Urinalysis and Body Fluids 6th Edition by Majorie DiLorenzo, Susan Strasinger

Exercise 32

Discuss the principle of the sodium nitroprusside reaction to detect ketones, including sensitivity and possible causes of interference.

Step 1 of 3

Reagent strip test of ketone:

Principle: sodium nitroprusside reaction (nitroferricyanide) is used to detect ketones in urine.

• Acetoacetic acid (present in urine) and sodium nitroprusside (in reagent strip) in alkaline medium gives purple color.

• The test is not possible for beta-hydroxybutyrate measurement and also marginally sensitive to acetone.

• As these compounds are produced from acetoacetic acid, their presence is supposed in the test.

• Results are given as negative trace 1+ (small),2+ (moderate),3+ (large),or reported as semi quantitatively 5 mg /dL (milligram per deciliter) (trace),15 mg/dL (small),40 mg/dL (moderate) and 80 to 160 mg/dL (large).