The simplest test used to diagnose this condition is the water deprivation test, which restricts oral fluids and observes changes urine volume and concentration. Normally, reducing fluids results concentrated urine diminished volume. In DI, fluid restriction has little or no effect on urine formation but causes weight loss from dehydration. Accurate results from this procedure require strict monitoring of fluid intake and urinary output, measurement of urine concentration (specific gravity osmolality), and weight checks. A weight loss between 3% and 5% indicates significant dehydration and requires termination of the fluid restriction.