Hypocalcemic crisis in children

Hypocalcemic crisis in children is a condition characterized by increased neuroreflex excitability and attacks of tetany due to a persistent decrease in the level of calcium in the blood.

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Causes of hypocalcemic crisis

Hypocalcemic crisis may be a consequence of hypofunction of the parathyroid glands in idiopathic hypoparathyroidism or a consequence of impaired development of the parathyroid glands (isolated agenesis or dysgenesis of the parathyroid glands, Di George syndrome). Surgical operations, radioiodine therapy of thyroid diseases, malignant or granulomatous diseases and degenerative processes of the parathyroid glands are also of significant importance. This complication accompanies autoimmune damage to the parathyroid glands, is observed in hemochromatosis, thalassemia, Wilson's disease. The cause may be either insufficient secretion of parathyroid hormone, or insufficiency of the calcium-sensitive receptor gene or hypomagnesemia. In newborns, hypocalcemia may be idiopathic or mediated by maternal hyperparathyroidism, diabetes mellitus, asphyxia and prematurity.

Hypocalcemia sometimes occurs with hypersecretion of parathyroid hormone: if resistance develops to it or biologically inactive parathyroid hormone is secreted. Hypocalcemia can also be caused by conditions after treatment of Paget's disease and after treatment of diffuse toxic goiter, successful therapy of rickets, metastases of osteoblastic tumors (breast cancer and prostate cancer), vitamin D deficiency (impaired 25-hydroxylation, l-alpha-hydroxylation, enterohepatic regulation, alimentary deficiency, lack of ultraviolet radiation). Hypocalcemia also accompanies such diseases as malabsorption, steatorrhea, vomiting and diarrhea, short bowel syndrome, acute pancreatitis, alcoholism, chronic renal failure.

In addition, hypocalcemia can be of iatrogenic nature: with the introduction of phosphates (or as a consequence of their excess in food), ethylenediaminetetraacetic acid (EDTA), thiazide diuretics, the use of actinomycin, neomycin, laxatives, phenobarbital and other anticonvulsants, bone resorption inhibitors (calcitonin, bisphosphonates), with massive transfusion of citrated blood, operations in conditions of extracorporeal circulation.

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Symptoms of hypocalcemic crisis

The main symptom of hypocalcemia, regardless of its cause, is increased neuromuscular excitability and tonic convulsions. In newborns and young children, hypocalcemia is often asymptomatic, but in some cases signs of hyperexcitability are revealed: tremor of the chin, limbs, muscle twitching, clonus of the feet, shrill cry. Laryngospasm, respiratory disorders (tachypnea, episodes of apnea, inspiratory stridor), abdominal distension, vomiting, muscle hypotonia are possible.

Early symptoms: paresthesia, tingling of the lips and fingertips, twitching or nagging pain in the muscles. Typical are spasmodic contractions of the muscles of the forearm and hand ("obstetrician's hand"), feet ("equine foot"). Severe hypocalcemia leads to heart rhythm disturbances and decreased blood pressure. In relatively mild cases, convulsions are often provoked by factors that lead to a shift in the acid-base balance towards alkalosis - hyperventilation (screaming, crying, physical exertion, hyperthermia), use of diuretics, vomiting. The severity of clinical manifestations of tetany depends to a much greater extent on the rate of hypocalcemia than on the degree of calcium reduction in the blood.

Diagnosis criteria

Hypocalcemia is diagnosed if the level of total calcium in the blood of full-term newborns and older children is below 2 mmol/l (ionized calcium - below 0.75-0.87 mmol/l), and in premature newborns - below 1.75 mmol/l (ionized calcium - below 0.62-0.75 mmol/l).

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Emergency medical measures

In case of an attack of tetany, calcium salts are administered at a dose of 10-20 mg/kg in terms of calcium, or 10-15 ml of a 10% solution of calcium chloride or calcium gluconate - intravenously by jet stream slowly under pulse control (the administration is stopped if bradycardia appears). Then it is better to use a 1% solution 2-3 times a day or administer calcium gluconate through a catheter into the central vein by drip in a 0.9% solution of sodium chloride or in a 5% glucose solution. If necessary, intravenous administration of calcium preparations can be repeated every 6-8 hours. Then calcium preparations are prescribed orally at a dose of 50 mg/kg x day) (washed down with milk). If symptoms of latent tetany persist, a 25% solution of magnesium sulfate is administered at a dose of 0.2-0.5 ml/kg intravenously by jet stream.

The main drugs for maintenance therapy in the interictal period are various forms of vitamin D and calcium preparations. Calcium carbonate is preferable, as well as its combined soluble salts in a daily dose of 1-2 g (element). It should be borne in mind that excess protein foods rich in phosphorus (meat, eggs, liver) can provoke a hypocalcemic crisis.

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