Deficient ADH from the posterior pituitary results in diabetes insipidus. This can be caused by head trauma; water is not conserved by the body, and excess amounts of urine are produced. Although increased serum glucose may cause polyuria, it is associated with diabetes mellitus, not diabetes insipidus. Ineffective renal perfusion will cause decreased urine production. While excess amounts of IV fluids may cause dilute urine, it is unlikely that a client with head trauma will be receiving excess fluid because of the danger of increased intracranial pressure.