parathyroid

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1. Adjacent to the thyroid gland,
2. Of, relating to, or obtained from the parathyroid glands.

1. Eithe rof the parathyroid glands.
2. A parathyroid hormone.

1. situated near the thyroid gland.
2. of, pertaining to, or produced by the parathyroid gland.
3. the parathyroid gland.

1. situated beside the thyroid gland.
2. one of the parathyroid glands.
3. a preparation containing parathyroid hormone from animal parathyroid glands; used for diagnosis and treatment of hypoparathyroidism.

• p. calcium-regulating hormone — see parathyroid hormone (below).
• p. cyst — remnants of the embryonic duct that connects the parathyroid and the thymus during embryogenesis. Called also Kursteiner's cyst.
• p. gland — small body in the region of the thyroid gland, occurring in a variable number of pairs, commonly two.
— The parathyroid contains two types of cell: chief cells and oxyphils. Chief cells are the major source of parathyroid hormone (PTH), the secretion of which is dependent on the serum calcium level. Through a closed-loop feedback mechanism a low serum calcium level stimulates secretion of PTH; conversely, a high serum calcium level inhibits its secretion. The essential role of PTH is maintenance of a normal serum calcium level in association with vitamin D and calcitonin.
• p. gland hyperplasia — may be focal and nodular or, more importantly diffuse. The latter occurs in cases suffering long-standing nutritional deficiency of calcium or renal insufficiency.
• p. hormone (PTH) — a simple, straight-chain polypeptide, synthesized in chief cells and stored in secretory granules. The hormone stimulates the formation and activity of resorptive osteocytes so that calcium is released into body fluids without extensive bone remodeling. This is its mineral homeostatic function and is a relatively quick, short duration response. It is also concerned in skeletal homeostasis by stimulating osteoclastic osteolysis, the slower acting process of bone remodeling.
• p. hormone-related protein, p. hormone-like peptide — associated with humoral hypercalcemia of malignancy (HHM); see pseudohyperparathyroidism.
• p. hyperfunction — see hyperparathyroidism, osteodystrophia fibrosa.
• p. secretory protein — stored in secretory granules with parathyroid hormone but has no known function. Called also chromogranin A.
• p. tumors — carcinomas occur rarely and adenomas more commonly, particularly in older dogs. Either type of tumor may be nonfunctional or functional, causing a primary hyperparathyroidism.