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Neonatal hypoglycemia

Definition

Neonatal hypoglycemia is low blood sugar (glucose) in the first few days after birth.

Causes, incidence, and risk factors

Babies need sugar (glucose) for energy. Most of that glucose is used by the brain.

The developing baby gets glucose from the mother through the placenta. After birth, the baby gets glucose by producing it in the liver and from food.

Glucose levels can drop if:

• There is too much insulin in the blood (hyperinsulinism). Insulin is a hormone that pulls glucose from the blood into the cells to be used for energy.
• There is not enough glycogen, the form in which glucose is stored in the body.
• The baby is not producing enough glucose.
• The baby’s body is using more glucose than is being produced.

Neonatal hypoglycemia occurs when the newborn’s glucose level is below the level considered acceptable for the baby's age.

Hypoglycemia is the most common metabolic problem in newborns. It occurs in approximately 1 - 3 out of every 1,000 births.

Infants with the following risk factors are at high risk for neonatal hypoglycemia:

• Blood infection (sepsis)
• Endocrine disorders, such as low thyroid hormone production (hypothyroidism)
• Inborn errors of metabolism
• Intrauterine growth restriction
• Lack of oxygen shortly after birth
• Large for gestational age
• Mother with diabetes
• Mother with chorioamnionitis or infection around the time of the baby's birth
• Premature birth
• Small for gestational age

Symptoms

Infants with hypoglycemia may not have symptoms. If they do occur, symptoms may include:

• Bluish-colored skin (cyanosis)
• Breathing problems
• Decreased muscle tone (hypotonia)
• Grunting
• Irritability
• Listlessness
• Nausea, vomiting
• Pale skin
• Pauses in breathing (apnea)
• Poor feeding
• Rapid breathing
• Problems with maintaining body heat
• Shakiness
• Sweating
• Tremors
• Seizures

Signs and tests

Newborns at risk for hypoglycemia should have a blood test to measure blood sugar levels every few hours after birth. The health care provider should continue taking blood tests until the baby’s blood sugar level is consistently normal.

Other possible tests:

• Newborn screening for metabolic disorders
• Urine tests

Treatment

Infants with hypoglycemia may need to receive:

• Feeding with breast milk or formula within the first few hours after birth, either by mouth or through a tube inserted through the nose into the stomach (nasogastric lavage)
• A sugar solution through a vein (intravenously) if the baby is unable to feed by mouth, or if the blood sugar is very low

Treatment normally continues for a few hours or days to a week.

If the low blood sugar continues, the baby may also receive medication to increase blood glucose levels (diazoxide) or to reduce insulin production (ocreotide).

In rare cases, newborns with very severe hypoglycemia who don’t improve with treatment may need surgery to remove part of the pancreas (to reduce insulin production).

Expectations (prognosis)

The outlook is good for newborns who do not have symptoms, or who have hypoglycemia that gets better with treatment. However, hypoglycemia can return in a small percentage of babies after treatment.

The condition is more likely to return when babies are taken off intravenous feedings before they are fully ready to eat by mouth.

Babies with symptoms are more likely to develop problems with learning. This is especially true for babies with lower-than-average weight or whose mothers have diabetes.

Complications

Severe or long-term hypoglycemia may lead to brain damage, affecting normal mental function. Complications may include:

• Developmental delay
• Heart failure
• Seizures

Calling your health care provider

Call your health care provider if your baby has symptoms of neonatal hypoglycemia.

Prevention

If you have diabetes during pregnancy, work with your health care provider to control your blood sugar levels. Be sure that your newborn's blood sugar levels are monitored after birth.

References

Stanley CA, Baker L. The causes of neonatal hypoglycemia. N Engl J Med. 1999 Apr 15;340(15):1200-1.

Cornblath M, Hawdon JM, Williams AF, Aynsley-Green A, Ward-Platt MP, Schwartz R, Kalhan SC. Controversies regarding definition of neonatal hypoglycemia: suggested operational thresholds. Pediatrics. 2000;105:1141-1145.

Still BJ, Kliegman RM. The endocrine system. In: Behrman RE, Kliegman RM, Jenson HB, eds. Nelson Textbook of Pediatrics. 17th ed. Philadelphia, Pa: Saunders Elsevier;2004:chap 96.