Discuss the causes of hypocalcaemia?

  • Hypoparathyroidism,
  • Vitamin D deficiency
  • Magnesium deficiency
  • Malabsorption (ass with Vit D and Mg deficiency)
  • Hyperphosphatemia due to renal failure or tumour lysis.

Discuss the diagnosis?

Serum calcium levels corrected for albumin level

Discuss the clinical features?

  • Tetany can occur when serum calcium falls below 1.8-1.9 mmol/l. It may be mild (perioral numbness, paresthesias of hand and feet, muscle cramps) or severe (carpopedal spasm, laryngospasm, focal or generalised seizures)
  • Hypocalcaemia can cause dementia and psychological symptoms (anxiety and depression) in adults
  • Hypocalcaemia can cause papilloedema

Discuss the treatment?

Mild asymptomatic hypocalcaemia
Increase dietary calcium intake (unless the patient has hyperphosphatemia).

Symptomatic hypocalcaemia

  • IV Calcium- The most appropriate treatment (unless low Mg) is IV calcium. 10 ml of 10% Calcium gluconate (2.25 mmol of elemental calcium) or 10mls of 10% calcium chloride (6.75 mmol of elemental calcium). The calcium should be given slowly over 10-20 minutes to avoid the risk of serious cardiac dysfunction. Such infusions raise the serum calcium concentration for 2-3 hours, and therefore should be followed by a slow infusion of calcium. The optimum dose should be 1.25mmol per hour for a 50 kg man. The calcium should be diluted in dextrose and water or saline. Calcium gluconate is preferred to calcium chloride because it is less likely to cause tissue necrosis if extravasated.
  • Oral calcium- Intravenous calcium should be continued until the patient is receiving an effective regimen of oral calcium and vitamin D. Calcitriol,( in a dose of 0.25 to 0.5 µg/day), is  preferred in patients with severe acute hypocalcemia because of its rapid onset of action (hours).
  • Magnesium- Hypomagnesemia is a common cause of hypocalcemia, both by inducing resistance to PTH and by diminishing its secretion. Thus, an alternative approach, if the serum magnesium concentration is not known (or is low), and if renal function is normal (so that excess magnesium can be excreted), is to administer magnesium. Two grams (4ml of 50%) of magnesium sulfate should be infused as a 10 percent solution over 10 minutes, followed by 1 gram in 100 mL of fluid per hour.

Chronic hypocalcaemia associated with hypoparathyroidism.

1.5-2 g of elemental calcium should be given orally (Calcium carbonate-250mg of elemental Ca/650 mg tablet)
Vitamin D should be added if there is insufficient response (50,000 units/day of vitamin D or its equivalent as calcitriol).

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