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Metabolic Disorders
Calcium Imbalance
Chloride Imbalance
Gaucher's Disease
Glycogen Storage Diseases
Lactose Intolerance
Magnesium Imbalance
Metabolic Acidosis
Metabolic Alkalosis
Phosphorus Imbalance
Potassium Imbalance
Sodium Imbalance
Syndrome of Inappropriate Antidiuretic Hormone Secretion
Tay-Sachs Disease


What is Hypoglycemia ?

Hypoglycemia is a potentially dangerous, abnormally low blood glucose level. It occurs when glucose burns up too rapidly, when the glucose release rate falls behind tissue demands, or when excessive insulin enters the bloodstream. When the brain is deprived of glucose, as with oxygen deprivation, its functioning becomes deranged. With prolonged glucose deprivation, tissue damage - or even death-may occur.

Hypoglycemia may be classified as reactive or fasting. Reactive hypoglycemia results from the body's reaction to digestion or from the administration of excessive insulin.

Fasting hypoglycemia causes discomfort during periods of abstinence from food. Blood glucose levels decrease gradually. This rare type of hypoglycemia occurs most commonly in the early morning before breakfast.

Manifestations of hypoglycemia tend to be vague and depend on how quickly the patient's glucose levels drop. Gradual onset of hypoglycemia produces predominantly central nervous system (CNS) signs and symptoms; a more rapid decline in plasma glucose levels results predominantly in adrenergic signs and symptoms.

Causes of Hypoglycemia

The two forms of hypoglycemia have different causes and occur in different types of patients.

Reactive hypoglycemia

Several forms of reactive hypoglycemia occur. In a diabetic patient, it may result from administration of too much insulin or less commonly too much oral antidiabetic medication. In a mildly diabetic patient (or one in the early stages of diabetes mellitus), reactive hypoglycemia may result from delayed and excessive insulin production after carbohydrate ingestion.

Similarly, a nondiabetic patient may suffer reactive hypoglycemia from a sharp increase in insulin output after a meal. Sometimes called postprandial hypoglycemia, this type of reactive hypoglycemia usually disappears when the patient eats something sweet.

In some patients, reactive hypoglycemia has no known cause (idiopathic reactive) or may result from total parenteral nutrition for gastric dumping syndrome or from impaired glucose tolerance.

Fasting hypoglycemia

Fasting hypoglycemia usually results from an excess of insulin or insulin-like substance or from a decrease in counterregulatory hormones. It can be exogenous. resulting from external, factors, such as alcohol and drug ingestion, or endogenous, resulting from organic problems.

Endogenous hypoglycemia may result from tumors or liver disease. Insulinomas - small islet cell tumors in the pancreas - secrete excessive amounts of insulin, which inhibits hepatic glucose production. The tumors are benign in 90% of patients.

Extrapancreatic tumors, although uncommon, can also cause hypoglycemia by increasing glucose utilization and inhibiting glucose output. Such tumors occur primarily in the mesenchyma, liver, adrenal cortex, GI system, and lymphatic system. They may be benign or malignant.

Among non endocrine causes of fasting hypoglycemia are severe liver diseases, including hepatitis, cancer, cirrhosis, and liver congestion associated with heart failure. All these conditions reduce the uptake and release of glycogen from the liver.

Some endocrine causes include destruction of pancreatic islet cells; adrenocortical insufficiency, which contributes to hypoglycemia by reducing the production of cortisol and cortisone needed for gluconeogenesis; and pituitary insufficiency, which reduces corticotropin and growth hormone levels.

Causes in infants and children

Hypoglycemia is at least as common in neonates and children as it is in adults. Usually, infants develop hypoglycemia because of the increased number of cells per unit of body weight and because of increased demands on stored liver glycogen to support respirations, thermoregulation, and muscle activity.

In full-term neonates, hypoglycemia may occur 24 to 72 hours after birth and is usually transient. In infants who are premature or small for gestational age, onset of hypoglycemia is much more rapid-it can occur as soon as 6 hours after birth-due to the infants' small, immature livers, which produce much less glycogen. A rare cause of hypoglycemia in infants is nesidioblastosis, a benign condition of the insulinproducing islet cells. The treatment is surgical.

Maternal disorders that can produce hypoglycemia in infants within 24 hours after birth include diabetes mellitus, pregnancy-induced hypertension, erythroblastosis, and glycogen storage disease.

Signs & Symptoms of Hypoglycemia

Patients feel shaky, nervous, tired, sweaty, cold, hungry, confused, irritable or impatient. It's always important to test to be sure that Patients actually are having low blood sugar.

Symptoms of hypoglycemia include:

  • Nervousness and shakiness
  • Dizziness or light-headedness
  • Feeling anxious or weak
  • General discomfort, uneasiness, or ill feeling

Diagnostic Tests

Glucometer readings provide quick screening methods for determining blood glucose levels.

Laboratory testing confirms the diagnosis by showing decreased blood glucose values. The following values indicate hypoglycemia:

  • full-term neonates -less than 30 mg/dl before feeding, less than 40 mg/dl after feeding
  • preterm neonates -less than 20 mg/dl before feeding, less than 30 mg/dl after feeding.
  • children and adults - less than 40 mg/dl before a meal. less than 50 mg/dl after a meal.

In addition, a 5-hour glucose tolerance test may be administered to provoke reactive hypoglycemia. Following a 12-hour fast, laboratory testing to detect plasma insulin and plasma glucose levels may identify fasting hypoglycemia.

A C-peptide assay is used to help diagnose fasting hypoglycemia. It also differentiates fasting hypoglycemia caused by an insulinoma from fasting hypoglycemia caused by insulin injections.


Reactive hypoglycemia requires dietary modificatior to help delay glucose absorption and gastric emptying. Usually, this includes small, frequent meals; avoidance of simple carbohydrates (including alcohol and fruit drinks); and ingestion of complex carbohydrates, fiber, and fat. The patient may also receive amicholinergic drugs to slow gastric emptying and iptestinal motility and to inhibit vagal stimulation of insulin release.

For fasting hypoglycemia, surgery and drug therapy may be required. In patients with insulinoma, removal of the tumor is the treatment of choice. Drug therapy may include nondiuretic thiazides such as diazoxide to inhibit insulin secretion; streptozocin and hormones, such as glucocorticoids; and long-lasting glycogen.

For infants who have hypoglycemia or are at risk for developing it, therapy includes preventive measures. A hypertonic solution of dextrose 10% in water, calculated at 5 to 10 ml/kg of body weight, administered I.V. over 10 minutes and followed by 4 to 8 mg/kg/minute for maintenance should correct a severe hypoglycemic state in neonates. To reduce the chance of hypoglycemia in highrisk infants, feedings - of either breast milk or a solution of dextrose 5% to 10% in water-should begin as soon after birth as possible.

ALERT: For severe hypoglycemia (producing confusion or coma), initial treatment is usually I.V. administration of a bolus of 25 or 50 g of glucose as a 50% solution. This is folIowed by a constant infusicrt of glucose until the patient can eat a meal. A patient who experiences adrenergic reactions without CNS. symptoms may receive oral carbohydrates (parenteral, therapy isn't required).

Prevention Tips

Diabetics should follow their doctors' advice regarding diet, medications, and exercise.

Pregnant diabetic women should maintain careful control of their blood sugar. Gestational diabetes that occurs during pregnancy, is diagnosed by repeat testing of expectant mothers. Upon delivery, routine blood sugar levels are taken from the infant until he/she no longer has low blood sugar.

People who are known to experience hypoglycemia should keep a snack or drink containing sugar available at all times to take as soon as symptoms appear. If symptoms do not improve in 15 minutes, additional food should be eaten. A glucagon kit is available by prescription for episodes of hypoglycemia that respond poorly to other types of treatment.

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