仰卧位抽血诊断嗜铬细胞瘤和副神经节瘤(PPGL)的结果是血浆去甲肾上腺素的假阳性率低于坐位采样。目前尚不清楚住院患者与门诊测试以及其他分析前因素如何影响假阳性。
我们旨在确定分析前的预防措施,以最大程度地减少血浆间肾上腺素的假阳性结果。
评估了不同采血条件对血浆间肾上腺素的影响,包括门诊和住院测试,半卧位与完全卧位的血液采样,使用套管与直接静脉穿刺,和外界温度的差异。共有10个三级转诊中心的3147名患者接受了PPGL测试,包括278个有肿瘤和2869个没有肿瘤。分析假阳性结果的比率。
门诊而不是住院患者取样导致血浆浓度升高44%,去甲肾上腺素的假阳性结果增加3.4倍。低温,半卧位,与其他采样条件相比,直接静脉穿刺也导致血浆浓度和血浆去甲肾上腺素的假阳性结果率明显更高,尽管影响小于门诊抽样。与温暖的温度相比,血浆去甲肾上腺素的浓度较高和假阳性结果率仅在门诊采样时才明显。分析前因素对PPGL患者的血浆间肾上腺素没有影响。
虽然住院患者血液取样对于筛查疑似PPGL患者来说在很大程度上是不切实际的,其他分析前预防措施(例如,套管,温暖的测试条件)可能是有用的。住院患者采样可能会保留用于难以区分真实和假阳性结果的患者的随访。
Sampling of blood in the supine position for diagnosis of pheochromocytoma and paraganglioma (PPGL) results in lower rates of false positives for plasma normetanephrine than seated sampling. It is unclear how inpatient vs outpatient testing and other preanalytical factors impact false positives.
We aimed to identify preanalytical precautions to minimize false-positive results for plasma metanephrines.
Impacts of different blood sampling conditions on plasma metanephrines were evaluated, including outpatient vs inpatient testing, sampling of blood in semi- vs fully recumbent positions, use of cannulae vs direct venipuncture, and differences in outside temperature. A total of 3147 patients at 10 tertiary referral centers were tested for PPGL, including 278 with and 2869 without tumors. Rates of false-positive results were analyzed.
Outpatient rather than inpatient sampling resulted in 44% higher plasma concentrations and a 3.4-fold increase in false-positive results for normetanephrine. Low temperature, a semi-recumbent position, and direct venipuncture also resulted in significantly higher plasma concentrations and rates of false-positive results for plasma normetanephrine than alternative sampling conditions, although with less impact than outpatient sampling. Higher concentrations and rates of false-positive results for plasma normetanephrine with low compared with warm temperatures were only apparent for outpatient sampling. Preanalytical factors were without impact on plasma metanephrines in patients with PPGL.
Although inpatient blood sampling is largely impractical for screening patients with suspected PPGL, other preanalytical precautions (eg, cannulae, warm testing conditions) may be useful. Inpatient sampling may be reserved for follow-up of patients with difficult to distinguish true- from false-positive results.