Hypocalcemia in newborns

Hypocalcemia is the concentration of total calcium in the serum of less than 8 mg / dL (less than 2 mmol / l) in term infants and less than 7 mg / dL (less than 1.75 mmol / L) in premature infants. It is also defined as the ionized calcium level of less than 3.0-4.4 mg / dL (less than 0.75-1.10 mmol / L), depending on the method used (type of electrode). Manifestations include hypotension, apnea, and tetany. Treatment of hypocalcemia - intravenous or oral administration of calcium.

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What causes hypocalcemia?

Hypocalcemia of newborns can be early (in the first 2 days of life) or late (more than 3 days); hypocalcemia with late onset is rare. In some children with congenital hypoparathyroidism [eg, with Di-Georgi syndrome with agenesis or dysgenesis of parathyroid glands], both early and late (prolonged) hypocalcemia are noted.

Risk factors for early hypocalcemia include prematurity, low weight to gestation, maternal diabetes, intranatal asphyxia. The mechanisms vary. Normally, parathyroid hormone helps maintain a normal level of calcium, when the constant intake of ionized calcium through the placenta terminates at birth. Transient, relative hypoparathyroidism can cause hypocalcemia in premature and some small to the term of gestation of newborns whose parathyroid glands do not yet function adequately; as well as in children from mothers with diabetes or hyperparathyroidism, as in these women the level of ionized calcium during pregnancy is higher than normal. Intrathatal asphyxia can also increase the level of calcitonin, which inhibits calcium release from the bones, leading to hypocalcemia. Other neonates have no normal kidney response to parathyroid hormone, expressed in phosphaturia; An elevated level of phosphate (P04) leads to hypocalcemia.

Symptoms of hypocalcemia

Symptoms of hypocalcemia rarely occur if total calcium does not decrease less than 7 mg / dL (less than 1.75 mmol / L) or the level of ionized calcium does not decrease less than 3.0 mg / dl. Manifestations include hypotension, tachycardia, tachypnea, apnea, difficulty in feeding, agitation, tetany and convulsions. Similar symptoms can be noted with hypoglycemia and withdrawal syndrome.

Diagnosis of hypocalcemia

The diagnosis is made based on the level of decrease in total or ionized calcium in the blood serum; ionized calcium is a more physiological indicator, because it excludes the influence of protein level and pH. Elongation of the corrected interval QT (QT.) On the ECG also indicates hypocalcemia.

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Treatment of hypocalcemia

Early-onset hypocaenia usually lasts for several days, and infants with a calcium level greater than 7 mg / dL (greater than 1.75 mmol / L) or ionized calcium greater than 3.5 mg / dl who have no clinical signs of hypocalcaemia are rarely required treatment. Preterm infants with calcium levels less than 7 mg / dl (less than 1.75 mmol / L) and premature infants with calcium levels less than 6 mg / dL (less than 1.5 mmol / L) should be treated by slow intravenous administration for 30 minutes 10 % solution of calcium gluconate at the rate of 2 ml / kg (200 mg / kg). Too fast administration can cause a bradycardia, therefore it is necessary to monitor heart rate during infusion. It is also necessary to carefully monitor the site of intravenous administration, as tissue infiltration with a calcium solution acts irritatingly and can cause local tissue damage or necrosis.

After an emergency correction of hypocalcemia, it is possible to administer long-term calcium gluconate together with other solutions for intravenous administration. Beginning with the administration of 400 mg / (kg day) of calcium gluconate, the dose can be gradually increased to 800 mg / (kg day) if necessary, to prevent the resumption of hypocalcemia. When the baby starts to feed through the mouth, the mixture can be enriched with the same daily dose of calcium gluconate by adding 10% calcium gluconate solution to the mixture. Usually additional calcium intake is necessary for several days.

If hypocalcemia begins late, then it is necessary to add calcitriol or additional calcium to the infant's mixture to ensure a Ca: P044: 1 ratio until normal calcium levels are maintained. Calcium preparations for oral administration contain a large amount of sucrose, which can lead to diarrhea in premature infants.