Investigations

Investigations carried out in DKA patients include:

• serum glucose level
  • usually greater than 250 mg/dL (13.9 mmol/L)
• arterial blood gas measurement
  • pH varies from 7.00 to 7.30
  • measurement of venous pH is recommended for monitoring treatment
• serum electrolytes (electrolytes on blood gas machine give a guide until accurate results available)
  • bicarbonate level - <18 mmol/L (18 mEq/L)
  • serum sodium level - usually low
  • serum potassium - may be low, normal, or elevated
  • magnesium – usually low but can be normal
• blood urea nitrogen, creatinine levels
  • usually elevated because of dehydration and decreased renal perfusion
• serum ketone level
• urinalysis
  • confirms the presence of glucose and ketones
  • positive for leukocytes and nitrites in the presence of infection
• anion gap
  • elevated anion gap >10-12 mmol/L (>10-12 mEq/L)
  • anion gap = ([Na mmol/L] – ([Cl mmol/L] + [HCO3 mmol/L])
• serum osmolality
  • greater than 320 mmol/kg (320 mOsm/kg) ()
  • plasma osmolality = 2 ([Na mmol/L] + [K mmol/L]) + [Urea mmol/L] + [glucose mmol/L]

Other investigations carried out according to the clinical indications are:

• ECG – to assess the effect of potassium status; rules out ischemia or myocardial infarction
• chest x-ray - if pneumonia or pulmonary disorder is suspected
• urine and blood cultures - if infection is suspected
• PCV & FBC - leucocytosis is common in DKA and does not necessarily indicate sepsis (1,2,3)

Note:

• bedside monitoring has been shown to be helpful in the clinical situation of diabetic ketoacidosis
  • portable blood ketone analysers, analysers for blood gas and electrolyte measurement if available will give results within a few minutes
  • therefore, glucose, ketones and electrolytes, including bicarbonate and venous pH, should be assessed at or near the bedside

Reference:

• (1) Westerberg DP. Diabetic ketoacidosis: evaluation and treatment. Am Fam Physician. 2013;87(5):337-46.
• (2) British Society of Paediatric Endocrinology and Diabetes (BSPED) 2013. Guidelines for the management of DKA in young people under the age of 18 years
• (3) Kitabchi AE et al. Management of hyperglycemic crises in patients with diabetes. Diabetes Care. 2001;24(1):131-53