HYPOCALCEMIA

In medicine, hypocalcaemia is the presence of low serum calcium levels in the blood, usually taken as less than 2.2 mmol/L or 9mg/dl or an ionized calcium level of less than 1.1 mmol/L (4.5 mg/dL). It is a type of electrolyte disturbance. It mainly occurs due to a deficiency of parathyroid hormone, inefficient parathyroid hormone, or deficiency of Vitamin D. It may be seen alongside hypomagnesemia.

Animals

Farm animals, mainly cows, can suffer hypocalcaemia (or milk fever) after calving. This is due to a large calcium demand and a slow response from the animal in terms of intestinal absorption or bone resorption. If a cow or other animal is affected it will collapse and have muscle spasms. It will eventually enter a coma and can die.

The treatment is injection with calcium gluconate. It can be prevented in part by avoiding excess calcium, or more commonly, by regulating potassium in the diet before calving.

Cause

• Absent parathyroid hormone (PTH)
  • Hereditary hypoparathyroidism
  • Acquired hypoparathyroidism
  • Hypomagnesemia
• Ineffective PTH
  • Chronic renal failure
  • Absent active vitamin D
    • Decreased dietary intake
    • Decreased sun exposure
    • Defective Vitamin D metabolism
      • Anticonvulsant therapy
      • Vitamin-D dependent rickets, type I
  • Ineffective active vitamin D
    • Intestinal malabsorption
    • Vitamin-D dependent rickets, type II
  • Pseudohypoparathyroidism
• Deficient PTH
  • Severe acute hyperphosphatemia
    • Tumor lysis syndrome
    • Acute renal failure
    • Rhabdomyolysis (initial stage)
  • Osteitis fibrosa following parathyroidectomy
• Exposure to hydrofluoric acid

Effects

• Perioral tingling and parasthesia, 'pins and needles' sensation over the extremities of hands and feet. This is the earliest symptom of hypocalcemia.
• Tetany, carpopedal spasm are seen.
• Trousseau sign (eliciting carpal spasm by inflating the blood pressure cuff and maintaining the cuff pressure above systolic)
• Chvostek's sign (tapping of the inferior portion of the zygoma will produce facial spasms)

The above two signs are indicative of latent tetany

• Tendon reflexes are depressed.

Laryngospasm and cardiac arrhythmias are life threatening complications.

Management:

• Two ampoules of intravenous calcium gluconate 10% is given slowly in a period of 10 minutes, or if the hypocalcemia is severe, calcium chloride is given instead.
• Maintenance dose of calcium is necessary to prevent further decline.

See also

• Calcium metabolism
• Hypercalcaemia
• Calcium deficiency (plant disorder)

External links

• Cleveland Clinic

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