PTH 1-34 ∞ Area

PTH 1-34

Meaning

PTH 1-34 refers to the biologically active N-terminal fragment of human parathyroid hormone, a polypeptide comprising the first 34 amino acids of the full-length 84-amino acid hormone. This specific sequence retains the primary physiological functions of the native hormone, particularly its crucial role in calcium and phosphate regulation.

Context

This peptide operates within the complex endocrine system, primarily impacting bone and kidney physiology to maintain mineral homeostasis. Its actions are central to the body’s adaptive responses to changes in circulating calcium levels, acting as a crucial signaling molecule in systemic mineral balance.

Significance

Clinically, PTH 1-34 is highly significant as a therapeutic agent for conditions characterized by bone loss, most notably severe osteoporosis. Its unique anabolic effect on bone, distinct from the catabolic actions of continuous native PTH, makes it a valuable intervention for improving bone mineral density and reducing fracture risk.

Mechanism

PTH 1-34 exerts its effects by binding to the parathyroid hormone receptor 1 (PTH1R) found on osteoblasts, osteocytes, and renal tubular cells. Intermittent administration of this peptide preferentially stimulates osteoblastic activity and bone formation, contrasting with the sustained elevation of endogenous PTH which promotes bone resorption.

Application

The synthetic form of PTH 1-34, known as teriparatide, is administered via daily subcutaneous injection for the treatment of postmenopausal women and men with high fracture risk due to osteoporosis, as well as glucocorticoid-induced osteoporosis. Its use follows specific treatment protocols, typically for a limited duration to maximize bone-building benefits.

Metric

The therapeutic efficacy of PTH 1-34 is monitored through regular assessments of bone mineral density, typically measured by dual-energy X-ray absorptiometry (DXA) scans. Additionally, serum markers of bone turnover, such as procollagen type I N-terminal propeptide (P1NP) and C-terminal telopeptide of type I collagen (CTX), provide insights into its anabolic actions.

Risk

Potential risks associated with PTH 1-34 therapy include transient hypercalcemia, especially after injection, and osteosarcoma, although the latter is a rare but serious concern that limits treatment duration. Contraindications involve pre-existing hypercalcemia, metabolic bone diseases other than osteoporosis, and a history of skeletal malignancies or radiation therapy.