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Role of parathormone, calcitonin and vitamin D in the Calcium homeostasis.pptx
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- 2. Synopsis o Calcium andPhosphate oParathormone oCalcitonin oVitamin D
- 3. Introduction Calcium – Imminentin all the activities of the cell, tissues and organs Phosphate – Inevitable role in the human body
- 4. Normal levels Normal Calciumlevel- 9 to 11 mg/dl Normal phosphate level-2.5 to 4.5 mg/dl
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- 9. Homeostasis Homeostasis of calciumand phosphate are maintained by the hormones: Parathormone Calcitonin & Vitamin D
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- 11. Parathormone 1. Source 2. Natureof hormone 3. Steps of Synthesis 4. Normal plasma concentration 5. Metabolism 6. Mechanism of action(Second messenger) 7. Physiological actions 8. Factors regulating secretion 9. Applied physiology
- 12. 1.Source oFour Parathyroid glands oAt fourpoles of thyroid gland posteriorly
- 13. Two types ofcells Predominant type Secrete Parathormone(PTH) Chief cells Oxyphil cells Oxyphil granules Appear during puberty Do not secrete PTH
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- 15. 2.Nature of hormone Polypeptide of84 Aminoacid
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- 17. 3.Synthesis o N terminal- involvedin calcium regulation o C terminal- not involved in calcium regulation
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- 19. 5.Metabolism oHalf life: 10minutes oMetabolized in the Liver and oCleared by the kidneys
- 20. 6.Mechanism of action oType 1 Receptor o Type 2 Receptor o Type 3 Receptor PTH1 R PTH2 R CPTH PTH and PTHrP PTH only Carboxy- terminal only
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- 23. Kidney Increased Calcium reabsorption Increased Calcium reabsorption PTH Decreasedphosphate reabsorption Through vitamin D PTH PTH Phosphaturia
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- 25. Bone Increased bone resorption Increased calcium Increasedphosphate Increased hydroxyproline Increased hydroxylysine PTH
- 26. An indexof osteoclastic activity Increased hydroxyproline in urine
- 27. Osteocytic osteolysis Receptor activatorof nuclear factor-κB ligand (RANKL) PTH
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- 29. 8. Regulation ofsecretion Plasma calcium Vitamin D
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- 37. oChronic renal disease oRickets oMalignancies(Bone metastasis) o CA Breast,Lungs( ectopic PTHrP) Secondary Hyperparathyroidism Hypercalcemia
- 38. Pseudo Hypoparathyroidism Congenital variety Symptomsof PTH deficiency are observed in presence of normal PTH in plasma Receptor defect- no increase in cAMP and IP3 Hypocalcemia Increased bone density
- 39. Tetany During thyroidectomy- accidentalremoval of parathyroid gland occurs – leads to acute hypocalcemia (Tetany) which develops 24-48 hours postoperatively
- 40. Features of Tetany Chvostek’ssign Quick contraction of facial muscles of same side by tapping over the facial nerve at the angle of the jaw
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- 44. Treatment of Tetany Administrationof ionized calcium and Parathormone
- 45. To summarize.. 1. Source 2.Nature of hormone 3. Steps of Synthesis 4. Normal plasma concentration 5. Metabolism 6. Mechanism of action(Second messenger) 7. Physiological actions 8. Factors regulating secretion 9. Applied physiology
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- 47. Calcitonin 1. Source 2. Natureof hormone 3. Steps of Synthesis 4. Normal plasma concentration 5. Metabolism 6. Mechanism of action(Second messenger) 7. Physiological actions 8. Factors regulating secretion 9. Applied physiology
- 48. 1.Source Parafollicular cells ofthyroid gland secrete Calcitonin
- 49. 2.Nature of hormone Polypeptide of32 aminoacids
- 50. 3.Synthesis Major stimulus isrise in calcium level Above 9 mg% of plasma calcium, secretion of calcitonin is directly proportional to the calcium concentration
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- 52. 5.Metabolism Half life: 5-10minutes Metabolized in the Liver
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- 54. 7.Physiological actions Actson bone Acts on kidney
- 55. Effect on bone 1.Decreasesplasma calcium level 2.Decreases plasma phosphate level
- 56. Effect on Kidney Decreases calcium and also phosphate reabsorption by kidney Calciuria and phosphaturia occurs
- 57.
- 58. 7.Regulation of secretion Dopamine Cholecystokinin Gastrin Secretin Estrogen
- 59. Zollinger Ellison syndrome Gastrinincreases Calcitonin level
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- 62. Calcitonin escape Injection of calcitonin HypocalcemiaBy inhibiting Bone resorption Antiresorptive action begins to wane within hours Body escapes the hypocalcemic effects of calcitonin
- 63. Calcitonin escape Probably dueto downregulation of calcium receptors Limits the use of calcitonin in long term management of hypercalcemia
- 64. Calcitonin escape- Significance Bones normalin medullary carcinoma of thyroid Protects against postprandial hypercalcemia During pregnancy and lactation, calcitonin protects bone mass by opposing osteoclastic activity.
- 65. Clinical uses ofcalcitonin Paget’s disease Central analgesic
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- 69. To summarize..Calcitonin 1. Source 2. Natureof hormone 3. Steps of Synthesis 4. Normal plasma concentration 5. Metabolism 6. Mechanism of action(Second messenger) 7. Physiological actions 8. Factors regulating secretion 9. Applied physiology
- 70. Vitamin D 1. Source 2.Nature of hormone 3. Steps of Synthesis 4. Normal plasma concentration 5. Metabolism 6. Mechanism of action(Second messenger) 7. Physiological actions 8. Factors regulating secretion 9. Applied physiology
- 71.
- 72. o Cholecalciferol o Steroid 2.Natureof hormone
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- 75. 5.Metabolism oHalf life: 15hours oMetabolized in the Liver
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- 77. 7.Physiological actions Acts onbone Acts on kidney Acts on small intestine
- 78. Effect on calcium level VitaminD increases plasma calcium levels Stimulating intestinal calcium absorption The active form of Vitamin D, 1,25-dihydroxyvitamin D3 (calcitriol), increases the amount of calcium the gut absorbs from food.
- 79. Effect on calciumlevel Vitamin D increases plasma calcium levels by Mobilizing calcium from bones • When serum calcium levels are low, calcitriol and parathyroid hormone (PTH) work together to release calcium from bones.
- 80. Effect on calcium level VitaminD increases plasma calcium levels by: •Increasing renal reabsorption of calcium •Calcitriol and PTH also increase the amount of calcium the kidneys reabsorb from the distal tubule.
- 81. Calcitriol increases renalNPT2a (sodium dependent phosphate cotransporter) expression and phosphate reabsorption, Intestinal NPT2b expression and phosphate absorption. Effect on Phosphate level
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- 84.
- 85. Calcium homeostasis oNormal level ofcalcium oCalcium distribution oFunction of calcium oRole of PTH oRole of Calcitonin oRole of vitamin D oApplied physiology
- 86. Calcium level in plasma Phosphatelevel in plasma PTH Calcitonin Vitamin D
- 87. Give reasons Tetany afterthyroidectomy Calcitonin escape Increased calcitonin in Zollinger Ellison syndrome
- 88. Case • Mr. RajeshGupta, 45 years M,office Worker; came with complaints of Mild fatigue and muscle weakness for the past 3 months,Occasional dull ache in the lower back and joints,Increased thirst and frequent urination noticed recently.
- 89. oInvestigations 1.Serum Calcium: 11.2mg/dL 2.Parathyroid Hormone (PTH):90 pg/mL 3.Serum Phosphate: 2.4 mg/dL 4.Renal Function Tests: Normal. 5.Neck Ultrasound: A 1.2 cm lesion detected near the lower pole of the right thyroid gland, suggestive of a parathyroid adenoma. What is your diagnosis?
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