Metzger D L, Wright N M, Veldhuis J D, Rogol A D, Kerrigan J R
Department of Pediatrics, University of Virginia Health Sciences Center, Charlottesville 22908.
J Clin Endocrinol Metab. 1993 Aug;77(2):458-63. doi: 10.1210/jcem.77.2.8345052.
Pulsatile secretion of cortisol (F) has not been documented in the newborn infant. Using repeated blood sampling and deconvolution analysis, we investigated F secretion and elimination dynamics in a group of five premature (gestational age, 24-34 weeks) and five term neonates. These infants had required placement of an umbilical arterial cannula for monitoring respiratory status, but were otherwise clinically stable. Blood samples were obtained at 15-min intervals for a 6-h period. All plasma F determinations were 58 nmol/L (2.1 micrograms/dL) or more, and pulsatile F secretion was observed in all infants. No significant differences were noted between the two groups with regard to 6-h mean plasma F concentration [350 +/- 129 (premature) vs. 277 +/- 54 nmol/L (term)], plasma corticosteroid-binding globulin (14 +/- 0 vs. 13 +/- 1 mg/L), F secretory burst frequency (4 +/- 0 vs. 5 +/- 1 bursts/6 h), mass of F secreted per burst [760 +/- 480 vs. 310 +/- 100 nmol/Lv [Lv, liter of F distribution volume)], F production rate (FPR; 2.7 +/- 1.4 vs. 1.1 +/- 0.2 mumol/Lv.6 h), or plasma F half-life (45 +/- 6 vs. 56 +/- 4 min). However, the premature infants had a significantly longer F secretory burst half-duration (63 +/- 18 vs. 6.7 +/- 4.0 min; P < 0.01) and a significantly lower maximal F secretory rate (9.4 +/- 3.4 vs. 100 +/- 26 nmol/Lv.min; P < 0.02) than the term infants. Body surface area and body weight were inversely correlated with F secretory burst half-duration (r = -0.74 and -0.75, respectively); both were also positively correlated with the maximal F secretory rate (r = 0.66 and 0.72). The two most premature infants had significantly greater mean plasma F and FPR than the other three premature and all of the term infants. Extrapolating to 24 h and correcting for the distribution volume of F and body surface area, we estimate FPR to be approximately 17-24 mumol/m2.24 h (6.6-8.8 mg/m2.24 h) for newborn infants of 34 weeks or more gestational age. These values are consistent with newer estimates of FPR in older children and adults determined using either deconvolution analysis or stable isotope dilution methods.
新生儿中尚未有皮质醇（F）脉冲式分泌的相关记录。我们通过重复采血和解卷积分析，对5名早产儿（胎龄24 - 34周）和5名足月儿的F分泌及清除动力学进行了研究。这些婴儿因监测呼吸状态需要放置脐动脉插管，但在其他方面临床状况稳定。在6小时内每隔15分钟采集一次血样。所有血浆F测定值均为58 nmol/L（2.1微克/分升）或更高，且在所有婴儿中均观察到了F的脉冲式分泌。两组在6小时平均血浆F浓度[350±129（早产）对277±54 nmol/L（足月）]、血浆皮质类固醇结合球蛋白（14±0对13±1 mg/L）、F分泌突发频率（4±0对5±1次突发/6小时）、每次突发分泌的F量[760±480对310±100 nmol/Lv[Lv，F分布容积升]]、F产生率（FPR；2.7±1.4对1.1±0.2 μmol/Lv.6小时）或血浆F半衰期（45±6对56±4分钟）方面均未观察到显著差异。然而，早产儿的F分泌突发半衰期明显更长（63±18对6.7±4.0分钟；P<0.01），最大F分泌率明显更低（9.4±3.4对100±26 nmol/Lv.min；P<0.02）。体表面积和体重与F分泌突发半衰期呈负相关（r分别为 - 0.74和 - 0.75）；两者也与最大F分泌率呈正相关（r分别为 = 0.66和0.72）。两名最早产的婴儿的平均血浆F和FPR明显高于其他三名早产儿及所有足月儿。外推至2小时并校正F的分布容积和体表面积后，我们估计胎龄34周或以上的新生儿FPR约为17 - 24 μmol/m².24小时（6.6 - 8.8 mg/m².24小时）。这些值与使用解卷积分析或稳定同位素稀释法确定的较大儿童和成人FPR的最新估计值一致。
