Diabetic Ketoacidosis (DKA) for PLAB 1
Diabetic Ketoacidosis (DKA) is a life-threatening complication of diabetes mellitus, characterized by hyperglycemia, ketosis, and metabolic acidosis. Understanding its pathophysiology, clinical presentation, diagnosis, and management is crucial for PLAB 1 preparation, especially concerning UK guidelines.
Pathophysiology of DKA
Clinical Presentation
Patients with DKA often present with a rapid onset of symptoms, typically over 24-48 hours. Key signs and symptoms include:
| Symptom/Sign | Description |
|---|---|
| Polyuria & Polydipsia | Due to osmotic diuresis from hyperglycemia. |
| Nausea & Vomiting | Common, can be severe. |
| Abdominal Pain | Often diffuse and severe, can mimic acute abdomen. |
| Kussmaul Respiration | Deep, rapid breathing to compensate for metabolic acidosis. |
| Fruity Breath Odor | Due to acetone. |
| Dehydration | Tachycardia, hypotension, dry mucous membranes. |
| Altered Mental Status | From mild confusion to coma, especially in severe DKA. |
Diagnosis of DKA
The diagnosis of DKA is based on the presence of three key criteria, often referred to as the 'DKA Triad':
The diagnostic criteria for DKA are: 1. Hyperglycemia: Blood glucose level typically > 250 mg/dL (13.9 mmol/L). 2. Ketonemia or Ketonuria: Moderate to large amounts of ketones detected in blood or urine. 3. Metabolic Acidosis: Venous pH < 7.30 and/or serum bicarbonate < 18 mEq/L (mmol/L). Anion gap is typically elevated (often > 10-12 mEq/L). The anion gap is calculated as: (Sodium + Potassium) - (Chloride + Bicarbonate).
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Differential Diagnosis
It's important to differentiate DKA from other hyperglycemic emergencies, particularly Hyperosmolar Hyperglycemic State (HHS). While both involve hyperglycemia, DKA is characterized by significant ketosis and acidosis, whereas HHS typically has profound hyperosmolarity and dehydration with minimal or no ketosis.
Management of DKA (UK Guidelines Focus)
Management of DKA is a medical emergency requiring prompt and aggressive treatment. The primary goals are to correct dehydration, hyperglycemia, and acidosis, and to treat the underlying precipitating cause. The management follows a structured approach:
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1. Fluid Resuscitation
Intravenous fluid resuscitation is the first priority. Typically, isotonic saline (0.9% NaCl) is used initially. The rate of infusion depends on the degree of dehydration. Aim to restore intravascular volume and improve tissue perfusion.
2. Insulin Therapy
Once fluid resuscitation has begun and serum potassium levels are known to be > 3.3 mmol/L, an intravenous infusion of short-acting insulin (e.g., Actrapid) should be initiated. The typical starting dose is 0.1 units/kg/hour. The goal is to reduce blood glucose by 3-4 mmol/L per hour. Avoid rapid drops in glucose, which can lead to cerebral edema.
3. Electrolyte Correction
Potassium levels are critical. Insulin drives potassium into cells, so hypokalemia is a significant risk. Monitor potassium closely and supplement as needed. If serum potassium is < 3.3 mmol/L, insulin infusion should be delayed until potassium is corrected. Phosphate and magnesium levels should also be monitored and replaced if deficient.
4. Acidosis Management
Metabolic acidosis typically resolves with fluid resuscitation and insulin therapy. Intravenous bicarbonate is generally NOT recommended unless the pH is severely low (< 6.9) and there is hemodynamic instability, as it can paradoxically worsen intracellular acidosis and cause hypokalemia. Close monitoring of pH and bicarbonate is essential.
5. Identifying and Treating Precipitating Factors
DKA is often triggered by an underlying event. Common precipitants include infection (e.g., pneumonia, UTI), myocardial infarction, stroke, pancreatitis, non-compliance with insulin, new diagnosis of Type 1 diabetes, and certain medications (e.g., SGLT2 inhibitors, corticosteroids).
Hyperglycemia (> 250 mg/dL or 13.9 mmol/L), Ketonemia or Ketonuria, and Metabolic Acidosis (venous pH < 7.30 and/or serum bicarbonate < 18 mEq/L).
Isotonic saline (0.9% NaCl).
After fluid resuscitation has begun and serum potassium is > 3.3 mmol/L.
Remember that DKA is a medical emergency. Prompt recognition and management are key to preventing severe morbidity and mortality.
Learning Resources
Provides comprehensive, evidence-based guidance on the recognition, management, and follow-up of diabetic ketoacidosis, aligned with UK clinical practice.
An overview of Diabetic Ketoacidosis and Hyperosmolar Hyperglycemic State from a leading endocrine society, offering patient-centric information and clinical insights.
A detailed review article discussing the pathophysiology, diagnosis, and current management strategies for DKA, suitable for in-depth understanding.
A visual explanation of the step-by-step management of DKA, which can aid in understanding the flow of treatment.
Information from Diabetes UK explaining DKA in accessible terms, covering causes, symptoms, and what to do.
A comprehensive clinical resource providing detailed information on DKA and HHS, including diagnostic criteria and treatment protocols (requires subscription, but often accessible via institutional access).
A concise, peer-reviewed overview of DKA, covering its epidemiology, pathophysiology, clinical features, diagnosis, and management, useful for quick review.
A visual algorithm for the management of DKA, offering a quick reference for treatment steps and decision-making.
A broad overview of DKA, including its history, causes, symptoms, diagnosis, and treatment, providing a general understanding of the condition.
A clinical review article from the British Medical Journal focusing on the management of DKA in adults, offering insights into current best practices.