Hypoglycemia
Hypoglycemia: Excerpt from In a Page: Signs and Symptoms
Hypoglycemia causes release of glucagon, growth hormone, and catecholamines, which rapidly mobilize liver glycogen to provide fuel (elevated epinephrine causes the symptoms of hypoglycemia). Hypoglycemia rapidly causes neurologic dysfunction (may be irreversible), as glucose is the brain's primary source of energy. Hypoglycemia is a very common problem in diabetic patients. Patient education about coordinating the timing of hypoglycemic administration, diet, and exercise is the key to preventing repeated episodes of hypoglycemia.
Differential Diagnosis
- Exogenous insulin administration is the most common cause of hypoglycemia
–Most commonly occurs in patients with known diabetes mellitus
–May occur with inadequate food ingestion or excessive exercise after an insulin injection
–May occur with delayed absorption of food (e.g., diabetic gastroparesis)
–Rarely, may occur as part of attention seeking behavior (i.e., factitious)
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Oral hypoglycemic medications (e.g., sulfonylurea)
–This is especially common with severe liver disease, which prevents gluconeogenesis
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Other medications (e.g., salicylates, sulfonamides, tetracyclines, warfarin, MAO inhibitors, phenothiazines)
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Reactive hypoglycemia occurs 2–4 hours after meals, due to delayed and exaggerated insulin release (associated with a family history of type II diabetes)
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Hypothyroidism
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Malnutrition/fasting
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Insulinoma/islet cell hyperplasia
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Alcohol consumption
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Sepsis
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Renal failure
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Sarcomas
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Pituitary or adrenal insufficiency
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Congenital hormone or enzyme defects
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Severe hepatic dysfunction (e.g., hepatitis, hepatic toxins, hepatic necrosis)
Workup and Diagnosis
- History and physical examination
–Medication, diet, and exercise history
–Associated symptoms include tachycardia, diaphoresis, tremor, anxiety, hyperventilation, and hyperthermia
–CNS symptoms may include dizziness, headache, confusion, convulsions, mental status changes, abnormal behavior, and coma
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Immediately measure serum glucose in any patient with altered mental status—missed diagnosis may result in irreversible neurologic damage or unnecessary procedures (e.g., intubation)
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Clinical symptoms of hypoglycemia usually begin to occur when the blood glucose level reaches 50 mg/dL; however, in diabetes, symptoms may begin at higher blood glucose levels or not at all
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Initial laboratory studies include serum or finger-stick glucose level, CBC, electrolytes, BUN/creatinine, magnesium, and urinalysis
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Consider LFTs, urinalysis, chest X-ray, TSH, cortisol, alcohol level and drug screen, head CT, blood cultures, and lumbar puncture if etiology is unclear
- Measure C-peptide and insulin before glucose infusion
–Serum insulin is elevated by insulinomas (insulin:glucose ratio >0.3) and sulfonylurea or exogenous insulin administration
–C-peptide is produced during endogenous insulin production; thus, decreased after exogenous insulin use; increased in insulinoma, sulfonylureas - CT/MRI may be necessary to evaluate for insulinoma
Treatment
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Glucose therapy (therapy goal is glucose >100 mg/dL)
–Alert patients may be repleted with oral glucose (e.g., juice, glucose tablets) or IV D50
–Patients with altered consciousness require IV D50 solution
–In children, use bolus of 25% dextrose
–Frequently recheck blood glucose
Glucagon may be used to increase glucose release from the liver if unable to obtain IV access and the patient cannot tolerate oral glucose; less effective in alcoholic and malnourished patients
Octreotide may be used in cases of sulfonylurea-induced hypoglycemia to inhibit insulin release
Thiamine must be given with glucose in any suspected case of alcohol abuse or nutritional deficiency to avoid Wernicke's encephalopathy
Hydrocortisone should be administered if blood glucose remains persistently low to rule out adrenal insufficiency
Book Source Details
- Book Title: In a Page: Signs and Symptoms
- Author(s): Scott Kahan, Ellen G. Smith
- Year of Publication: 2004
- Copyright Details: In a Page: Signs and Symptoms, Copyright © 2004 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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More About This Book:
Title: In a Page: Signs and Symptoms
Authors: Scott Kahan, Ellen G. Smith
Publisher: Lippincott Williams & Wilkins
Copyright: 2004
ISBN: 1-4051-0368-X
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