Diabetic Ketoacidosis

written by Susan Tyler, Dal medical student, Feb 2009

last reviewed:

 

 

Introduction

The four major diagnostic criteria are hyperglycemia, anion gap metabolic acidosis, hyperketonemia, ketonuria. It is due to low levels of insulin and increased levels of counter-regulatory hormones such as glucagon, epinephrine, and cortisol. 

 

 

 

The Case of...

a simple case introducing clincial presentation and calling for a differential diagnosis to get students thinking.

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Causes and Risk Factors

DKA is more common in Type 1 DM than type II, due to complete insulin deficiency and counter-regulatory hormones.

 

It is precipitated by the 7 I’s:

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Pathophysiology

An increase in fatty acid oxidation leads to ketone produce acetone, beta-hydroxybutyrate, and aceto-acetate.leads to an anion gap metabolic acidosis.

 

Increased glucose production in liver leads to hyperglycemia and osmotic diuresis, with glycosuria and ketonuria. The resulting dehydration and electrolyte changes can lead to a drop in Na (pseudohyponatremia).

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Signs and Symptoms

  • history
  • physical exam

History

Frequency of sugar checks

Previous meal.

 

Hyperglycemia, dehydration, and electrolyte disturbances can lead to:

  • polyuria
  • polydipsia
  • polyphagia or anorexia
  • fatigue
  • abdominal pain - can be substantial
  • nausea and vomiting
  • blured vision

Assess for signs of infection

  • fever, chills
  • GI, respiratory, urinary

 

Evaluate the course and control of his diabetes

Physical Exam

 

vitals

 

dehydration

  • postural hypotension
  • tachycardia
  • JVP
  • dry mucous membranes
  • reduced skin turgor

 

shortness of breath and Kussmaul respiration (laboured, tachypnic breathing in response to metabolic acidosis)

 

decreased LOC (drowsiness -> stupor -> coma)


fruity smelling breath (acetone)


signs of infection

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Investigations

  • lab investigations
  • diagnostic imaging

Lab Investigations

Blood

  • blood glucose increased (11- 55 mM) and ketonemia required for diagnosis
  • ABG: anion gap acidosis with possible secondary respiratory alkolosis
  • pseudohyponatremia
  • normal or increased K, even though total body K depletion occurs
  • low bicarbonate
  • increased BUN/Cr (prerenal azotemia)
  • drop in PO4

causes

  • white count? to assess for infection
  • increased osmolality
  • tox screen
  • amylase and lipase, though can be elevated in DKA independent of pancreatitis

 

 

Urine: + glucose/ketones

Diagnostic Imaging

 

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Differential Diagnosis

 

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Treatments

Don't treat the blood sugar - treat the anion gap acidosis. Degree of DKA monitored by anion gap, but check the glucose hourly. Most institutions have a protocol - follow these instructions.

 

ABCs

Monitor especially if patient is in a stupor/coma


Rehydration

The aim is to give 3-4L over 8 hours. 1L/h normal saline first 2 hrs, then 300-500 ml/h 0.45% NS. Once glucose reaches 13.9 mM, switch to D5W and keep in 13.9 to 16.6 mM range.

 

Caution: aggressive rehydration can lead to overhydration and even cerebral edema in pediatric patients! Carefully monitor HR, BP, urine output, JVP.

 

Insulin therapy

CRITICAL to reverse acidosis.
Bolus insulin R with 0.1-0.15u/kg, maintenance drip 0.1ukg/h insulin R
When AG is normal, switch over to subcutaneous insulin (overlap IV and SC 2-3 H)

 

Potassium

Hypokalemia is a concern once acidosis is corrected, as K is globally depleted and further shifts into cells
If K 3.5 to 5.5 mM add KCl 20-40 mEq/L IVF (target range is 3.5 to 5)
Caution with K replacement in renal failure, may need to defer if Cr is high

 

pH

If ph < 7.0, low BP, arrhythmia, or coma, give bicarbonate in half normal saline.

 

Pediatrics

If severe vascular decompensation, give a 10 cc/kg bolus with 0.9% NaCl over 30 minutes. Reassess after bolus, repeat if necessary, and otherwise continue.

No vascular decompensation

Start insulin after first hour of initial rehydration. Use short-acting (regular) insulin infusion at 0.1 U/kg/h. Do not give a bolus, as this has been associated with cerebral edema.

Use 0.9% NaCl initially, then switch to 0.45% NaCl and add D5W when BG ~15-17

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Consequences and Course

DKA carries a 2-5% mortality with marked morbidity from complications. Patients are at increased risk of

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Resources and References

coming soon!

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Topic Development

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