Eur J Endocrinol. 2014 Feb 4;170(3):349-57. doi: 10.1530/EJE-13-0673. Print 2014 Mar.
Higher plasma concentrations of catecholamines in winter than in summer have been established, but whether this impacts the plasma concentrations of metanephrines used for the diagnosis of pheochromocytoma is unknown.
In this study, we examined seasonal variations in the plasma concentrations of metanephrines, the impact of this on diagnostic test performance and the influences of forearm warming ('arterialization' of venous blood) on blood flow and measured concentrations.
The measurements of the plasma concentrations of metanephrines were recorded from 4052 patients tested for pheochromocytoma at two clinical centers. Among these patients, 107 had tumors. An additional 26 volunteers were enrolled for the measurements of plasma metanephrines and forearm blood flow before and after forearm warming.
There was no seasonal variation in the plasma concentrations of metanephrines among patients with pheochromocytoma, whereas among those without tumors, the plasma concentrations of normetanephrine were higher (P<0.0001) in winter than in summer. Lowest concentrations of normetanephrine were measured in July, with those recorded from December to April being more than 21% higher (P<0.0001). These differences resulted in a twofold higher (P=0.0012) prevalence of false-positive elevations of normetanephrine concentrations in winter than in summer, associated with a drop in overall diagnostic specificity from 96% in summer to 92% in winter (P=0.0010). Forearm warming increased blood flow and lowered (P=0.0020) plasma normetanephrine concentrations.
The plasma concentrations of normetanephrine are subject to seasonal variation with a resulting higher prevalence of false-positive results in winter than in summer. Lowered plasma concentrations of normetanephrine with forearm warming suggest an effect of temperature. These results have implications for considerations of temperature to minimize false-positive results.
已经证实，冬季血浆儿茶酚胺浓度高于夏季，但这是否会影响用于诊断嗜铬细胞瘤的间甲肾上腺素的血浆浓度尚不清楚。
本研究检测了间甲肾上腺素的血浆浓度的季节性变化，及其对诊断试验性能的影响，以及前臂加热（静脉血“动脉化”）对血流和测量浓度的影响。
从两个临床中心检测嗜铬细胞瘤的 4052 名患者中记录间甲肾上腺素的血浆浓度测量值。其中 107 名患者有肿瘤。另外招募了 26 名志愿者，在进行前臂加热前后测量血浆间甲肾上腺素和前臂血流量。
嗜铬细胞瘤患者的间甲肾上腺素血浆浓度无季节性变化，而无肿瘤患者的间甲肾上腺素浓度在冬季较高（P<0.0001）。7 月份间甲肾上腺素浓度最低，12 月至 4 月间记录的浓度比夏季高 21%以上（P<0.0001）。这些差异导致冬季假阳性间甲肾上腺素浓度升高的发生率比夏季高两倍（P=0.0012），总体诊断特异性从夏季的 96%下降到冬季的 92%（P=0.0010）。前臂加热增加了血流量并降低了（P=0.0020）间甲肾上腺素的血浆浓度。
间甲肾上腺素的血浆浓度存在季节性变化，导致冬季假阳性结果的发生率高于夏季。前臂加热降低了间甲肾上腺素的血浆浓度，提示温度的影响。这些结果对考虑降低温度以减少假阳性结果具有启示意义。
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