hypocalcemia endocrinology and metabolism.pptx

hypocalcemia

1. hypocalcemia Dr \Omar Elsharkawy

2. FUNCTIONS of Calcium 1. Muscle contraction 2. Neuromuscular / nerve conduction 3. Intracellular signalling 4 . Bone formation 5 . Coagulation 6 . Enzyme and hormone regulation 7 . Maintainance of plasma membrane stability

3. introduction 1.2 kg to 1.4 kg of Ca is present normally in human Body 99% - in the skeleton Remaining amount -distributed in the ECF(0.25%) and other soft tissues(0.75 %)  

4. In Blood , total Ca concentration is normally 8.5-10.5 mg/dl, of which approx 50% is ionized(normal value-4.8 mg/dl) Remainder is bound ionically to negatively charged proteins- Predominantly albumin and immunoglobulins or lossely complexed with PO4 , citrate ,SO4 and other anions

5. Protein binding of calcium Influenced by pH: . Metabolic acidosis decrease protein binding increase ionized calcium. Metabolic alkalosis increase protein binding,decrease ionized calcium.

6. What is hypocalcemia ? Hypocalcemia a decrease in the SERUM CALCIUM <8.5mg/dl or IONIZED CALCIUM < 3-4.4mg/ dL

7. Factors affecting calcium absorption a)Factors favoring calcium absorption – - An acidic pH - Presence of sugar acids, organic acids and citric acid - Presence of Vit D

8. Factors favoring …… - State of health and intact mucosa - A healthy adult absorb about 40% of dietary calcium - PTH stimulates the activation Vit D, thus indirectly increased absorption of Vit D - High protein diet- Lysine and Agraine causes maximal absorption

9. b) Factors inhibiting absorption of calcium - Alkaine pH - High fat diet - Dietary fiber in excess absorption - Excess phosphates, magnesium and iron decrease absorption - Glucocorticoids reduces intestinal absorption of calcium - Oxalic acid found in spinach , phytic acid found in bran القمح , wholegrain cereals and the seed coats of beans and grains الفاصوليا - Advancing age

10. Regulation of calcium homeostasis Three principle hormones are involved in calcium homeostasis - Vit D - PTH - Calcitonin Acting at three target organs • Intestine • bone and • kidney

11. Causes of hypocalcemia

12. hypoalbuminemia Hypoalbuminemia is the most common cause of hypocalcemia. Causes include cirrhosis, nephrosis , malnutrition, burns, chronic illness, and sepsis. In patients who are critically ill has no clinical significance because the active fraction (ionized) is not affected. However, to prevent missing a second hypocalcemic disorder, measure the ionized calcium level whenever the albumin level is low . Or measure corrected ca

13. hypoparathyrodism

14. Hypomagnesemia The mechanism of hypocalcemia includes resistance to PTH in the bone and kidneys, as well as a decrease in PTH secretion

15. Vitamin D deficiency Vitamin D is a necessary cofactor for the normal response to PTH, and ca absorbtion from GIT . Poor nutritional intake, chronic renal insufficiency, or reduced exposure to sunlight may cause vitamin D deficiency.

16. Role of vit . d

17. Current Recommended Dietary Allowances (RDAs) for vitamin D are: - 600 IU of vitamin D per day for adults for individuals from 1 to 70 years (15 microgram) - 800 IU per day for those over 70 years.  

18. Hepatic disease Impaired 25-hydroxylation of vitamin D Decreased bile salts with malabsorption of vitamin D Decreased synthesis of vitamin D–binding protein

19. Kidney disease - Chronic kidney disease leads to a decrease in the conversion of 25-hydroxyvitamin D to its active form 1,25-dihydroxyvitamin D, particularly when the glomerular filtration rate (GFR) falls below 30 mL /min . - hyperphosphatemia

20. Hungry bone syndrome Post parathyroidectomy Hypocalcemia results if the rate of skeletal mineralization exceeds the rate of osteoclast-mediated bone resorption.

21. Acute pancreatitis When the pancreas is damaged, free fatty acids are generated by the action of pancreatic lipase. Insoluble calcium salts are present in the pancreas, and the free fatty acids avidly chelate the salts, resulting in calcium deposition in the retroperitoneum

22. hyperphosphatemia  Phosphate binds calcium avidly causing acute hypocalcemia hyperphosphatemia may also result from renal failure or excess tissue breakdown because of rhabdomyolysis or tumor lysis.

23. drugs Blood transfusion:citrate chelate ca Some radiographic contrast dyes may contain (EDTA), which chelates calcium in serum Cinacalcet inhibit PTH release Cisplatin (chemotherapy) can induce hypocalcemia by causing hypomagnesemia Bisphosphonates suppress osteoclast Phenytoin : decrase ca absorption Proton pump inhibitors (PPIs) and histamine-2 receptor blockers ( eg , cimetidine ) decrase ca absorption

24. acute Management Mild Hypocalcemia In patients whose symptoms are not life-threatening , confirm ionized hypocalcemia and check other pertinent laboratory tests. If the cause is not obvious, send a blood sample for a PTH level. Depending on the PTH level, the endocrinologist may do further laboratory workup, particularly an evaluation of vitamin D levels. Oral repletion may be indicated for outpatient treatment; recommended dose of elemental calcium in healthy adults is 1-3 g/d

25. IV replacement is recommended in symptomatic or severe hypocalcemia (total less7.5 ,ionized less 4)with cardiac arrhythmias or tetany. Doses of 100-300 mg of elemental calcium (10 mL of calcium gluconate contains 90 mg elemental calcium; 10 mL of calcium chloride contains 272 mg elemental calcium) in 50-100 mL of 5% dextrose in water (D5W) should be given over 5-10 minutes.

26. Calcium infusion drips should be started at 0.5 mg/kg/ hr and increased to 2 mg/kg/ hr as needed, with an arterial line placed for frequent measurement of ionized calcium. Measure serum calcium every 4-6 hours to maintain serum calcium levels at 8-9 mg/ dL . 

27. Chronic management in patients with severe hypoparathyroidism , vitamin D treatment may be required; however, remember that PTH deficiency impairs the conversion of vitamin D to calcitriol. Therefore, the most efficient treatment is the addition of 0.5-2 mcg of calcitriol or 1-alpha-hydroxyvitamin D 3 Nutritional vitamin D deficiency from lack of sunlight exposure or poor oral intake of vitamin D responds to treatment with ultraviolet light or sunlight exposure . preparations containing 1-2 g of elemental calcium per day can treat patients with a calcium deficiency.