Tests
1st tests to order
plasma glucose level
Test
Plasma glucose is >600 mg/dL.
Result
elevated
serum or urinary ketone level
Test
Beta-hydroxybutyrate is the main product of ketogenesis, with acetoacetic acids constituting the remainder of the ketones.
Guidelines recommend that the nitroprusside reaction may be used to detect ketones, but direct measurement of beta-hydroxybutyrate should be undertaken whenever possible.[2][47]
When measuring serum ketones, the nitroprusside reaction will not detect beta-hydroxybutyrate. Thus, serum or urine ketones measured by the nitroprusside reaction may be initially negative at the time of presentation, or remain positive when diabetic ketoacidosis (DKA) has resolved (giving the appearance that there are no ketones in the serum, or that DKA is not resolving).
Result
negative or low
serum BUN level
Test
Increased owing to volume depletion.
Result
elevated
serum creatinine level
Test
Increased owing to volume depletion (pre-renal azotemia).
Result
elevated
serum sodium level
Test
Usually low due to osmotic flux of water from the intracellular to the extracellular space in the presence of hyperglycemia.
The total sodium deficit is 5 to 13 mEq/L. Hypernatremia in the presence of hyperglycemia indicates profound volume depletion.
Result
variable; usually low but hypernatremia may be present
serum potassium level
Test
The total potassium deficit is 4 to 6 mEq/L owing to increased diuresis.
However, serum potassium is usually elevated owing to an extracellular shift of potassium caused by insulin insufficiency, hypertonicity, and acidemia.
Low potassium level on admission indicates severe total-body potassium deficit.[2]
Result
usually elevated; decreased in severe cases
serum chloride level
Test
The total chloride deficit is 5 to 15 mEq/kg.
Result
usually low
serum magnesium level
Test
The total body deficit of magnesium is usually 1 to 2 mg/dL owing to increased magnesium loss from diuresis.
Result
usually low
serum calcium level
Test
The total body calcium deficit is usually approximately 1 to 2 mg/dL owing to increased calcium loss from diuresis.
Result
usually low
serum phosphate level
Test
The total body phosphate deficit is 3 to 7 mg/dL owing to increased phosphate loss from diuresis.
Result
usually low
serum osmolality
Test
Effective serum osmolality is calculated from serum concentrations of sodium and glucose.[2] BUN concentration is not taken into account, because it is freely permeable and its accumulation does not change the osmotic gradient.[2]
Total serum osmolality is also based on sodium and glucose concentrations, but includes BUN.
Coma, if present, is most often due to hypernatremia rather than hyperglycemia resulting in osmolality >320 to 340 mOsm/kg.
Result
≥320 mOsm/kg
anion gap calculation
Test
Anion gap is calculated as (Na)-(Cl + HCO3) as mEq/L.
Levels ≥12 mEq/L signify an anion gap acidosis (i.e., lactic or ketoacidosis).[2]
Result
variable; usually 7 to 9 mEq/L
serum lactate level
blood gas
Test
Venous pH sample is usually 0.03 units lower than arterial pH.
Several studies have suggested that the difference between venous and arterial pH samples is not sufficiently significant to change clinical management.[47]
Result
arterial pH usually >7.30; arterial bicarbonate is >15 mEq/L
urinalysis
Test
Infection is the major precipitating factor occurring in 30% to 60% of patients. Urinary tract infections and pneumonia are reported most commonly.[4][9][10][11] Mild ketonuria is sometimes seen.
Result
variable; positive for glucose; positive for leukocytes and nitrites in the presence of infection; negative or only mildly positive for ketones
liver function tests
Test
Abnormalities may exist if underlying diseases, such as fatty liver or congestive heart failure, are present.
Result
usually normal
CBC
Test
Leukocytosis is present in hyperglycemic crises. However, leukocytosis >25,000 per microliter may indicate infection and requires further evaluations.[2]
Result
leukocytosis
Tests to consider
chest x-ray
ECG
Test
Used to identify precipitating cardiovascular diseases, such as myocardial infarction (MI), or if severe electrolyte abnormalities are present.[2]
Evidence of hypo- (U waves) or hyperkalemia (tall T waves) may be present.
Result
may show evidence of MI or hyperkalemia or hypokalemia
cardiac biomarkers
Test
Should be tested if an myocardial infarction (MI) is suspected as the trigger.
Result
may be elevated in the presence of MI
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