Hypocalcemic tetany

hypocalcemic tetany

1. HYPOCALCEMIC TETANY by G.NAGARJUNA GOUD

2. Calcium

3. Calcium Calcium is the most abundant mineral in the body

4. Sources of calcium

5. Daily Requirements of Calcium

6. Metabolism of calcium

7. Metabolism of Calcium - Absorption

8. Factors affecting Calcium Absorption

9. Mechanism of Calcium absorption Calcium absorption occurs by 1,25(OH) 2 D 3 mediated mechanism.

10. Excretion of calcium

11. Distribution and storage of Calcium Plasma calcium : 9-11mg/100ml Ionized calcium: 4.65-5.25mg/100ml

12. Functions of Calcium

13. Regulation of enzyme activity

14. Regulation of plasma calcium

15. Regulation of plasma calcium

16. Disorders of calcium metabolism

17. Hypocalcemia

18. Hypocalcemia

19. Causes of hypocalcemia I. Factitious hypocalcemia : Is the reduction of the total , not the ionized fraction of serum calcium with reduction of serum albumin, the patient don't have any symptoms or signs of hypocalcaemia If the serum albumin levels fall to < 4 g/dl., the usual correction is to add 0.8 mg/dl to the measured total serum calcium for every 1.0 gm/dl reduction of serum albumin.

20. II. Hypoparathyroidism Hypoparathyroidism is the state of decreased secretion or decreased activity of PTH Manifestations that occur result from associated hypocalcemia and hyperphosphatemia .

21. Three categories of hypoparathyroidism Deficient PTH secretion (> 99% of all cases In ability to make an active form of PTH care. Inability of kidneys and bones to respond to parathyroid hormone being produced by normal parathyroid .

22. III. Magnesium depletion and hypocalcemia : Normal mg serum level is 1.6-2.1 mEq /L Mg metabolism has a close association with that of calcium: Are competitive for renal tubular reabsorption Are physiological antagonists in CNS Mg is necessary for PTH release and for its action Patients with hypocalcemia due to Mg deficiency should be treated with IV mg at a dose of 48 mEq over 24 hours.

23. IV. Hypocalcemia and hyper phosphatemia : 85% is free and only 15% is protein bound Hypocalcemia and tetany may occur if serum phosphorus rises rapidly Hyperphosphatemia alters calcium and phosphate ion solubility products, and calcium deposition in soft tissue may occur.

24. V. Medications and toxins causing hypocalcemia : Mithramycin , bisphosphonates, calcitionin , oral or parentral phosphate preparation, anticonvulsants manly (phenytoin or phenobarbital ) Plasmapheresis with citrated blood Radiographic contrast dyes Chemotherapeutic agents. During surgical procedures, hypocalcemia may occur in the absence of citrated bl. Infusion, may be due to acute hemodilution by physiological saline.

25. Hungry Bone syndrome Hypocalcemia and pancreatitis VIII. Hypocalcemia associated with critical illness.

26. IX.Vitamin D disorders resulting in hypocalcemia : Both inherited and a quired disorders of vit D and its metabolites may be associated with hypocalcemic disorder. Decreased synthesis of vit D3 in the skin may be due to lack of sun exposure Fat malabsorption Extensive liver disease Drugs, mainly anticonvulsant. Nephrotic syndrome, may be due to excretion of vit D binding protein. Ch. R.F. with reduction of GFR to <30% may present with  production of 1-25 dihydroxy vit D.

27. Hypocalcemia - Features

28. Hypocalcemia – Signs of Tetany

29. Differential diagnosis Hyperventilation syndrome in hystericals due to respiratory alkalosis. Rx- simple mask with rebreathing exercises and tranquilisers .

30. Management Dependent on the underlying cause and severity Administration of calcium alone is only transiently effective Mild asymptomatic cases: Often adequate to increase dietary calcium by 1000 mg/day Symptomatic: Treat immediately

31. I nvestigations Serum calcium Ionic calcium Serum magnesium Blood urea Serum creatinine Serum amylase & serum lipase Serum proteins;- total proteins,albumin,globulin Serum electrolytes PTH hormone immunoassay. Tests for vitamin D metabolites. Measurements of the urinary cyclic AMP response to exogenous PTH. 25(OH)D assays.

32. Hypocalcemia - Treatment

33. Rx for factitious hypocalcemia Low serum albumin levels can cause a reduction in the total, but not the ionized ,fraction of serum calcium. Each 1g/ dL reduction in the serum albumin concentration will lower the total calcium concentration by approximately 0.8mg/ dL without affecting the ionized calcium concentration.

34. -:Formula:- Thus ,calcium level should be corrected in patients with low serum albumin levels ,using the formula : Corrected calcium(mg/ dL ) = measured total Ca(mg/ dL )+0.8(4.0-serum albumin <g/ dL >), Where 4 respresents the average albumin level.

35. Acute hypocalcaemia: Calcium gluconate is the preferred IV calcium. Calcium gluconate contains 90 mg of elemental calcium/ 10 ml ampoule. Usually 1-2 ampoule (180 mg of elemental calcium) diluted in 50-100 ml of 5% dextrose, is infused over 10 minutes. This can be repeated until the patient's symptoms have cleared. The goals should be to raise serum calcium by 2-3 mg/dl with the administration of 15mg/kg of elemental calcium over 4-6 hours. Calcium should be maintained in the low normal range. If possible oral calcium supplementation should be initiated together with vit D.

36. ii- Chronic hypocalcemia Patients who are asymptomatic or with mild symptomatic hypocalcaemia can be treated with oral calcium and vit D. The overall goal of therapy is to maintain serum calcium in the low normal, range, serum calcium should be tested every 3-6 months.

37. Hypocalcemia with concurrent hypomagnesemia Often cannot correct the Ca unless the Mg is corrected Give 2 gm of Mg (16 meq ) of MgSO4 as a 10% solution over 10 to 20 minutes Followed by 1 gm MgSO4 (8 meq ) at 100 mL/ hr Continue intravenous MgSO4 as long as Mg < 1 mg/ dL Careful monitoring if patient has impaired renal function

38. Calcium salts Drug preparation: Ca = elemental calcium Calcium chloride (27.2% cal ) 10% solution (100 mg/ml) given IV but cause local irritation. Calcium gluconate . Calcium carbonate: 40% calcium e.g oscal, titralac. Calcium citrate 21% cal  (citracal). Calcium lacate 13% calcium.

39. Vit D preparation: Ergocalciferol : ( calciferol ) Calcifediol (25-hydoxy vit . ) Calcitriol : (1,25 dihydroxy vit D )

40. Vitamin D dosage in Rx of chronic hypocalcemia Simple dietary deficiency - can be corrected by the use of ergocalciferol 400-2000 IU/day However in conjunction with other hypocalcemic disorders (e.g., underlying impairments in vitamin D metabolism or renal insufficiency) larger doses may be needed e.g., a 6 to 8 week regimen of 50,000 units, dosed weekly Severe malnutrition or malabsorption – may require even higher doses