An infant's urine contains 500 mg/dL galactose and no glucose. Which of the following test results would be obtained?

• A. Negative on stix, trace Clinitest
• B. Negative on stix, 500 mg/dL Clinitest
• C. 500 mg/dL on stix, trace Clinitest
• D. 500 mg/dL on stix, 500 mg/dL on Clinitest

Answer: (B)

The main idea here is how these tests detect sugars in urine. The dipstick (stix) test for glucose uses a glucose-specific reaction, so it will be negative when only galactose is present. Galactose isn’t detected by that test, even if it’s in substantial amount. The Clinitest, on the other hand, is a reducing-sugar test based on a copper reduction reaction; it detects any reducing sugar, including galactose, and reports a semiquantitative result (in this case, a reading corresponding to 500 mg/dL).

So with 500 mg/dL of galactose and no glucose:

• The dipstick would be negative because there’s no glucose to react.

• The Clinitest would be positive at a level around 500 mg/dL because galactose is a reducing sugar and would reduce copper in the test, yielding a positive result.

That pattern aligns with choosing the option that shows a negative dipstick and a positive Clinitest at 500 mg/dL. The other patterns would imply glucose on the dipstick or a weak/trace Clinitest, which doesn’t fit the given scenario of galactosuria without glucosuria.