. The product is no longer manufactured or distributed, so there is no current dosing in practice. People who were on it have generally been switched to other therapy by their endocrinologist.
Research Dosingⓘ
Scientific studies
Historical FDA-approved labeled dosing (product discontinued)
Doses from Studies
50 mcg once daily, titrated in 25 mcg steps to max 100 mcg
FDA Approved Labeling - Natpara prescribing information, section 2 ↗
50 mcg daily, titratable to 75 or 100 mcg
Phase 3 RCT - Mannstadt et al. 2013, REPLACE, Lancet Diabetes Endocrinol ↗
Duration
Long-term hormone replacement (before discontinuation)
Administration
Subcutaneous injection once daily in the thigh, alternating thighs
When and how is Parathyroid Hormone taken?
Best Time to Take
Same time each day (historical label)
Once daily in the thigh
Food Recommendation
With or without food
Why This Timing?
With a half-life of about 3 hours, consistent daily timing kept calcium levels more predictable. The label did not tie dosing to meals.
What are the side effects of Parathyroid Hormone?
Not everyone experiences these effects. Individual responses vary based on dosage, duration, and personal factors.
- ●Paresthesia (tingling)
- ●Hypocalcemia, especially when doses are missed or stopped
- ●Hypercalcemia (19% vs 3% placebo)
- ●Headache
- ●Nausea, vomiting, diarrhea
- ●Joint pain
- ●Hypercalciuria
- ●Boxed warning: osteosarcoma in rats; avoided in people at higher risk
- ●Digoxin toxicity risk if calcium rises
References
- https://scholar.harvard.edu/sites/scholar.harvard.edu/files/mannstadt/files/mannstadt_replace_tlde_2013.pdf
- https://www.rxlist.com/natpara-drug.htm
- https://www.pharmamanufacturing.com/industry-news/news/21435947/takeda-to-stop-manufacturing-rare-disease-hormone-drug
- https://www.ema.europa.eu/fr/medicines/human/shortages/natpar
Research This Peptide Further
Frequently Asked Questions
What does Parathyroid Hormone do?
Parathyroid hormone here means rhPTH(1-84), a recombinant copy of the full 84-amino-acid hormone, sold as Natpara (Natpar in Europe). It was FDA approved in January 2015 as an add-on to calcium and vitamin D for hypoparathyroidism. It is effectively gone now: a rubber particle problem led to a 2019 US recall, Takeda stopped making it at the end of 2024, the US special use program closed at the end of 2025, and the EMA lists it as discontinued. Patients have largely moved to palopegteriparatide (Yorvipath).
How does Parathyroid Hormone work?
PTH(1-84) is the body's main calcium-raising hormone. It binds the PTH1 receptor in kidney and bone, increasing calcium reabsorption in the kidney, boosting activation of vitamin D (which raises calcium absorption from the gut), and releasing calcium from bone. In hypoparathyroidism, replacing it lets patients lower the heavy calcium and active vitamin D doses that can damage the kidneys over time. The weak spot was pharmacokinetics: the label reports an apparent half-life of about 3 hours, so a single daily shot gave a peak and trough rather than steady levels. That is the problem the newer long-acting prodrug was designed to fix.
Is Parathyroid Hormone FDA approved?
Yes, Parathyroid Hormone is FDA approved. FDA Approved (January 2015) but discontinued globally - Takeda ended manufacturing at the end of 2024, the US Special Use Program closed 31 December 2025, and Natpar is listed as discontinued by the EMA. Carried a boxed warning for osteosarcoma and a REMS. WADA: not on the 2026 Prohibited List.
Is Parathyroid Hormone banned in sport?
Not on the WADA Prohibited List (2026).
What are the side effects of Parathyroid Hormone?
Reported side effects include: Paresthesia (tingling), Hypocalcemia, especially when doses are missed or stopped, Hypercalcemia (19% vs 3% placebo), Headache, Nausea, vomiting, diarrhea. Individual responses vary based on dosage, duration, and personal health factors.
What is the typical dose of Parathyroid Hormone?
Community-reported common dose: 50 mcg once daily (historical label) (Once daily). Range: 25-100 mcg once daily. Administration: Subcutaneous injection once daily in the thigh, alternating thighs. Prescription drug. Dose set by prescriber per label. Not medical advice.
Related Peptides
Peptides commonly compared with Parathyroid Hormone or used in similar applications.
HCG (Human Chorionic Gonadotropin)
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HormonalOxytocin
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HormonalLeuprolide
FDALeuprolide (brand name Lupron) is a synthetic GnRH agonist, a modified peptide far more potent than natural GnRH, and it is FDA-approved for advanced prostate cancer, endometriosis, uterine fibroids, and central precocious puberty. The clever part is counterintuitive: it works by overstimulating the GnRH system so hard that the pituitary shuts down sex hormone production. It is a real, long-established prescription drug (first US approval 1985), not a research peptide, and it carries meaningful side effects from the low-hormone state it creates.
HormonalDesmopressin
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HormonalOctreotide
FDAOctreotide is a synthetic eight-amino-acid mimic of the natural hormone somatostatin, the body's main 'off switch' for hormone secretion. It shuts down excess growth hormone, so it is a frontline FDA-approved drug for acromegaly, and it also tames the flushing and diarrhea of hormone-secreting carcinoid and other neuroendocrine tumors. This is real, approved medicine with decades of clinical data behind it, sold as Sandostatin (injectable, since 1988), Sandostatin LAR (monthly depot), and Mycapssa (oral capsule, approved 2020).
HormonalLanreotide
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