blood analysis

Hypocalcemia

What is hypocalcemia?

Hypocalcaemia is a clinical condition characterized by a calcium defect in the blood. It becomes concrete when the total calcemia falls below 9 mg / dL in the adult or when the free fraction (ionized calcium) falls below 4.5 mg / dL.

Regulation of Calcemia

In the article dedicated to calcemia, we saw how the blood levels of the mineral depend on the joint activity of vitamin D and two hormones, parathormone (PTH) and calcitonin, which in turn modulate the deposit / release of calcium from the bones, as well as its renal resorption / excretion and the degree of absorption at the enteric level.

Ultrasound of the thyroid: the removal or trauma of the parathyroid glands during a thyroidectomy (total or partial removal of the thyroid), are a common cause of hypoparathyroidism, in turn responsible for hypocalcemia.

We also explained how calcium is found in two distinct forms in the blood, in about equal proportions: the free fraction (ionized calcium) and the fraction linked to plasma proteins such as albumin. Since only the calcium excreted from these proteins is metabolically active, the free fraction assay is more accurate in assessing the clinical condition of patients with hypocalcemia. For example, in the case of a reduction in plasma proteins there is a percentage increase in the free fraction and this is why the total calcemia must be corrected according to the following formula, in order to give it a correct clinical meaning:

Correct total serum calcium = Total measured calcemia + [(4.0 - albuminemia g / dL) * 0.8]

Symptoms

Hypocalcemia causes an increase in muscle excitability, with the appearance of the so-called tetanic syndrome. Among the most precocious symptoms of hypocalcemia we recall the sensation of numbness or tingling around the mouth, and of tingling and numbness of the fingers; if the hypocalcemia is more severe the tingling changes into tetanic cramps (obstetric hand, Trosseau's sign), up to convulsions. In the most serious conditions, palpitations and severe cardiac arrhythmias arise which, together with laryngospasm, can endanger the patient's life. Symptoms of mild chronic hypocalcemia can precipitate under conditions such as pregnancy, emotional or physical stress and breastfeeding.

Causes

Possible causes of hypocalcemia include:

  • Hypoparathyroidism (inactivity of the parathyroid glands),
  • resistance to the action of parathormone,
  • reduced calcium intake with the diet due to malnutrition
    or malabsorption,
  • vitamin D deficiency,
  • resistance to the action of vitamin D,
  • intestinal resection,
  • rickets and other bone diseases,
  • excess phosphorus,
  • chronic magnesium deficits,
  • Achilia,
  • achlorhydria
  • acute magnesium excess,
  • acute pancreatic inflammation,
  • chronic renal failure,
  • burns,
  • alcoholism,
  • taking anticonvulsant drugs (barbiturates, hydantoins).

Treatment

See also: Drugs for treating hypocalcemia

Medical therapy is based on the determination and correction of the cause of hypocalcemia (to identify it the diagram shown in the figure can be useful, clicking on it to enlarge it). Regarding hypocalcemia itself, this is corrected through the administration of calcium supplements (calcium gluconate, calcium lactate, calcium chloride, etc.) and vitamin D, to be taken 30 minutes before meals, preferably with a glass of milk (except for manifest intolerance lactose or other contraindications). Acute hypocalcemia must instead be promptly corrected by injecting calcium chloride or calcium gluconate to the nearest emergency room.