el-Hajj Fuleihan G, Klerman E B, Brown E N, Choe Y, Brown E M, Czeisler C A
Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston Massachusetts 02115, USA.
J Clin Endocrinol Metab. 1997 Jan;82(1):281-6. doi: 10.1210/jcem.82.1.3683.
While circulating levels of PTH follow a diurnal pattern, it has been unclear whether these changes are truly endogenous or are dictated by external factors that themselves follow a diurnal pattern, such as sleep-wake cycles, light-dark cycles, meals, or posture. We evaluated the diurnal rhythm of PTH in 11 normal healthy male volunteers in our Intensive Physiologic Monitoring Unit. The first 36 h spent under baseline conditions were followed by 28-40 h of constant routine conditions (CR; enforced wakefulness in the strict semirecumbent position, with the consumption of hourly snacks). During baseline conditions, PTH levels followed a bimodal diurnal rhythm with an average amplitude of 4.2 pg/mL. A primary peak (t1max) occurred at 0314 h, and the secondary peak (t2max) occurred at 1726 h, whereas the primary and secondary nadirs (t1min and t2min) took place, on the average, at 1041 and 2103 h, respectively. This rhythm was preserved under CR conditions, albeit with different characteristics, thus confirming its endogenous nature. The serum ionized calcium (Cai) demonstrated a rhythm in 3 of the 5 subjects studied that varied widely between individuals and did not have any apparent relation to PTH. Urinary calcium/creatinine (UCa/Cr), phosphate/Cr (UPO4/Cr), and sodium/Cr (UNa/Cr) ratios all followed a diurnal rhythm during the baseline day. These rhythms persisted during the CR, although with different characteristics for the first two parameters, whereas that of UNa/Cr was unchanged. In general, the temporal pattern for the UCa/Cr curve was a mirror image of the PTH curve, whereas the UPO4/Cr pattern moved in parallel with the PTH curve. In conclusion, PTH levels exhibit a diurnal rhythm that persists during a CR, thereby confirming that a large component of this rhythm is an endogenous circadian rhythm. The clinical relevance of this rhythm is reflected in the associated rhythms of biological markers of PTH effect at the kidney, namely UCa/Cr and UPO4/Cr.
虽然甲状旁腺激素（PTH）的循环水平呈现昼夜节律模式，但尚不清楚这些变化是真正内源性的，还是由本身遵循昼夜节律模式的外部因素所决定，如睡眠-觉醒周期、明暗周期、饮食或姿势。我们在重症生理监测病房对11名正常健康男性志愿者的PTH昼夜节律进行了评估。在基线条件下度过的前36小时之后，是28 - 40小时的持续常规条件（CR；严格半卧位强制清醒，每小时食用点心）。在基线条件下，PTH水平呈现双峰昼夜节律，平均振幅为4.2 pg/mL。第一个峰值（t1max）出现在0314时，第二个峰值（t2max）出现在1726时，而第一个和第二个谷值（t1min和t2min）平均分别出现在1041时和2103时。尽管具有不同特征，但这种节律在CR条件下得以保留，从而证实了其内在性质。在所研究的5名受试者中，有3名受试者的血清离子钙（Cai）呈现出一种节律，个体之间差异很大，且与PTH没有明显关系。在基线日，尿钙/肌酐（UCa/Cr）、磷酸盐/肌酐（UPO4/Cr）和钠/肌酐（UNa/Cr）比值均呈现昼夜节律。这些节律在CR期间持续存在，尽管前两个参数具有不同特征，而UNa/Cr的节律没有变化。一般来说，UCa/Cr曲线的时间模式与PTH曲线呈镜像关系，而UPO4/Cr模式与PTH曲线平行移动。总之，PTH水平呈现昼夜节律，在CR期间持续存在，从而证实这种节律的很大一部分是内源性昼夜节律。这种节律的临床相关性体现在肾脏中PTH效应的生物学标志物（即UCa/Cr和UPO4/Cr）的相关节律中。
