Abstract
This study serially measured the plasma Arginine Vasopressin (AVP) in 11 preterm infants who had umbilical arterial catheters placed at birth for blood gas measurements either for respiratory distress syndrome or immaturity such that ventilatory support was required. Plasma samples of 20-200 μl were taken 4-12 hourly for up to 100 hrs. after birth. Plasma AVP was measured by a cytochemical assay with a sensitivity of 2 femtograms per ml of plasma*. In only 4 infants was a significant correlation found between plasma AVP and plasma osmolality. The normal "resting" level of plasma AVP was between 0.5 and 2 pg/ml. In 4 infants apparent bursts of plasma AVP secretion were seen. These could not be correlated either with changes in arterial oxygen, blood pressure, or ventilator pressures - all of which were being monitored continuously or the frequently measured values of plasma sodium or osmolality or urine specific gravity. One spontaneously breathing infant with respiratory distress had continuous very high levels of plasma AVP (12-25 pg/ml) recorded over the 1st 100 hours of life and this was associated frequently with low plasma osmolality. This was obviously inappropriate secretion but the renal response was upset as there was continuous production of dilute urine! Serial measurements of plasma AVP proved possible and showed that contrary to previous evidence even the very preterm newborn is capable of producing high levels of this hormone. *Smith,A. & McIntosh,N. Bioscience Reports 1981 in press
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Mcintosh, N., Smith, A. Plasma Arginine Vasopress in measured serially in the preterm newborn. Pediatr Res 18, 799 (1984). https://doi.org/10.1203/00006450-198408000-00046
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DOI: https://doi.org/10.1203/00006450-198408000-00046