Final answer:
A 'port wine' colored urine specimen indicates the need to test for hemoglobinuria, which occurs when hemoglobin is present in the urine and oxidizes upon exposure to air.
Step-by-step explanation:
A urine specimen developing a "port wine" color while standing at room temperature should be tested for hemoglobinuria. Hemoglobinuria is characterized by the presence of hemoglobin in the urine without the presence of red blood cells (RBCs). It can occur in certain conditions such as hemolytic anemia, where red blood cells are destroyed in the bloodstream, or in cases with severe burns, infections, or malaria. The "port wine" color develops due to the oxidation of the hemoglobin when the urine is exposed to air over time. Hematuria, on the other hand, involves both RBCs and white blood cells (WBCs), and is observed in conditions such as nephritis or kidney stones. Myoglobinuria involves the presence of myoglobin and can occur in muscle damage. Bilirubinuria indicates the presence of bilirubin, often associated with liver disease or bile duct obstructions.