Investigations

1st investigations to order

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Plasma glucose is >600 mg/dL.

Result

elevated

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Beta-hydroxybutarate is the main product of ketogenesis, with acetoacetic acids constituting the remainder of the ketones.

Guidelines recommend that, in addition to using the nitroprusside reaction to detect ketones, direct measurement of beta-hydroxybutarate should be undertaken whenever possible.[1][42]

When measuring serum ketones, the nitroprusside reaction will not detect beta-hydroxybutarate. 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

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Increased owing to volume depletion.

Result

elevated

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Increased owing to volume depletion (pre-renal azotemia).

Result

elevated

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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/kg. Hypernatremia in the presence of hyperglycemia indicates profound volume depletion.

Result

variable; usually low but hypernatremia may be present

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The total potassium deficit is 4 to 6 mEq/kg owing to increased diuresis.

However, serum potassium is usually elevated owing to extracellular shift of potassium caused by insulin insufficiency, hypertonicity, and acidemia.

Low potassium level on admission indicates severe total-body potassium deficit.[1]

Result

usually elevated; decreased in severe cases

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The total chloride deficit is 5 to 15 mEq/kg.

Result

usually low

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The total body deficit of magnesium is usually 1 to 2 mEq/kg owing to increased magnesium loss from diuresis.

Result

usually low

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The total body calcium deficit is usually approximately 1 to 2 mEq/kg owing to increased calcium loss from diuresis.

Result

usually low

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The total body phosphate deficit is 3 to 7 mmol/kg owing to increased phosphate loss from diuresis.

Result

usually low

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Effective serum osmolality is calculated as: 2 (measured Na [mEq/L]) + (glucose [mg/dL])/18 = mOsm/kg.[1]

BUN concentration is not taken into account, because it is freely permeable and its accumulation does not change the osmotic gradient.[1][43]

Coma, if present, is most often due to hypernatremia rather than hyperglycemia.

Result

≥320 mOsm/kg

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Anion gap is calculated as (Na)-(Cl + HCO3) as mEq/L.[1]

Levels ≥10 to 12 mEq/L signify an anion gap acidosis (i.e., lactic or ketoacidosis).[1]

Result

variable; usually 7 to 9 mEq/L

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Serum lactate is >5 mmol/L in lactic acidosis.

Lactic acid levels can be elevated if concomitant lactic acidosis is present.[1]

Result

usually normal

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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.[42]

Result

arterial pH usually >7.30; arterial bicarbonate is >15 mEq/L

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Infection is the major precipitating factor occurring in 30% to 60% of patients. Urinary tract infections and pneumonia are reported most commonly.[1][9][2] 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

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Abnormalities may exist if underlying diseases, such as fatty liver or congestive heart failure, are present.

Result

usually normal

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Leukocytosis is present in hyperglycemic crises. However, leukocytosis >25,000 per microliter may indicate infection and requires further evaluations.[1]

Result

leukocytosis

Investigations to consider

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The most common infections that precipitate HHS are pneumonia and urinary tract infections.[1][9][2]

Result

variable compatible with pneumonia

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Used to identify precipitating cardiovascular diseases, such as myocardial infarction (MI), or if severe electrolyte abnormalities are present.[1]

Evidence of hypo- (U waves) or hyperkalemia (tall T waves) may be present.

Result

may show evidence of MI or hyperkalemia or hypokalemia

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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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If indicated clinically, further sepsis workup should be performed.[1][9]

Result

positive in the presence of infection

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