Fluid deprivation test

A fluid deprivation test is a medical test for the purposes of diagnosing the causes of polydipsia, a condition of excessive thirst that causes an excessive intake of water. The patient is required, for a prolonged period, to forgo intake of water completely, to determine whether thirst is caused by:
 * 1) excessive intake of fluid
 * 2) a defect in ADH production
 * 3) a defect in the kidneys' response to ADH production

This test measures changes in body weight, urine output, and urine composition when fluids are withheld. Sometimes measuring blood levels of ADH during this test is also necessary.