Occurs when the body is deprived of its normal supply of water or excessive water is lost. There is a delicate balance in the body between water and dissolved substances. This condition is most life-threatening in newborns, infants and persons over 60. Dehydration occurs when the body loses more fluids then it takes in. The loss of fluid can come from vomiting, diarrhea, sweating, or urination. Severe dehydration can lead to renal failure, and cardiovascular collapse.