Influence of vitamin D on parathyroid function in the elderly

Area of Science:

• Endocrinology
• Gerontology
• Mineral Metabolism

Background:

• Age-related changes in mineral metabolism are complex.
• Vitamin D status and parathyroid hormone (PTH) function are critical for calcium homeostasis.
• Understanding these changes in healthy aging is important for clinical practice.

Purpose of the Study:

• To investigate the effects of age and vitamin D status on parathyroid function in healthy adults.
• To assess changes in serum calcium, phosphorus, vitamin D metabolites, and PTH with aging.
• To evaluate the PTH response to calcium infusion and vitamin D treatment in the elderly.

Main Methods:

• Studied 129 healthy subjects aged 20-89 years in Cordoba, Spain.
• Measured serum calcium, phosphorus, 25-hydroxyvitamin D (25OHD), 1,25-dihydroxyvitamin D [1,25-(OH)2D], alkaline phosphatase, and PTH (carboxyl-terminal and intact).
• Administered calcium infusion and vitamin D treatment to assess PTH suppressibility and setpoint.

Main Results:

• Serum calcium, phosphorus, 25OHD, and 1,25-(OH)2D decreased with age, while alkaline phosphatase increased.
• Intact PTH [PTH(1-84)] increased significantly with age (+30% in those >80 years).
• PTH(1-84) correlated negatively with serum calcium, 25OHD, and IGF-I; 1,25-(OH)2D correlated with 25OHD, PTH, and IGF-I.
• Elderly subjects showed a blunted PTH nadir after calcium infusion, but the relative decrease was similar to younger adults when corrected for calcium changes.
• Vitamin D treatment reduced the basal calcium-PTH setpoint in elderly subjects.

Conclusions:

• Healthy elderly individuals exhibit a modest increase in intact PTH, remaining within normal ranges.
• Parathyroid hormone secretion remains normally suppressible by acute calcium infusion in the elderly.
• Vitamin D treatment can effectively lower the basal calcium-PTH setpoint in older adults.