What does urinalysis show in Diabetic Ketoacidosis (DKA)?

Urinalysis in Diabetic Ketoacidosis

In DKA, urinalysis shows positive ketones (specifically acetoacetate and acetone) and glucose, but critically, standard urine dipsticks miss beta-hydroxybutyrate—the predominant ketone body in DKA—making urine ketone testing useful for screening but inadequate for diagnosis or monitoring treatment. 1, 2

What Urinalysis Detects in DKA

Ketones (Ketonuria)

• Urine dipsticks detect acetoacetate and acetone only using the nitroprusside reaction, which produces a purple color 1, 2
• The nitroprusside method is much more sensitive to acetoacetate than acetone and does not measure beta-hydroxybutyrate (bOHB), which is the predominant and strongest acid in DKA 1, 2
• This creates a significant limitation: urine testing underestimates total ketone body concentration because it misses the most abundant ketone 1, 3

Glucose (Glucosuria)

• Hyperglycemia exceeds the renal threshold, resulting in glucose spillage into urine 4, 5
• Combination dipsticks measuring both glucose and ketones are widely available 1

Clinical Utility and Limitations

Screening Value

• Positive urine ketones have high sensitivity and negative predictive value for DKA, making them useful for ruling out DKA in diabetic patients 2
• The presence of positive urine ketones in a diabetic with hyperglycemia and typical symptoms suggests impending or established DKA 1, 2

Critical Diagnostic Limitations

• Diagnosis of DKA should not rely on urine ketone determinations alone but requires hyperglycemia, increased blood ketone bodies or bOHB, and acidosis with increased anion gap 1
• As DKA resolves with treatment, beta-hydroxybutyrate is oxidized to acetoacetate, which means urine ketones may paradoxically increase even as DKA is resolving 6
• This lag phenomenon makes urine ketones unreliable for monitoring treatment response 1, 6

False Results

• False-positive results can occur with highly colored urine or sulfhydryl drugs like captopril 7, 3
• False-negative results occur with prolonged air exposure of test strips or highly acidic urine 3

Recommended Testing Approach

For Diagnosis

• Blood beta-hydroxybutyrate measurement is the preferred method for diagnosing DKA, as it directly measures the predominant ketone body 1, 2, 3
• If bOHB measurements are not readily available, increased blood ketones by nitroprusside reaction combined with hyperglycemia and metabolic acidosis can confirm DKA 1

For Monitoring Treatment

• Blood ketone determinations using the nitroprusside reaction should not be used to monitor DKA treatment because acetoacetate and acetone may increase as bOHB falls during successful therapy 1
• Resolution of acidosis or reduction in blood bOHB is the traditional marker for successful treatment 1
• DKA is resolved when glucose is <200 mg/dL, serum bicarbonate ≥18 mEq/L, and venous pH ≥7.3 2

Common Pitfalls to Avoid

• Do not use urine ketones to monitor DKA treatment—they lag behind clinical improvement and can be misleading 1, 6
• Do not exclude DKA based on normal glucose levels alone, especially in patients on SGLT2 inhibitors who can develop euglycemic DKA 1, 5, 8
• Do not assume negative urine ketones rule out ketosis—up to 30% of first morning urine specimens during starvation show positive ketones, and other conditions like alcoholic ketoacidosis also cause ketonuria 1, 7