The release of antidiuretic hormone is appropriate in response to hypovolemia and/or sodium administration in children with severe head injury: A trial of lactated Ringer's solution versus hypertonic saline

We conducted an open, randomized, and prospective study to determine the ef fect of hypertonic saline on the secretion of antidiuretic hormone (ADH) an d aldosterone in children with severe head injury (Glasgow coma scale <8). Thirty-one consecutive patients at a level III pediatric intensive care uni t at a children's hospital received either lactated Ringer's solution (Ring er's group, n = 16) or hypertonic saline (Hypertonic Saline group, n = 15) over a 3-day period. Serum ADH levels were significantly larger in the Hype rtonic Saline group as compared with the Ringer's group (P = 0.001; analysi s of variance) and were correlated to sodium intake (Ringer's group: r = 0. 39, R-2 = 0.15, P = 0.02; Hypertonic Saline group: r = 0.42, R-2 = 0.18, P = 0.02) and volume of fluids given IV (Ringer's group: r = 0.38, R-2 = 0.15 , P = 0.02; Hypertonic Saline group: r = 0.32, R-2 = 0.1, P = not significa nt). Correlation of ADH to plasma osmolality was significant if plasma osmo lality was >280 mOsm/kg (r = 0.5, R-2 = 0.25, P = 0.06), indicating an osmo tic threshold for ADH release. Serum aldosterone levels were larger on the first day than during Days 2 and 3 in both groups and inversely correlated to serum sodium levels only in the Ringer's group (r = - 0.55, R-2 = 0.3, P < 0.001). This group received a significantly larger fluid volume on Day 1 (P = 0.05, Mann-Whitney U-test) than did patients in the Hypertonic Saline group, indicating hypovolemia during the first day. Head-injured children have appropriate levels of ADH. They may be hypovolemic during the first da y of treatment, especially if they receive lactated Ringer's solution.