Chapter 43: Metabolic & Endocrine Emergencies

DISORDERS OF GLUCOSE HOMEOSTASIS

Most disorders of carbohydrate metabolism are related to diabetes mellitus (DM) and represent a broad category of emergency conditions. Toxin ingestion, medications, multisystem trauma, head injury, cardiovascular disease, cerebrovascular disease, and infection can mimic or exacerbate these conditions. Clinical appearance may vary dramatically. Patients may present with significant mental status changes or appear well while on the brink of metabolic decompensation.

DIABETIC KETOACIDOSIS

General Considerations

Diabetic ketoacidosis (DKA) is the most common acute life-threatening complication of diabetes. It is more commonly seen in type 1 diabetes but may occur in type 2. Patients with type 1 DM have an absolute insulin deficiency. When the production of insulin in the pancreas fails, the decreased glucose utilization creates a relative state of starvation. Counterregulatory hormones (cortisol, glucagon, catecholamine, and growth hormone) that help maintain blood glucose levels adequate for cellular function during fasting are stimulated. These hormones promote gluconeogenesis and glycogenolysis, increasing glucose levels, and lipolysis, which converts adipose to free fatty acids. Without insulin to allow cellular absorption of glucose, these mechanisms continue to produce glucose. Severe dehydration and electrolyte losses develop as the kidneys filter the highly osmotic glucose. Furthermore, free fatty acids that cannot enter the citric acid cycle without insulin are oxidized into ketones. These accumulate to cause metabolic acidosis, further electrolyte derangement, and exocrine pancreatic dysfunction.

Clinical Findings

A. History

If a diabetes history is elicited or known, ascertain potential precipitating causes of DKA:

• Noncompliance with insulin

• Recent or current infection of any type (most common)

• Injury or, trauma, recent surgery

• Cardiovascular: acute coronary syndrome or myocardial infarction (MI)

• Transient ischemic attack or stroke

• Medications (corticosteroids, thiazides, or sympathomimetics)

• Gastrointestinal (GI): gastroenteritis, GI bleed, acute or acute-on-chronic pancreatitis

• Endocrine: acromegaly or Cushing syndrome

• Ethanol or drug abuse

• Gastroenteritis or GI bleeding

• Medications: corticosteroids, diuretics, β-blockers, calcium channel blockers, sulfonylureas, antipsychotics, anticonvulsants

• Other: psychological problems, eating disorders, insulin pump malfunction and illegal substance abuse; psychosocial factors, such as depression or inability to afford medications, limiting compliance

• Noncompliance with insulin regimen due to psychological or physiologic reasons

Although noncompliance or misuse of insulin is a frequent cause of DKA, consideration of other causes of decompensation is imperative. Infection or illness may prompt patients to underdose. Up to 25% of DKA admissions result from new-onset diabetes. Alcoholic ketoacidosis (AKA), starvation, lactic acidosis, renal failure, or ingestions such as salicylates, methanol, ethylene glycol, or paraldehyde should be considered in the differential diagnosis of DKA.

B. Symptoms and Signs