Serum levels of thyrotropin are decreased by oral calcium in healthy subjects but not in patients with primary hyperparathyroidism

• It has been suggested that calcium changes the set point of the pituitary thyroid feedback. It is not known, however, if small and slow changes of calcium and/or parathyroid hormone (PTH) within the physiological range influence the serum levels of thyrotropin (TSH) and thyroid hormones in healthy subjects or patients with primary hyperparathyroidism (pHPT). Nine healthy subjects and nine patients with pHPT were therefore investigated with an oral calcium load test. The patients were investigated before and 4 days after operation. During the test, serum levels of ionized calcium increased and serum levels of intact PTH decreased in both healthy subjects and patients pre- and postoperatively (p < 0.001). Furthermore, in patients, the suppressibility of serum levels of PTH by calcium increased postoperatively (p < 0.05). Serum levels of TSH decreased during the oral calcium load in healthy subjects (p < 0.01) but not in patients, whereas the serum levels of thyroid hormones did not change. It is concluded that oral calcium influences TSH secretion in healthy humans but not in patients with pHPT.

Subject headings

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Endokrinologi och diabetes (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Endocrinology and Diabetes (hsv//eng)

Keyword

Aged

Calcium

Case-Control Studies

Humans

Hyperparathyroidism

Middle Aged

Parathyroid Hormone

Pituitary Gland

Thyroid Hormones

Thyrotropin

Comparative Study

Journal Article

Research Support, Non-U.S. Gov't

Publication and Content Type

art (subject category)

ref (subject category)