Clinical experiences with human parathyroid hormone 1-34

Area of Science:

• Endocrinology
• Metabolic Disorders
• Pharmacology

Background:

• Parathyroid hormone (PTH) regulates calcium and phosphate homeostasis.
• Hypoparathyroidism involves deficient PTH production or action.
• Pseudohypoparathyroidism is characterized by PTH resistance.

Purpose of the Study:

• To evaluate the diagnostic utility of human PTH (1-34) in differentiating hypoparathyroidism subtypes.
• To assess the physiological responses to human PTH (1-34) infusion in normal subjects and patients.

Main Methods:

• Administration of human PTH (1-34) to nine normal subjects and ten hypoparathyroid patients.
• Measurement of plasma and urinary cyclic adenosine monophosphate (cAMP), urinary phosphate, urine calcium, and plasma prolactin levels.
• Analysis of cAMP response blunting to diagnose pseudohypoparathyroidism.

Main Results:

• In normal subjects, PTH (1-34) increased plasma cAMP, nephrogenous cAMP, urinary phosphate, and plasma prolactin, while decreasing urine calcium.
• Five patients with chronic hypocalcemia and hyperphosphatemia exhibited blunted cAMP responses to PTH (1-34).
• These five patients were diagnosed with pseudohypoparathyroidism, despite intact phosphaturic and hypocalciuric responses.

Conclusions:

• Human PTH (1-34) is a reliable diagnostic agent for identifying pseudohypoparathyroidism.
• The blunted cAMP response is a key indicator of PTH resistance.
• Human PTH (1-34) offers advantages over bovine PTH for diagnosing PTH resistance syndromes.