Any blood glucose value below 40mg/dl is considered
Major causes of hypoglycemia in an infant
Transient hypoglycemia in neonates
Small for gestational age
Neonates with perinatal asphyxia
Infants of a diabetic mother
Infants with erythroblastosis fetalis
Neonates born to mother with toxemia
Beta cell hyperplasia
Beckwith -Wiedmann syndrome
Major causes of hypoglycemia in an older infant & childHyperinsulinemic states
- Islet cell adenomas
- Islet cell dysmaturation syndrome
- Isolated growth hormone deficiency
- Addison's disease
- ACTH deficiency
- Ketotic hypoglycemia
- Glycogen storage disorder
- Fatty acid oxidation defects
Inborn Errors of Metabolism
- Maple Syrup Urine Disease (MSUD)
- Propionic Acidemia
- Acute alcohol intoxication
- Salicylate intoxication
- Fructose intolerance
- Excessive insulin administration in IDDM
- Extraneous insulin administration
- Renal failure
HyperinsulinismMost cases present during the 1st year of life as a result of familial or non-familial nesidioblastosis or islet cell dysmaturity syndrome. Islet cell adenoma usually present as hypoglycemia in a child 5 years or older.
The hallmark of hyperinsulin states is the inability to withstand fasting. Patients have ravenous appetites, increased demand for food and weight gain. Jitteriness and seizures are common. At the time of documented hypoglycemia, ketonemia is low or absent. There is no acidosis and S. insulin levels are usually higher than 5 to 10 mcg/ml with elevated C-peptide (In factitious hypoglycemia, due to exogenous administration of insulin, C-peptide is not elevated). Also S. insulin levels may be more than 100mcg/ml). Hyperinsulinism is confirmed by fasting for several hours under close supervision and collecting blood samples for testing. MRI or high-resolution ultrasonography may be helpful in locating a pancreatic adenoma. Surgery is the treatment of choice.
Ketotic hypoglycemiaIt is the most common cause of childhood hypoglycemia. It usually presents between the age of 18 months and 5 years and remits spontaneously by 8 to 9 years of age. Hypoglycemia usually occurs during illness when food intake is limited. Diagnosis is confirmed by fasting for several hours under close supervision and collecting blood samples for testing. At the time of hypoglycemia, there is associated ketonemia & ketonuria. S.alanine levels are reduced. Treatment consists of frequent feedings of a high-protein, high carbohydrate diet. During periods of illness, parents should check the child's urine for presence of ketones, as it appears several hours before hypoglycemia. If urine ketones are positive, liquids with high carbohydrate content should be given to the child.
Glycogen storage disorder
Glycogen synthetase deficiency (GSD Type 0) presents as early morning hypoglycemia. There is associated ketonemia but no hepatomegaly. Clinical picture is similar to ketotic hypoglycemia. Prolonged hyperglycemia after glucose administration with increase in serum lactate should indicate the deficiency. Hypoglycemia is unresponsive to glucagon administration as liver glycogen content is decreased.
Von Gierke's disease (GSD Type I): The kidneys and liver glycogen content in increased and liver and kidneys are enlarged. Patients may have "doll's face", stunted growth, and normal mental development. Along with hypoglycemia, there is lactic acidosis, hyperlipidemia, and hyperuricemia. IV glucagon (post-prandial) does not raise the blood glucose. Continuous nighttime feeding by tube is required.
GSD Type III: Patients have hepatomegaly. However the kidneys are not enlarged (as in GSD type I). Serum concentrations of uric acid, lactate, ketones and lipids are normal. IV glucagon (postprandial) raises the blood glucose level.
Fatty acid oxidation defectsHypoglycemia is associated with hypoketonemia. Patients usually present in the 2nd year of life and hypoglycemia is associated with encephalopathy mimicking Reye's syndrome. Diagnosis is established by evaluating plasma for organic acids and urine for dicarboxylic acid and enzyme studies from liver biopsy tissue or cultured fibroblasts.
Neonatal HypoglycemiaIn a newborn, glucose levels rapidly fall to a low point in the 1st 2 hours of life which is usually transient (as the source of maternal glucose is removed) and the infant achieves homeostasis. This transition is usually smooth but there are certain high risk infants who are at risk of hypoglycemia.
High risk infants:
Infants with increased utilization of glucose (Hyperinsulinism):
- Infants of Diabetic mothers
- Erythroblastosis fetalis
- Beckwith Wiedman syndrome
- Nesidioblastosis or islet cell adenoma.
Infants with decreased glucose stores / production:
- Premature infants
- Intra-uterine growth retardation (IUGR)
- Inadequate caloric intake
Increased utilization of glucose / stressed infants:
- Respiratory distress
Inborn errors of metabolism in infants:
- Glycogen storage disorders
- Organic acidemias
Endocrinal deficiencies in infants:
- Adrenal insufficiency
- Congenital hypopituitarism