Hyperparathyroidism pathophysiology: Difference between revisions
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===Pathogenesis of primary hyperparathyroidism=== | ===Pathogenesis of primary hyperparathyroidism=== | ||
*Primary hyperparathyroidism is due to increase in secretion of parathyroid hormone from parathyroid gland. | |||
*Majority of times, increase in secretion of parathyroid hormone is the result of parathyroid adenoma. Other causes of increase in secretion of parathyroid hormone includes parathyroid hyperplasia and parathyroid carcinoma. | |||
*Calcium sensing receptor expression in reduced in parathyroid adenomas resulting in an increase in calcium sensing set point.<ref name="pmid8995751">{{cite journal| author=Gogusev J, Duchambon P, Hory B, Giovannini M, Goureau Y, Sarfati E et al.| title=Depressed expression of calcium receptor in parathyroid gland tissue of patients with hyperparathyroidism. | journal=Kidney Int | year= 1997 | volume= 51 | issue= 1 | pages= 328-36 | pmid=8995751 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=8995751 }} </ref><ref name="pmid8636374">{{cite journal| author=Kifor O, Moore FD, Wang P, Goldstein M, Vassilev P, Kifor I et al.| title=Reduced immunostaining for the extracellular Ca2+-sensing receptor in primary and uremic secondary hyperparathyroidism. | journal=J Clin Endocrinol Metab | year= 1996 | volume= 81 | issue= 4 | pages= 1598-606 | pmid=8636374 | doi=10.1210/jcem.81.4.8636374 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=8636374 }} </ref> | |||
*In parathyroid hyperplasia, an increase in cell number causes increased secretion of parathyroid hormone. | |||
*The exact pathogenesis of [disease name] is not fully understood. | *The exact pathogenesis of [disease name] is not fully understood. | ||
OR | OR | ||
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1];Associate Editor(s)-in-Chief:
Overview
- The exact pathogenesis of [disease name] is not fully understood.
OR
- It is thought that [disease name] is the result of / is mediated by / is produced by / is caused by either [hypothesis 1], [hypothesis 2], or [hypothesis 3].
- [Pathogen name] is usually transmitted via the [transmission route] route to the human host.
- Following transmission/ingestion, the [pathogen] uses the [entry site] to invade the [cell name] cell.
- [Disease or malignancy name] arises from [cell name]s, which are [cell type] cells that are normally involved in [function of cells].
- The progression to [disease name] usually involves the [molecular pathway].
- The pathophysiology of [disease/malignancy] depends on the histological subtype.
Pathohysiology
Parathyroid, Vitamin D, and mineral homeostasis
The effect of Parathyroid hormone on mineral metabolism is as follows:[1][2]
- Effect of parathyroid hormone on inorganic phosphate metabolism:
- Increases excretion of inorganic phosphate from kidney resulting in decreased serum concentration of phosphate.
- Effect on parathyroid hormone on calcium metabolism:
- Direct effect:
- Increased resorption of bones.
- Decreases excretion from kidney.
- Indirect effect:
- Increases conversion of inactive 25-hydroyxvitamin D to the active 1,25-dihydroyxvitamin D which increases absorption of calcium from gut.Decreased phosphate concentration also increases this conversion process. Vitamin D also synergizes with parathyroid action on bone.
- Decreased serum inorganic phosphate concentration prevents precipitation of calcium phosphate in bones.
- Both these direct and indirect mechanism results in an increased serum calcium concentration.
- Direct effect:
- Effect of parathyroid hormone on magnesium concentration:
- Decreases excretion of magnesium resulting in increased serum magnesium concentretion.
Effect of minerals and vitamin D on parathyroid hormone:
- Decrease in serum calcium concentration stimulates parathyroid hormone.
- Calcium provides negative feedback on parathyroid hormone.
- Magnesium provides negative feedback on parathyroid hormone.
- Vitamin D decreases the concentration of parathyroid hormone.
The sequence of events is shown in the algorithm below:
| Parathyroid hormone | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Kidney | Bone | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Decreased excretion of magnesium | Increasead conversion of inactive 25-hydroyxvitamin D to the active 1,25-dihydroyxvitamin D | Increase excretion of inorganic phosphate | Decrease excretion of calcium | Increased resorption of bone | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Increased serum concentration of magnesium | Increased absorption of calcium from gut | Decreased serum concentration of inorganic phosphate | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Prevents precipitation of calcium phosphate in bones | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Increased serum concentration of calcium | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Calcium-sensing receptors
- Calcium -ensing receptors are present on parathyroid glands. They are a type of 7-transmembrane receptors in G-protein coupled receptors superfamily of receptors.[3]
- Calcium-sensing receptors sense change in extracellular concentration of inonised calcium.[4]
- Calcium-sensing receptor expression in reduced in primary hyperparathyroidism (parathyroid adenomas) and secondary hyperparathyroidism.[5]
- This reduced expression of receptor causes an increases in calcium sensing set point.[6]
- This in turn leads to increase in secretion of parathyroid hormone in presence on normal serum concentration of extracellular ionized calcium.
Pathogenesis of primary hyperparathyroidism
- Primary hyperparathyroidism is due to increase in secretion of parathyroid hormone from parathyroid gland.
- Majority of times, increase in secretion of parathyroid hormone is the result of parathyroid adenoma. Other causes of increase in secretion of parathyroid hormone includes parathyroid hyperplasia and parathyroid carcinoma.
- Calcium sensing receptor expression in reduced in parathyroid adenomas resulting in an increase in calcium sensing set point.[5][6]
- In parathyroid hyperplasia, an increase in cell number causes increased secretion of parathyroid hormone.
- The exact pathogenesis of [disease name] is not fully understood.
OR
- It is thought that [disease name] is the result of / is mediated by / is produced by / is caused by either [hypothesis 1], [hypothesis 2], or [hypothesis 3].
- [Pathogen name] is usually transmitted via the [transmission route] route to the human host.
- Following transmission/ingestion, the [pathogen] uses the [entry site] to invade the [cell name] cell.
- [Disease or malignancy name] arises from [cell name]s, which are [cell type] cells that are normally involved in [function of cells].
- The progression to [disease name] usually involves the [molecular pathway].
- The pathophysiology of [disease/malignancy] depends on the histological subtype.
Genetics
- [Disease name] is transmitted in [mode of genetic transmission] pattern.
- Genes involved in the pathogenesis of [disease name] include [gene1], [gene2], and [gene3].
- The development of [disease name] is the result of multiple genetic mutations.
Associated Conditions
Gross Pathology
- On gross pathology, [feature1], [feature2], and [feature3] are characteristic findings of [disease name].
Microscopic Pathology
- On microscopic histopathological analysis, [feature1], [feature2], and [feature3] are characteristic findings of [disease name].
References
- ↑ HARRISON MT (1964). "INTERRELATIONSHIPS OF VITAMIN D AND PARATHYROID HORMONE IN CALCIUM HOMEOSTASIS". Postgrad Med J. 40: 497–505. PMC 2482768. PMID 14184232.
- ↑ Nussey, Stephen (2001). Endocrinology : an integrated approach. Oxford, UK Bethesda, Md: Bios NCBI. ISBN 1-85996-252-1.
- ↑ Brown EM, Gamba G, Riccardi D, Lombardi M, Butters R, Kifor O; et al. (1993). "Cloning and characterization of an extracellular Ca(2+)-sensing receptor from bovine parathyroid". Nature. 366 (6455): 575–80. doi:10.1038/366575a0. PMID 8255296.
- ↑ Brown EM, Pollak M, Seidman CE, Seidman JG, Chou YH, Riccardi D; et al. (1995). "Calcium-ion-sensing cell-surface receptors". N Engl J Med. 333 (4): 234–40. doi:10.1056/NEJM199507273330407. PMID 7791841.
- ↑ 5.0 5.1 Gogusev J, Duchambon P, Hory B, Giovannini M, Goureau Y, Sarfati E; et al. (1997). "Depressed expression of calcium receptor in parathyroid gland tissue of patients with hyperparathyroidism". Kidney Int. 51 (1): 328–36. PMID 8995751.
- ↑ 6.0 6.1 Kifor O, Moore FD, Wang P, Goldstein M, Vassilev P, Kifor I; et al. (1996). "Reduced immunostaining for the extracellular Ca2+-sensing receptor in primary and uremic secondary hyperparathyroidism". J Clin Endocrinol Metab. 81 (4): 1598–606. doi:10.1210/jcem.81.4.8636374. PMID 8636374.