Raum W J, Swerdloff R S
Clin Chem. 1981 Jan;27(1):43-7.
A radioimmunoassay involving an 125I ligand has been developed and applied to the measurement of urinary metanephrine. To validate the clinical usefulness of this assay, we compared measurement of metanephrine by radioimmunoassay and of total urinary metanephrines by the Pisano colorimetric method. The radioimmunoassay is specific for metanephrine, whereas the colorimetric method measures both metanephrine and normetanephrine. We used both methods to determine urinary metanephrine or total metanephrines in subjects with essential hypertension, pheochromocytoma, the syndrome of multiple endocrine adenomatosis type 2, and normotensive volunteers. The mean and upper limit of normal (3 SD) for metanephrine by radioimmunoassay in our normotensive volunteers was 94.2 microgram/24 h and 229 microgram/24 h, respectively, which compares well with reported values of 87.6 microgram/24 h and 319 microgram/24 h by non-radioimmunoassay methods. Both radioimmunoassay and colorimetry accurately identified five patients with known pheochromocytoma. Good correlation (r = 0.993) was demonstrated between the two assays in a comparison of patients with essential hypertension and pheochromocytoma. We conclude that the radioimmunoassay is at least equivalent to the colorimetric methods in distinguishing pathological and normal catecholamine secretion, and is faster, more precise, and 1000-fold more sensitive.
一种涉及¹²⁵I配体的放射免疫分析法已被开发出来，并应用于尿间甲肾上腺素的测定。为了验证该分析方法的临床实用性，我们比较了放射免疫分析法测定间甲肾上腺素和皮萨诺比色法测定尿总间甲肾上腺素的结果。放射免疫分析法对间甲肾上腺素具有特异性，而比色法可同时测定间甲肾上腺素和去甲间肾上腺素。我们使用这两种方法来测定原发性高血压患者、嗜铬细胞瘤患者、2型多发性内分泌腺瘤综合征患者以及血压正常的志愿者的尿间甲肾上腺素或尿总间甲肾上腺素。在我们的血压正常的志愿者中，放射免疫分析法测定间甲肾上腺素的平均值和正常上限（3个标准差）分别为94.2微克/24小时和229微克/24小时，这与非放射免疫分析方法报告的87.6微克/24小时和319微克/24小时的值相当。放射免疫分析法和比色法都准确地识别出了5名已知患有嗜铬细胞瘤的患者。在对原发性高血压患者和嗜铬细胞瘤患者的比较中，两种分析方法之间显示出良好的相关性（r = 0.993）。我们得出结论，在区分病理性和正常儿茶酚胺分泌方面，放射免疫分析法至少与比色法相当，而且更快、更精确，灵敏度高出1000倍。
