Neonatal hypomagnesemia

Introduction to neonatal hypomagnesemia Normal neonatal serum magnesium is 0.81.15mmol/L (1.92.8mg/dl), ionic magnesium is 0.400.56mmol/L (0.971.36mg/dl), serum magnesium<0.66mmol/L (1.6mg/ Dl) is hypomagnesemia. basic knowledge The proportion of illness: 0.1% (the incidence rate in newborns is about 0.1%) Susceptible population: newborn Mode of infection: non-infectious Complications: hypokalemia, hypocalcemia, arrhythmia

Causes of neonatal hypomagnesemia

(1) Causes of the disease

1. Magnesium intake is reduced

(1) Premature infants: The fetus receives magnesium from the mother mainly 3 months after pregnancy.

(2) neonatal transient hypomagnesemia: transient, often accompanied by hypocalcemia.

(3) intrauterine growth retardation: placental transport magnesium barrier, fetal intake of magnesium decreased.

(4) Fasting.

2. Magnesium malabsorption

(1) Diarrhea: affects the absorption of magnesium by the intestines.

(2) Congenital magnesium absorption disorder: a genetic disease.

(3) Milk feeding: Due to the high intake of phosphorus, it affects the absorption of magnesium.

(4) Hepatobiliary diseases: can cause the absorption of magnesium in the intestines to decrease.

3. Too much magnesium loss

(1) renal tubular disease: hypoxia-ischemia, congenital abnormalities, etc. can reduce renal tubular reabsorption of magnesium.

(2) Drugs: Some drugs can inhibit the reabsorption of magnesium by the renal tubules and increase the excretion of urinary magnesium, such as diuretics and aminoglycoside antibiotics.

(3) Diabetic mothers and babies: Diabetic mothers have magnesium obstruction due to renal reabsorption, often with magnesium deficiency and hypoparathyroidism, leading to neonatal hypomagnesemia.

(4) Hypercalcemia: Hypercalcemia caused by any cause can cause hypomagnesemia.

(two) pathogenesis

The placenta actively transports magnesium to the fetus. During the fetus and delivery, the cord blood magnesium is higher than that of the mother. It begins to decline after birth. When the serum magnesium is low, the excitability of the nervous system is enhanced, and the neuromuscular conduction is strengthened. When the blood magnesium is reduced to 0.5mmol/ When L (1.2mg/dl) or less, clinically similar low-calcium convulsions can occur, mainly in small infants who are fed milk for less than 3 months, especially newborns.

Neonatal hypomagnesemia prevention

Pay attention to pregnancy health care, prevent and treat mothers with hypomagnesemia, prevent neonatal liver and intestinal diseases, so as to avoid the increase of magnesium absorption and increase the discharge. When there is excessive magnesium loss, attention should be paid to magnesium supplementation, milk-fed infants and thyroid When the gland function is low, the blood phosphorus is high, which can also cause the decrease of blood magnesium, which should be actively prevented.

Neonatal hypomagnesemia complications Complications hypokalemia hypocalcemia arrhythmia

Hypomagnesemia often associated with hypocalcemia, hypokalemia, with low calcium, mainly neuromuscular excitation, hypomagnesemia and hypocalcemia are difficult to identify in clinical manifestations, and many hypomagnesemia Often accompanied by hypocalcemia, therefore, in the treatment of hypocalcemia by calcium therapy, hypomagnesemia may be considered. In combination with hypokalemia, muscle weakness is the main cause, and potassium deficiency occurs when severe hypokalemia occurs. It is not easy to correct. Hypomagnesemia is an important cause of difficulty in correcting hypokalemia. This disease can be complicated by throat, apnea, asphyxia, and arrhythmia.

Neonatal hypomagnesemia symptoms common symptoms hypomagnesemia convulsion reflex hyperthyroidism block hypokalemia hypocalcemia tachycardia irritability dyspnea

The clinical manifestations are diverse and non-specific. Serum magnesium <0.5mmol/L (1.2mg/dl) can cause symptoms, but the severity is not completely parallel with the degree of serum magnesium reduction.

1. The neuromuscular system is mainly characterized by increased neuromuscular excitability, irritability, tremors, startle, gaze in both eyes, facial muscles or hand and foot convulsions, hyperreflexia, strong limbs, severe throat, apnea, suffocation .

2. Cardiovascular system hypomagnesemia can lead to increased excitability of cardiomyocytes, slowing of conduction, various types of arrhythmias can occur, such as pre-contraction, paroxysmal tachycardia, ventricular fibrillation, and conduction block.

3. Digestive system loss of appetite, nausea, vomiting, bloating.

4. Respiratory trachea, bronchial smooth muscle contraction, breathing difficulties can occur.

Examination of neonatal hypomagnesemia

1. Serum magnesium serum magnesium <0.66mmol / L can be diagnosed.

2. There is hypocalcemia due to hypomagnesemia can cause hypoparathyroidism, and the target organs such as kidney and bone respond to parathyroid hormone is also low, can not mobilize bone calcium into the blood, can not reduce renal tubular to phosphorus Reabsorption, so neonatal hypomagnesemia is often accompanied by hypocalcemia, and hypomagnesemia and hypocalcemia are difficult to distinguish in clinical manifestations, so serum calcium should be measured simultaneously in children with hypomagnesemia; Patients with hypocalcemia should also consider the possibility of hypomagnesemia when treated with calcium.

3. Urinary magnesium 24h urinary magnesium can reflect the actual situation more than blood magnesium. Urinary magnesium excretion <1.0mmol/L indicates magnesium deficiency in the body, but hypomagnesemia caused by renal tubular reabsorption of magnesium disorder, urinary magnesium excretion increases,>1.5 Mmmol/L.

The electrocardiogram showed early T wave high tip, QRS wave widened, severe PR interval prolonged, ST segment moved down, T wave flat, inverted, U wave appeared, QT interval was normal, and can be differentiated from hypocalcemia.

Diagnosis and diagnosis of neonatal hypomagnesemia

diagnosis

Hypomagnesemia should be highly suspected in the following situations: multiple electrolyte disorders; unexplained, difficult to correct hypocalcemia, hypokalemia; refractory arrhythmia; refractory heart failure; vomiting, sudden diarrhea After convulsions, and blood calcium supplementation, seizures still occur, combined with laboratory tests, blood magnesium is lower than normal can be diagnosed.

Differential diagnosis

Different from hypocalcemia, clinical 2/3 hypomagnesemia associated with hypocalcemia, therefore, children with ineffective calcium therapy should consider the possibility of hypomagnesemia, ECG and laboratory tests can be Help identification.

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