Nonketotic hyperosmolar coma

Nonketotic Hyperosmolar Coma

Nonketotic hyperosmolar coma, also known as hyperosmolar hyperglycemic state (HHS), is a serious complication of diabetes mellitus, particularly type 2 diabetes. It is characterized by extreme hyperglycemia, hyperosmolarity, and dehydration without significant ketoacidosis. This condition requires prompt medical attention to prevent severe complications and mortality.

Pathophysiology

Nonketotic hyperosmolar coma occurs when there is a relative insulin deficiency and an increase in counter-regulatory hormones such as glucagon, cortisol, catecholamines, and growth hormone. This hormonal imbalance leads to increased hepatic glucose production and decreased peripheral glucose utilization, resulting in severe hyperglycemia. The high blood glucose levels cause osmotic diuresis, leading to dehydration and electrolyte imbalances.

Unlike diabetic ketoacidosis (DKA), there is enough insulin present to prevent lipolysis and ketogenesis, hence the absence of significant ketoacidosis. However, the severe dehydration and hyperosmolarity can lead to altered mental status and coma.

Clinical Presentation

Patients with nonketotic hyperosmolar coma often present with:

• Extreme hyperglycemia (blood glucose levels often exceeding 600 mg/dL)
• Severe dehydration
• Altered mental status, ranging from confusion to coma
• Polyuria and polydipsia
• Neurological deficits such as seizures or hemiparesis

Diagnosis

The diagnosis of nonketotic hyperosmolar coma is based on clinical presentation and laboratory findings, including:

• Plasma glucose > 600 mg/dL
• Serum osmolality > 320 mOsm/kg
• Absence of significant ketonemia or ketonuria
• Serum bicarbonate > 15 mEq/L
• Arterial pH > 7.3

Management

The management of nonketotic hyperosmolar coma involves:

• Fluid replacement: Rapid rehydration with intravenous fluids is crucial to correct dehydration and hyperosmolarity.
• Insulin therapy: Low-dose insulin infusion to gradually reduce blood glucose levels.
• Electrolyte management: Monitoring and correcting electrolyte imbalances, particularly potassium.
• Treatment of underlying causes: Identifying and treating precipitating factors such as infections, myocardial infarction, or medication noncompliance.

Prognosis

The prognosis of nonketotic hyperosmolar coma depends on the promptness of treatment and the presence of comorbid conditions. Mortality rates can be high, especially in elderly patients or those with significant comorbidities.

Prevention

Preventive measures include:

• Regular monitoring of blood glucose levels in diabetic patients
• Patient education on recognizing early symptoms of hyperglycemia
• Adherence to prescribed diabetes management plans

Also see

• Diabetic ketoacidosis
• Type 2 diabetes mellitus
• Hyperglycemia
• Insulin therapy