1991 年 38 巻 5 号 p. 451-456
We present here the results of water restriction test (WRT) and hypertonic saline loading test (HSLT) in normal children. Maximal urine osmolality during WRT (W-Umax; 1040±154mOsm/kg) may be age-dependent (W-Umax=812+23age, r=0.52, p<0.05), although maximal arginine vasopressin (AVP) levels during WRT did not show any correlation with age. The relationship between plasma osmolality (Posm) and AVP during HSLT in children (AVP=0.31(Posm-277)) was similar to that in normal adults. A plateau urine osmolality during HSLT (H-Umax) was 713±109mOsm/kg. It did not increase with age. AVP levels 3 h after the infusion did not correlate with age. Minimal AVP and Posm values (about 6pg/ml, 295mOsm/kg, respectively) for creating H-Umax apparently existed during HSLT. The minimal AVP value (about 6pg/ml) for H-Umax (during HSLT) was higher than the AVP levels (2.41±1.37pg/ml) at W-Umax (during WRT). W-Umax (1040±154mOsm/kg) was significantly higher than H-Umax (713±109 mOsm/kg). Judging from the above comparison of AVP and Uosm (W, H-Umax) at the plateau state of WRT and HSLT in normal children, a change in the apparent tubular response to AVP may be one of the important factors to maintain circulatory volume (CV).
