甲状旁腺(英文版)

PTH and Parathyroid Glands
Calcitonin: Biologic Effects
CT is of clinical interest for two reasons
1. CT is important as a tumor marker in medullary thyroid carcinoma (MCT).
Hyperparathyroidism
Parathyroid Cancer
Hypoparathyroidism
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Parathyroid gland
CONTENTS
Calcium and Bone Metabolism
Calcium-Regulating Hormones Regulation of Parathyroid Hormone Secretion Parathyroid Disease
Vocabulary
Vitamin D and Its Metabolites
Regulation of Parathyroid Hormone Secretion
Regulation of parathyroid hormone secretion by Ca2+
The extracellular calcium-sensing receptor (CaSR), expressed on the parathyroid cell senses changes in extracellular calcium—so, ↓ Ca2+ →↑ PTH secretion, while ↑ levels of Ca2+ →↓ PTH secretion.
PTH: Biologic Effects
PTH ↑ both bone formation and bone resorption; with regard to calcium homeostasis, the effect of PTH on bone resorption is dominant
PTH: Biologic Effects
the effect of PTH on intestinal calcium absorption is indirect, resulting from ↑ renal production of the intestinally active vitamin D metabolite, 1,25(OH)2D3
• Adjusted Ca = measured Ca + 0.02 × (40 − albumin)
(where calcium is in mmol/L and albumin in g/L).
Calcium-Regulating Hormones
The parathyroid gland
PTH: Biologic Effects
04
Stimulus secretion coupling (e.g., chromaffin cells)
Calcium inized
Complexed to citrate, phosphate
Bound to protein
biologically active (50%)
calcium /ˈkælsiəm/ phosphorus /ˈfɒsfərəs/ skeletal /ˈskelətl/ citrate /'sɪtreɪt/ proximal /ˈprɒksɪməl/ bicarbonate/ˌbaɪˈkɑːbənət/ transcription /trænˈskrɪpʃn/
biologically active (5%)
inactive (45%)
Calcium in the Circulation
• In most clinical situations, direct measurement of ionized calcium concentration is unnecessary. However, it is important to adjust the measured calcium concentration for the prevailing serum albumin concentration:
钙 磷 骨骼的 枸橼酸盐 近端的 碳酸氢盐 转录
Vocabulary
hydroxylase /hai'drɔksileis/ resorption /ri'sɔ:pʃən/ osteoclast /'ɒstɪəʊklæst/ inhibitor /ɪnˈhɪbɪtər/ hypercalcemia/,haipə,kæl'si:miə/ osteoporosis /ˌɒstiəʊpəˈrəʊsɪs/
Regulation of parathyroid hormone secretion
• Besides calcium, there are other several regulators of PTH secretion. Hypermagnesemia inhibits PTH, while conversely, moderate hypomagnesemia can stimulate PTH secretion, even though prolonged depletion of magnesium will paralyze it.
On kidney—PTH has direct effects: ↑ Ca2+ reabsorption in the distal convoluted tubes, ↓ reabsorption of phosphate in the renal proximal tubule and of bicarbonate
• Transcription of the PTH gene is also regulated by vitamin D: ↑ levels of 1,25(OH)2D inhibits PTH gene transcription.
Parathyroid Disease
Parathyroid Disease
Abbreviation
➢ PTH (Parathyroid hormone) 甲状旁腺素 ➢ CT (Calcitonin) 降钙素 ➢ MCT (medullary thyroid carcinoma) 甲状腺髓样癌 ➢ UVB (ultraviolet b) 中波紫外线 ➢ CaSR (calcium sensing receptor) 钙敏感受体
羟化酶 重吸收 破骨细胞 抑制剂 高钙血症 骨质疏松症
Vocabulary
controversy /ˈkɒntrəvɜːsi/
有争议
complication /ˌkɒmplɪˈkeɪʃn/
并发症
rickets /ˈrɪkɪts/
佝偻病
osteomalacia /,ɒstɪəʊmə'leɪʃɪə/ 软骨病
mineralization /,mɪnərəlaɪ'zeɪʃən/ 矿化作用
cholecalciferol /,kaulikæl'sifərɔl/ 胆钙化醇
Phrase
chromaffin cells intestinal mucosa distal convoluted tubes
嗜铬细胞 肠粘膜 远曲小管
Calcium and Bone Metabolism
Roles of Calcium
01
Building block of bone, and helps maintain bone strength
02 Skeletal strength
03 Neuromuscular conduction
2. CT has therapeutic uses as an inhibitor of osteoclastic bone resorption and it can be used in the treatment of Paget disease, hypercalcemia, and osteoporosis.