Vasopressin serum levels and disorders of sodium and water balance in patients with severe brain injury

background: disorders of water and sodium balance are frequently seen in patients with severe brain injury (sbi), and may worsen their prognosis. purpose: to evaluate vasopressin (avp) serum levels and sodium and water balance disorders during the first week post-injury in patients with sbi. method: thirty-six adult patients with sbi (admission glasgow coma scale score < 8) and an estimated time of injury < 72 hours were prospectively studied. clinical and laboratory data were recorded and avp was measured in venous blood samples collected on the 1st, 2nd, 3rd and 5th days following inclusion. results: avp serum levels remained within the normal range in sbi patients (either traumatic or non-traumatic), although tended to be greater in non-survivor than in survivor patients (p=0.025 at 3rd day). in-hospital mortality was 43% (15/36), and serum sodium and plasma osmolality variabilities were greater in non-survivor than in survivor patients during the observation period (p<0.001). conclusion: avp serum levels remained within the normal range values in these sbi patients, but those who died have shown higher incidence of abnormal sodium and water balance during the first week post-injury.