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Calcium metabolism, rickets and osteomalacia

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CALCIUM METABOLISM

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Calcium metabolism, rickets and osteomalacia

  1. 1. CALCIUM METABOLISM, RICKETS AND OSTEOMALACIA R.SETHUPATHY FINAL YEAR MBBS STANLEY MEDICAL COLLEGE August 6, 2015 1
  2. 2. CALCIUM  Blood coagulation  Muscle contraction  Transmission of nerve impulses  Formation of skeleton ,etc. Total body calcium – 1100 g 99 % in bones
  3. 3. CALCIUM LEVELS IN THE BODY Plasma calcium : 9 – 11 mg / dL {5 mEq / L or 2.5 mmol / L}
  4. 4. GLOMERULAR FILTRATE 250 mmol DIET 25mmol (1000 mg) GIT FECES 22.5mmol ABSORPTION 15 mmol SECRETION 12.5 mmol REABSORPTION 247.5 mmol ECF 35 mmol URINE 2.5 mmol BONE EXCHANGEABLE 100 mmol STABLE 27,200 mmol RAPID EXCHANGE 500 mmol REABSORPTION 7.5 mmol FORMATION
  5. 5. CALCIUM REGULATION August 6, 2015 5  1,25 Dihydro cholecalciferol  Parathyroid hormone  Calcitonin  Parathyroid hormone related protein (PTHrP)  Miscellaneous hormones : Glucocorticoids, Growth hormone, Estrogen
  6. 6. 7 DEHYDROCHOLESTEROL SUNLIGHT VITAMIN D3 CHOLECALCIFEROL 25 HYDROXYLASE 25-HYDROXY CHOLECALCIFEROL 24α HYDROXYLASE 24, 25 DI-HYDROXY CHOLECALCIFEROL 1, 25 DI-HYDROXY CHOLECALCIFEROL 1α HYDROXYLASE VITAMIN-D August 6, 2015 6 SKIN LIVER KIDNEY
  7. 7. FUNCTIONS OF VITAMIN-D August 6, 2015 • Increases calcium absorption in intestine 7
  8. 8. FUNCTIONS August 6, 2015 8 • Promotes phosphate absorption by the intestines. • Decreases renal excretion of calcium & phosphate. • Increases both bone resorption and bone mineralization
  9. 9. PARATHYROID HORMONE • FOUR parathyroid glands located behind the thyroid gland CHIEF CELLS PRE PRO PTH PRO PTH PTH
  10. 10. ACTION OF PTH August 6, 2015 In addition, Increases the phosphate excretion in kidneys 10
  11. 11. CALCITONIN August 6, 2015 11 • Produced by the parafollicular cells / C cells of thyroid gland. STRUCTURE:  Molecular weight – 3500  Aminoacids-32
  12. 12. ACTION OF CALCITONIN • Decreases absorptive action of osteoclasts. • Deposits exchangeable Ca in bone salts. • Decreases the formation of osteoclasts. August 6, 2015 12 DECREASES SERUM CALCIUM LEVEL
  13. 13. PARATHYROID HORMONE RELATED PROTEIN ( PTHrP) • Produced by different tissues of our body • Binds to PTH receptors • Marked effect on growth and development of cartilage in utero. • Defect in PTHrP – severe skeletal deformities.
  14. 14. LONG TERM GLUCOCORTICOIDS glucocorticoids Inhibits osteoclasts Decrease calcium level Inhibits calcium and phosphate absorption from intestine Increases Ca and P excretion osteoporosis Decreases osteoblast activity SHORT TERM
  15. 15. GROWTH HORMONE Increases intestinal absorption of Calcium IGF – I Stimulates protein synthesis in bone ESTROGENS Prevents osteoporosis by inhibiting certain cytokines INSULIN Increases bone formation
  16. 16. RICKETS • Disease of growing bone • Occurs in children before fusion of epiphysis August 6, 2015 16 OSTEOID FORMATION OF BONES IS NORMAL MINERALISATION OF OSTEOID IS INADEQUATE SOFTENING OF BONES AND DEFORMITIES
  17. 17. PATHOPHYSIOLOGY OF RICKETS August 6, 2015 17
  18. 18. Rickets classification Type 1 rickets Type 2 rickets August 6, 2015 18
  19. 19. TYPE 1 RICKETS NUTRITIONAL RICKETS •Commonest rickets in developing countries •<4 years CONGENITAL VITAMIN-D DEFICIENCY •Maternal vitamin -D deficiency during pregnancy INTESTINAL RICKETS •Decreased calcium absorption in conditions like sprue, steatorrhoea, celiac disease. RENAL RICKETS •Renal osteo-dystrophy, Vitamin-D resistant rickets, fanconi syndrome, renal tubular acidosis RICKETS DUE TO HEPATIC FAILURE •Failure of liver hydroxylation of Vitamin-D DEFECTS IN VITAMIN D METABOLISM
  20. 20. TYPE 2 RICKETS Decreased phosphate intake Decreased phosphate absorption Increased phosphate excretion
  21. 21. CLINICAL SYMPTOMS IRRITABILITY FAILURE TO THRIVE FREQUENT FRACTURES PROFUSE SWEATING PROTRUDING ABDOMEN HYPOCALCEMIC SYMPTOMS DELAYED WALKING August 6, 2015 21
  22. 22. CLINICAL SIGNS HEAD • Delayed closure of anterior fontanelle. • Frontal bossing.
  23. 23. CRANIOTABES • Softening of cranial bones leads ping-pong ball consistency of the cranial bones. • Detected by applying pressure at the occiput or parietal bones.
  24. 24. THORAX • Rachitic Rosery • Harrison’s sulcus • Pigeon chest deformity
  25. 25. EXTREMITIES -Enlargement of wrists and ankle -Valgus or varus deformities -Windswept deformity -Bowing of long bones -Coxa vara.
  26. 26. BACK • Scoliosis • Kyphosis • lordosis
  27. 27. RADIOLOGICAL FINDINGS THICKENING OF THE GROWTH PLATE
  28. 28. CUPPING AND FRAYING OF METAPHYSIS
  29. 29. INCREASED TRANSLUCENCY OF BONES
  30. 30. LABORATORY FINDINGS serum calcium serum phosphorus serum alkaline phosphatase August 6, 2015 30
  31. 31. TREATMENT VITAMIN D 6,00,000 IU SINGLE DOSE GOOD RESPONSE 400 IU/DAY VITAMIN D POOR RESPONSE REPEAT THE INITIAL DOSE GOOD RESPONSE 400 IU/DAY VITAMIN D POOR RESPONSE REFRACTORY RICKETS FURTHER INVESTIGATIONS August 6, 2015 31 Symptomatic hypocalcemia –100 mg/kg  IV calcium gluconate followed by oral calcium or calcitrol -0.05mcg/kg/day
  32. 32. DEFORMITIES CORRECTION August 6, 2015 32 MILD DEFORMITY MERMAID SPLINTS ORTHOPAEDIC SHOES SEVERE DEFORMITY CORRECTIVE OSTEOTOMIES
  33. 33. PREVENTION 1.Exposure to sunlight 2.Food fortified with Vitamin A and Vitamin D. 3.Daily intake of 400 IU vitamin D by supplementation. 4.Lactating mothers should receive supplementation with milk or vitamin D to ensure prevention of rickets in their babies.
  34. 34. OSTEOMALACIA • osteopenia with disordered calcification leading to higher proportion of osteoid (unmineralized) tissue after epiphyseal closure (in adulthood) • Insidious in onset • Same pathogenesis as rickets August 6, 2015 34
  35. 35. CLINICAL PRESENTATION :
  36. 36. Radiological findings • Looser’s zone • Triradiate pelvis • Protrusio acetabuli August 6, 2015 36
  37. 37. LABORATORY FINDINGS serum calcium serum phosphorus serum alkaline phosphatase August 6, 2015 37 Bone marrow biopsy is the gold standard for the diagnosis of osteomalacia
  38. 38. TREATMENT • Treatment of the underlying cause. • Vitamin D supplementation • PO4 supplements if low serum PO4 is present • Ca supplements for calcium deficiency August 6, 2015 38
  39. 39. August 6, 2015 39

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