Ming Zuo1, Qianna Zhen2, Xiaoqing Zhang1, Wenbi Zou1, Xiangchun Yang1, Gang Tian1, Zhenghu Shi1, Qifu Li2, Min Ding3. 1. Key Laboratory of Clinical Laboratory Diagnostics, Ministry of Education, College of Laboratory Medicine, Chongqing Medical University, Chongqing 400016, PR China. 2. Department of Endocrinology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, PR China. 3. Key Laboratory of Clinical Laboratory Diagnostics, Ministry of Education, College of Laboratory Medicine, Chongqing Medical University, Chongqing 400016, PR China. Electronic address: dingmin@cqmu.edu.cn.
Abstract
BACKGROUND: The metanephrines (MNs) in plasma and urine were proposed as biomarkers for the diagnosis of pheochromocytomas and paragangliomas (PPGLs). However, plasma free MNs and 24h urinary fractionated MNs were not satisfactory enough in specificity for the diagnosis of PPGLs. Moreover, the collection of 24h urine was inconvenient. This work examined the diagnostic and prognostic efficiency of free MNs in spot urine for PPGLs. METHODS: We measured free MNs concentration in spot urine and plasma of 28 PPGLs patients and 155 control subjects by HPLC with electrochemical detection. Postoperative free MNs levels in spot urine and plasma of 14 PPGLs patients were also determined. Creatinine (Cr) concentration was used for the correction of urine volume. RESULTS: The specificity of spot urinary free MNs/Cr in the diagnosis of PPGLs was significantly higher than that of plasma free MNs [normetanephrine (NMN), 98.7% (95.4%-99.8%) vs 93.0% (87.4%-96.6%); metanephrine (MN), 93.6% (88.5%-96.9%) vs 84.5% (77.5%-90.0%)]. Meanwhile, the positive likelihood ratios for spot urinary free NMN/Cr and MN/Cr were 69.21 and 13.29, compared with 12.68 and 5.30 for plasma free NMN and MN, respectively. For the PPGLs patients underwent surgery, the plasma free MNs level appeared an abnormal elevation and yielded false-positive results for some patients. Our findings were validated in an independent cohort, resulting in the specificity of 100% for both urinary free NMN/Cr and MN/Cr, and 97.3% and 83.8% for plasma free NMN and MN, respectively. CONCLUSIONS: Spot urinary free MNs/Cr, superior to plasma free MNs, presented a promising biomarker for the diagnosis and prognosis of PPGLs.
BACKGROUND: The metanephrines (MNs) in plasma and urine were proposed as biomarkers for the diagnosis of pheochromocytomas and paragangliomas (PPGLs). However, plasma free MNs and 24h urinary fractionated MNs were not satisfactory enough in specificity for the diagnosis of PPGLs. Moreover, the collection of 24h urine was inconvenient. This work examined the diagnostic and prognostic efficiency of free MNs in spot urine for PPGLs. METHODS: We measured free MNs concentration in spot urine and plasma of 28 PPGLspatients and 155 control subjects by HPLC with electrochemical detection. Postoperative free MNs levels in spot urine and plasma of 14 PPGLspatients were also determined. Creatinine (Cr) concentration was used for the correction of urine volume. RESULTS: The specificity of spot urinary free MNs/Cr in the diagnosis of PPGLs was significantly higher than that of plasma free MNs [normetanephrine (NMN), 98.7% (95.4%-99.8%) vs 93.0% (87.4%-96.6%); metanephrine (MN), 93.6% (88.5%-96.9%) vs 84.5% (77.5%-90.0%)]. Meanwhile, the positive likelihood ratios for spot urinary free NMN/Cr and MN/Cr were 69.21 and 13.29, compared with 12.68 and 5.30 for plasma free NMN and MN, respectively. For the PPGLspatients underwent surgery, the plasma free MNs level appeared an abnormal elevation and yielded false-positive results for some patients. Our findings were validated in an independent cohort, resulting in the specificity of 100% for both urinary free NMN/Cr and MN/Cr, and 97.3% and 83.8% for plasma free NMN and MN, respectively. CONCLUSIONS: Spot urinary free MNs/Cr, superior to plasma free MNs, presented a promising biomarker for the diagnosis and prognosis of PPGLs.