neonatal hypocalcemia
Introduction
Introduction to neonatal hypocalcemia The normal serum total calcium of newborns is 2.252.75mmol/L (911mg/dl), when serum total calcium is less than 2.0mmol/L (8mg/dl) or serum is lt;0.9mmol/L (3.6mg/dl) For hypocalcemia, neonates are prone to hypocalcemia. It is one of the important reasons for neonatal seizures. basic knowledge The proportion of illness: 0.02% Susceptible people: infants and young children Mode of infection: non-infectious Complications: hypomagnesemia, sudden death, convulsion in children
Cause
Causes of neonatal hypocalcemia
(1) Causes of the disease
Calcium balance mainly depends on the regulation of parathyroid gland and calcitonin. If the regulation function is abnormal, or the fetal calcium deficiency or excessive phosphorus intake after birth can cause hypocalcemia, the specific causes are as follows:
1, early hypocalcemia occurred within 2 days after birth, mostly due to temporary parathyroid function inhibition, because the amount of calcium in the pregnant mother's blood through the placenta active input of the fetus increased in the late pregnancy, inhibited the parathyroid gland Function, low birth weight infants, asphyxia and neonatal parathyroid function with respiratory distress syndrome are worse than normal newborns in full-term, calcium storage is less, the incidence is higher, some people have a few days after birth The calcitonin in the blood is higher, and it is also related to hypocalcemia. The blood calcium in the early onset is often lower than 1.75mmol/L.
2, late hypocalcemia occurred 3 days after birth, peak in the first weekend, more common in milk-fed newborns, due to excessive phosphorus intake, blood calcium decreased, blood calcium value is often less than 2.00mmol / L.
3, a small number of congenital hypoparathyroidism caused by hypocalcemia, the incidence can be early or late, the symptoms lasted for more than 3 weeks, but most of the children with the growth of parathyroid function with age Can catch up with normal babies, so it is still temporary.
4, occasionally pregnant mother suffering from hyperparathyroidism or adenoma, I can be asymptomatic, but high blood calcium, severely inhibit the fetal parathyroid function, the baby appears persistent hypocalcemia after birth, sometimes newborn This disease is a clue to the diagnosis of maternal thyroid tumors.
(two) pathogenesis
Calcium is the most abundant mineral in the human body. At the end of pregnancy, 20 to 30 g of elemental calcium is stored in full-term newborns, 80% of which is actively transported from the placenta 3 months after pregnancy. 99% of total calcium. In the bone, only about 1/3 can be exchanged with extracellular fluid. Plasma calcium exists in three different forms and maintains a dynamic balance. About 40% is combined with plasma protein (mainly albumin), which is called protein-bound calcium. It can not diffuse through the capillary wall to the interstitial fluid, but when the blood calcium is lowered, it can gradually release calcium ions to maintain the blood calcium in the normal range; about 10% with anions such as tannic acid, phosphoric acid, carbonic acid, sulfuric acid, etc. Combined, it plays a role in the deposition and dissolution of bone salt, which is called complex calcium, and about 50% is free.
Prevention
Neonatal hypocalcemia prevention
1. Encourage breastfeeding and feed it within 6 hours of birth.
2, pregnant mother should be set daily for outdoor activities, increase nutrition, especially when the gastrocnemius tendon is found in the late pregnancy, blood calcium should be checked, calcium supplementation.
Complication
Neonatal hypocalcemia complications Complications, hypomagnesemia, sudden death, convulsion
Can be complicated by vomiting, blood in the stool, apnea, suffocation, and even sudden death, may also be complicated by hypomagnesemia, hyperphosphatemia.
Symptom
Neonatal hypocalcemia symptoms Common symptoms Hypocalcemia, startle, convulsions, tremor, diabetes, baby, sleeping, shaking head, suffocation, intracranial hemorrhage
1, may have diabetes or pregnancy-induced hypertension during pregnancy, premature infants and those with a history of asphyxia are more common.
2, more than a few hours after birth to 2 days of onset, there are uneasiness, startle, limb tremor, throat, convulsions, etc., the interictal period is generally good.
3. Blood calcium is less than 3.5 mmol/L (7 mg/dl) or free calcium is less than 1.75 mmol/L (3.5 mg/dl).
4, early hypocalcemia often occurs within 72 hours of birth, seen in premature infants, low birth weight children, all kinds of dystocia, suffering from intracranial hemorrhage, asphyxia, sepsis, acidosis with alkaline fluid and maternal diabetes, pregnancy-induced hypertension And hyperparathyroidism, asymptomatic hypocalcemia in premature infants can often be naturally relieved, but still need oral calcium gluconate.
5, late hypocalcemia refers to low blood calcium occurred 72 hours to 3 weeks after birth, mostly for full-term children, and artificial feeding, high proportion of phosphorus in milk affects the absorption of calcium, this type of hypocalcemia Hand and foot spasms may occur in term infants or premature infants.
6, the symptoms are different, mainly manifested as restlessness, startle, tremors and convulsions, occasionally throat and apnea, the child is generally in good condition in the new period, but the muscle tension is slightly higher, the tendon reflex is enhanced, normal newborns The face nerve test (Foss feature) is positive, so there is no diagnostic significance.
Examine
Examination of neonatal hypocalcemia
1. Serum total calcium <1.75 mmol / L (7 mg / dl).
2. Serum free calcium <0.9mmol / L (3.5mg / dl) serum phosphorus is often > 2.6mmol / L (8mg / dl).
3.1,25-(OH)2D3 reduction, low plasma protein, acidosis, hypoxemia or alkalosis, or elevated blood phosphorus.
5. Urine calcium qualitative test is negative.
6. Do brain CT examination, except for convulsions caused by intracranial lesions.
7. Chest X-ray examination to understand the heart and lungs.
4. ECG QT interval prolongation (premature infant > 0.2 seconds, full-term infant > 0.19 seconds) suggest hypocalcemia.
Diagnosis
Diagnosis and diagnosis of neonatal hypocalcemia
Differential diagnosis
1. Hypoglycemia Hypoglycemia and hypocalcemia can occur in early neonates, but hypoglycemia is more common in low birth weight infants, while hypocalcemia occurs in any type of newborn.
2, hypomagnesemia (hypomagnesemia) The average blood magnesium of newborns is 0.82mmol / L (2.0mg / dl), when the blood magnesium is less than 0.62mmol / L (1.5mg / dl), called hypomagnesemia, Symptoms are similar to hypocalcemia. They are difficult to identify and can exist at the same time. Blood biochemical tests are helpful for diagnosis.
3, hypoxic-ischemic encephalopathy mostly occurs in premature infants and asphyxia, intracranial ultrasound examination is helpful for diagnosis.
4, DiGeorge syndrome manifested as permanent parathyroid insufficiency, with thymus deficiency, immunodeficiency and small jaw deformity, sometimes accompanied by aortic arch abnormalities, symptoms of recurrent low-calcium convulsions, chest X-ray film without thymus, there are Help with identification.
