In what condition might you observe red-colored urine?

Red-colored urine can be observed in cases of porphyrias, which are a group of disorders caused by the accumulation of porphyrins due to abnormal heme production. In conditions like acute intermittent porphyria, patients may experience elevated levels of porphyrins that can cause the urine to appear reddish or dark. The red color is due to the presence of these compounds, which can be excreted in the urine during episodes of the disease.

In contrast, hematuria, another possible cause of red urine, typically signifies the presence of blood in the urine, which would also result in a red coloration but is a distinctly different condition. Dehydration may cause urine to become more concentrated, resulting in darker urine but not specifically red. Mononucleosis is associated with various symptoms and may lead to changes in urine but is not specifically known for causing red-colored urine. Therefore, porphyrias is the most fitting answer in the context of conditions that cause red urine.