The ELISA (enzyme-linked immunosorbent assay) is a test which uses color change and antibodies to identify a substance. An indirect ELISA is one of three ELISA tests.
Urine varies in appearance, depending principally upon a body's level of hydration, as well as other factors. Normal urine is a transparent solution ranging from colorless to amber but is usually a pale yellow. In the urine of a healthy individual the color comes primarily from the presence of urobilin.
Urine is made as a normal result of metabolism and removal of cellular wastes. Normal urine is sterile and the color can vary depending on what your pet has recently eaten or drunk. If youâre wondering why urine is yellow, itâs due to the presence of a substance called urochrome which is excreted by the kidneys.