Parathyroid Hormone (rhPTH 1-84)
Also known as: Natpara, Natpar, rhPTH(1-84), Parathyroid hormone
Recombinant full-length human PTH, FDA-approved in 2015 as Natpara for hypoparathyroidism. Manufacturing was discontinued at the end of 2024.
Last updated
Mechanism of Action
Recombinant human parathyroid hormone (1-84) is identical to the 84-amino-acid hormone made by the parathyroid glands. Acting on PTH1R in kidney and bone, it increases renal calcium reabsorption, promotes activation of vitamin D (1,25-dihydroxyvitamin D) to raise intestinal calcium absorption, and increases phosphate excretion. In hypoparathyroidism this replaces the missing hormone and reduces the need for high-dose calcium and active vitamin D.
- Half-life
- ~3 hours (subcutaneous)
- Administration Routes
- Subcutaneous
- Research Status
- Clinical
Reported Benefits
- Maintained serum calcium while reducing oral calcium and active vitamin D needs (REPLACE trial)
- Lowers urinary calcium and serum phosphate in hypoparathyroidism
- Long-term data on bone and biochemical effects over years of use
Potential Side Effects
- Boxed warning: osteosarcoma seen in rat studies
- Hypocalcemia and hypercalcemia, especially when doses change or stop
- Paresthesia, headache, nausea and muscle cramps
- Diarrhea and joint pain
Common Dosing
Labeled dosing started at 50 mcg injected subcutaneously into the thigh once daily, adjusted in steps while monitoring serum calcium, with calcium and active vitamin D tapered accordingly. Because manufacturing ended in 2024, new patients are generally not started on it. Dosing is set and supervised by the prescribing clinician.
The dosing information above is aggregated from research literature and anecdotal community reports for educational purposes only. It is not a recommendation, prescription, or medical advice. Peptides are sold as research chemicals only and are not intended for human use.
Contraindications
- Increased osteosarcoma risk (Paget's disease, open epiphyses, prior skeletal radiation, unexplained alkaline phosphatase elevation)
- Hypoparathyroidism caused by calcium-sensing receptor activating mutations (not studied)
- Acute post-surgical hypoparathyroidism (not studied)
No documented stacking partners for Parathyroid Hormone (rhPTH 1-84) yet.
- View
Efficacy and safety of recombinant human parathyroid hormone (1-84) in hypoparathyroidism (REPLACE): a double-blind, placebo-controlled, randomised, phase 3 study
2013
- View
The Clinical and Skeletal Effects of Long-Term Therapy of Hypoparathyroidism With rhPTH(1-84)
2023
- View
Open-label extension of a randomized trial investigating safety and efficacy of rhPTH(1-84) in hypoparathyroidism
2024