If your urine is… Bright yellow. This may look alarming, especially when your urine seems to be glowing in the dark. But don’t worry — the bright yellow color is likely due to vitamins, specifically, B vitamins and beta carotene.
This is dehydration. You need to increase your fluid intake. Dark coloured urine is a strong indicator of low fluids, so increase your intake with water as opposed to softdrinks. Keep your kidneys flushed to avoid problems.
As everyone else has said it is probably de-hydration. Asparagus can do this to some degree to some people. Thought I would mention it given it is in season.