It is possible to tell the difference between male and female urine. Though urine is mostly water, it also contains elements like sodium, calcium and magnesium and compounds like fatty acids, carbohydrates and hormones.
The tiny amounts of hormones that are excreted in urine are what allow chemists to tell whether the donor is male or female. It is the hormones in urine, for example, that make home pregnancy tests possible. The hormones in the urine of pregnant mares, or premarin, is used to ease the symptoms of menopause in human females. The urine of women who have gone through menopause can be used for fertility treatments.