I have never drunk my own urine; nor do i think i ever will. But this was practiced alot in the past, esp abroad. My mom as a young child was made to do so by her great-aunts and they (great-aunts) died at 96 and 94. So the practice obviously wasn't harmful. I think it's just another old time remedy, like smearing your head with cow manure to cure baldness, eating raw liver to cure anemia, using baking soda to clean teeth (which btw does help bleach teeth)...
Here's some more info I found:
In alternative medicine, the term urine therapy (also urotherapy, urinotherapy or uropathy) refers to various applications of human urine for medicinal or cosmetic purposes, including drinking of one's own urine and massaging one's skin with one's own urine. While there are no known scientifically proven health benefits of such therapeutic use for urine, some chemical components of urine do have some well known commercial and other uses, like urea and urokinase. For instance, urea in urine has been found to be antibacterial to bacteria causing urinary tract infections specifically, and ingestion of urea has been found to increase this antibacterial activity in urine itself, though no evidence was found for such an effect upon the actual ingestion or application of urine.
Urine's main constituents are water and urea; the latter of which has some well-known commercial and other uses. Urine also contains small quantities of thousands of compounds, hormones and metabolites, including corticosteroids. Pregnant mare's urine has high amounts of estrogens, which are isolated and sold as Premarin.
Urine and urea have been claimed by some practitioners to have an anti-cancer effect. It has been hypothesized that because some cancer cell antigens are transferred through urine, through "oral autourotherapy" these antigens could be introduced to the immune system that might then create antibodies. However, the American Cancer Society's position is that scientific evidence does not support individual claims that urine or urea given in any form is helpful for cancer patients, and that the safety of urine therapy has not been confirmed by scientific studies
Drinking one's morning urine ('amaroli') was an ancient yoga practise designed to promote meditation. The ancient Hindu and yoga texts that mention auto-urine drinking, require it be done before sunrise and that only the mid-stream sample be used. The pineal hormone melatonin and its conjugated esters are present in morning urine in significant quantities, the pineal gland secreting melatonin maximally at about 2 am, this secretion being shut off by the eyes' exposure to bright sunlight. Melatonin, when ingested or given intravenously, amongst other effects, provokes tranquility and heightened visualisation. There are high concentrations of melatonin in the first morning urine, but not in a physiologically active form.