Institute of Clinical Genetics, University Hospital Carl Gustav Carus, Technische Universität Dresden, 01307 Dresden, Germany.
Department of Internal Medicine III, University Hospital Carl Gustav Carus, Technische Universität Dresden, 01307 Dresden, Germany.
J Clin Endocrinol Metab. 2022 Aug 18;107(9):e3689-e3698. doi: 10.1210/clinem/dgac390.
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.
卧位采血诊断嗜铬细胞瘤和副神经节瘤（PPGL）的血样中，血浆去甲变肾上腺素的假阳性率低于坐位采血。尚不清楚住院与门诊检测以及其他分析前因素如何影响假阳性率。
旨在确定分析前注意事项，以尽量减少血浆甲肾上腺素假阳性结果。
评估了不同采血条件对血浆甲肾上腺素的影响，包括门诊与住院检测、半卧位与全卧位采血、使用套管与直接静脉穿刺、以及外界温度的差异。10 个三级转诊中心的 3147 例患者接受了 PPGL 检测，其中 278 例有肿瘤，2869 例无肿瘤。分析了假阳性结果的发生率。
与住院相比，门诊采血导致血浆浓度升高 44%，假阳性率升高 3.4 倍。低温、半卧位和直接静脉穿刺也导致血浆去甲变肾上腺素浓度和假阳性率显著升高，尽管其影响小于门诊采血。仅在门诊采血时，低温与高温相比，血浆去甲变肾上腺素浓度和假阳性率更高。在有 PPGL 的患者中，分析前因素对血浆甲肾上腺素无影响。
尽管住院采血对疑似 PPGL 患者的筛查不太实际，但其他分析前注意事项（如套管、温暖的检测条件）可能有用。对于难以区分真性与假性阳性结果的患者，可保留住院采血用于随访。
