parathyroid glands

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Related to parathyroid glands: Adrenal glands, parathyroid hormone, pancreas, hyperparathyroidism

parathyroid

[par″ah-thi´roid]

3. a preparation containing parathyroid hormone from animal parathyroid glands; used for diagnosis and treatment of hypoparathyroidism.

parathyroid glands four small endocrine bodies in the region of the thyroid gland; they contain two types of cells: 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. It does this by exerting its effects on bone, kidney, and gastrointestinal tract. In bone, it enhances bone resorption by increasing digestion of the bone matrix by osteoclasts, which produces calcium that gets released into the bloodstream. In the kidney, PTH increases the excretion of phosphate and the reabsorption of filtered calcium. In the intestine, it increases intestinal absorption of calcium. The parathyroid glands may be subject to either hyperparathyroidism or hypoparathyroidism.

parathyroid glands

Four, yellow, bean-shaped bodies, each about 0.5 cm long, lying behind the THYROID GLAND, usually embedded in its capsule. The parathyroids secrete a hormone, parathyroid hormone (parathormone or PTH), into the blood if the level of calcium in the blood drops. This hormone promotes the release of calcium from the bones, controls loss in the urine and increases absorption from the intestine, thus correcting the deficiency in the blood. Maintenance of accurate levels of blood calcium is more important, physiologically, than the strength of the bones. Secretion of abnormal quantities of PTH from a parathyroid tumour can lead to bone softening. Underaction of the parathyroids causes a dangerous drop in the blood calcium.

Sandström,

Ivor V., swedish anatomist, 1852-1889.

Sandström bodies - Synonym(s): parathyroid glands

parathyroid glands

small clumps of endocrine tissue (usually four) on the back of the thyroid gland which secrete parathyroid homone (PTH). This acts to increase calcium ion concentration in the extracellular fluid, counterbalanced by calcitonin from the thyroid gland which has the opposite effects. Together they correct any changes in blood [Ca²⁺] by action on absorption of calcium from the gut, its deposition in bone and its excretion by the kidneys. See also hormones; Table 1.

**Table 1:** Hormones
Site of production	Name of hormone	Main targets	Involved in regulating:	Secretion controlled by:
Hypothalamus	Releasing and inhibiting hormones	Anterior pituitary (via local blood vessels)	Secretion of anterior pituitary hormones	Other brain regions; feedback re regulated hormones and their actions
	Neurohormones released from posterior pituitary:
	Oxytocin	Uterus, breasts	Labour and lactation	Afferent information from target organs
	Antidiuretic hormone (ADH, vasopressin)	Kidneys	Water loss: ECF volume and osmolality	Hypothalamic osmoreceptors
Anterior pituitary	(Human) growth hormone (H)GH	Most cells	Growth and metabolism	Hypothalamic releasing and inhibiting hormones via local blood vessels
	Prolactin	Breasts	Milk production
	Trophic hormones:
	Thyroid-stimulating (TSH)	Thyroid gland	Thyroid secretions
	Gonadotrophins	Ovary or testis	Germ cell maturation and hormone secretions
	Adrenocorticotrophic (ACTH)	Adrenal cortex	Cortisol secretion
Pineal body	Melatonin	Widespread, including brain, thymus, etc.	Sleep/wake cycle Antioxidant Immune system	Hypothalamus; varying light input from retina
Thyroid	Thyroxine Triiodothyronine Calcitonin	Most cells Bone, kidneys, gut	Cellular oxidative metabolism Decreases ECF [Ca²⁺]	TSH from anterior pituitary. Negative feedback from blood hormone concentration ECF [Ca²⁺]
Parathyroids	Parathormone	Bone, kidneys, gut	Calcium and phosphorus absorption, secretion and turnover in bone. Increases ECF [Ca²⁺]	ECF [Ca²⁺]
Adrenal: Cortex	Cortisol Aldosterone Androgens	Most cells Kidneys Gonads & other tissues	Metabolism Response to stress Na and K balance Sex characteristics and reproductive function	ACTH from anterior pituitary ECF [Na⁺] [K⁺] Renin-angiotensin ACTH
Medulla	Adrenaline Noradrenaline	Heart, smooth muscle, glands	Cardiovascular and metabolic adjustments to activity and stress	Sympathetic nervous system
Atrial wall	Atrial natriuretic hormone	Kidneys	Blood volume; increases sodium (therefore also water) loss in urine	Stretch of atrial wall by venous pressure
Gonads: Testis	Androgens (mainly testosterone)	Genitalia and other tissues	Reproductive function and sex characteristics	Anterior pituitary gonadotrophins
Ovary	Oestrogens Progesterone	Uterus, breasts and other tissues	Menstrual cycle, pregnancy, lactation
Pancreas	Insulin, glucagon Somatostatin	Most cells Other secretory cells in the pancreas	Blood levels, storage and cellular uptake of nutrients, notably glucose, but also proteins and fats	Blood levels of nutrients; autonomic nervous system; other gastrointesinal hormones
Alimentary tract
Stomach	Gastrin	Gastric acid-secreting cells	Gastrointestinal functions: motility, digestive juices and other secretions	Local chemical and mechanical factors in the alimentary tract
Small intestine	Secretin Cholecystokinin- pancreozymin (CCK-PZ) Somatostatin, motilin Other peptide hormones including vasoactive intestinal peptide (VIP)	Widespread on GI tract	Several GI functions including bile flow, pancreatic enzyme and exocrine secretions	Ingestion of food, distension of GI tract

References in periodicals archive ?

Parathyroid glands of at least 1 cm display vascularity by colour Doppler or power Doppler characterised by low resistance waveforms on spectral analysis.

Ultrasound--first imaging modality in the detection of parathyroid adenomas

Although inexpensive and readily available, monitoring the intraoperative ionized Ca and total Ca is not clinically reliable for confirming removal of hyperfunctioning parathyroid glands.

The parathyroid glands, primary and secondary hyperparathroidism and assays for parathyroid hormone

Superior parathyroid glands tend to be found dorsal to the mid-to-superior thyroid pole and in the retropharyngeal space (Figure 2).

Parathyroid scintigraphy: optimizing preoperative localization

Meanwhile, nuclear imaging has helped doctors pinpoint which parathyroid gland is diseased, reducing the need for exploratory surgery.

Parathyroid surgery proves its worth

The first is primary hyperparathyroidism, which is the result of the hypersecretion of PTH by abnormal parathyroid glands, is relatively common, with an overall incidence of approximately 1 in 1,000.

Point-of-care testing of parathyroid hormone during the surgical treatment of hyperparathyroidism

In FMEN1, all four parathyroid glands tend to be overactive.

Familial Multiple Endocrine Neoplasia Type 1

Your doctor can do a blood test to find out if your parathyroid glands are too active.

Bone disease in chronic kidney failure

Primary hyperparathyroidism (PHPT) occurs as a result of unregulated over-production of parathyroid hormone (PTH) secreted from the parathyroid glands, leading to an inappropriate calcium homeostasis.

The many guises of primary hyperparathyroidism... An unchanged scenario

Hypoparathyroidism, designated an orphan disease by the European Commission (EC), is a rare disease that occurs when inadequate levels of PTH are secreted by the parathyroid glands.

CHMP recommends EU conditional marketing authorisation for Natpar

Application of carbon nanoparticles suspensions injection can stain the lymph nodes of the center compartment while leaving the parathyroid glands unstained (because of the negative development of parathyroid glands to carbon nanoparticles, Chongqing Lummy Pharmaceuticals, China), thus helping to identify and protect parathyroid glands and the RLN [Figure 3] and [Figure 4], as well as facilitating the identification and clearance of lymph nodes.

Comparative Study between Robotic Total Thyroidectomy with Central Lymph Node Dissection via Bilateral Axillo-breast Approach and Conventional Open Procedure for Papillary Thyroid Microcarcinoma

The left recurrent laryngeal nerve and the parathyroid glands were identified, and dissection was extended through the ligament of Berry across the front face of the trachea and partway down the right side.

An extended toboggan technique for resection of substernal thyroid goiters

The cause of hypoparathyroidism in thalassemia is assumed to be iron deposition in parathyroid glands, but the reason why some patients develop hypoparathyroidism and others do not is not exactly known.