What is the purpose of a guiac specimen?

A guiac specimen is specifically designed to detect the presence of blood in stool. This test is based on a chemical reaction that occurs when hemoglobin, the protein in red blood cells, comes into contact with the guiac reagent, resulting in a color change. This method is commonly used in screening for gastrointestinal bleeding, which can indicate conditions such as hemorrhoids, ulcers, polyps, or colorectal cancer.

The other options relate to different tests: checking for blood in urine involves urinalysis; checking for infection may require cultures or other diagnostic methods; and testing for electrolytes typically involves blood tests rather than stool samples. Each of these processes utilizes specific methods and tests tailored to the substances being assessed.