Wat does kidney gritt mean?

Big crystals, sand?: Kidney grit and sand most likely are crystals in the urine. Some crystals form in normal urine if the urine is concentrated (not dilute), so has a high concentration of minerals. Other crystals are abnormal crystals that form and grow... And can turn into kidney stones if they get big enough. Abnormal concentrations of certain minerals can be related to one's diet, genetics, and water intake.

Crystals: Kidney grit is not a medial term, but probably implies crystals in urine. Drink enough water daily so that your urine is mostly colorless. Have a healthy diet, exercise 30 minutes/day, drink plenty of water, have safe sex, no tobacco alcohol weed or street drugs. For nutrition: http://www.choosemyplate.gov/.