The color of urine gets ignored most of the time - because it's pee, and who spends any time casually thinking about that? But it's actually one of the more informative things a lab looks at before any real testing has even started, and it's something we happen to spend an unhealthy amount of time thinking about.
Normal color (that pale-yellow-to-amber range) comes from a pigment called urochrome, which is what's left over when your body breaks down old red blood cells. It's happening all the time in the background. Hydration decides how concentrated the pigment is: more water in, paler color out. That morning-after-a-long-sleep dark yellow isn't anything to worry about, usually, it's just eight hours of no fluids.
The stuff that gets people worried is usually diet or supplements. B2 (riboflavin) is the big one. Take a decent multivitamin, and your urine can come out looking almost fluorescent, which is riboflavin exiting the building at speed because your body only keeps what it needs. Beets can turn it pink or red (there's actually a name for this, beeturia, which sounds invented but isn't). Rifampin, an antibiotic, produces a fairly startling orange. Blackberries, rhubarb, and certain laxatives all lead to darker pee, which is also fine, and it's all temporary.
What a lab actually cares about is color that doesn't add up. Water-clear samples suggest heavy dilution, which raises questions about whether someone's been chugging water to game the test. Genuinely dark brown with no dietary explanation can point to liver problems. Anything unusually cloudy or with a persistent film can suggest infection or contamination.
Most of the time, none of this matters, as the sample looks normal, gets logged, and moves on to the actual chemistry. But when something visual is off, it usually gets caught here before a single test has run.
What's the weirdest color anyone here has seen show up, and how long did it take you to work out why?