Homogentisic Acid analysis using High-Performance Liquid Chromatography (HPLC) is a test used to determine the levels of this acid in biological samples, such as urine. This test is important in diagnosing "black urine disease" (Alkaptonuria), a genetic disorder that affects metabolism and leads to the accumulation of the acid in the body. Elevated levels of homogentisic acid can be a sign of underlying health issues, as it is associated with the development of symptoms such as joint pain and skin pigmentation. Due to its high accuracy, this test helps determine the need for therapeutic intervention and monitor the condition of patients.