Notar-Francesco V, Samuel S, Kanakamedala S, Straus E W
Department of Medicine, State University of New York (SUNY) Health Science Center at Brooklyn 11203-2098, USA.
J Assoc Acad Minor Phys. 1995;6(4):130-3.
Patients referred to us with "positive" secretin tests and the diagnosis of Zollinger-Ellison syndrome were found to be achlorhydric. This observation led us to study prospectively the accuracy and precision of serum gastrin determinations from commercial laboratories. Synthetic gastrin (G17) was added to serum to achieve gastrin concentrations of 50, 100, 250, 500, 750, 1000, 3000, and 5000 pg/mL after subtraction of the basal value (24 pg/mL). Three aliquots of each concentration were analyzed by radioimmunoassay in our laboratory (Health Science Center at Brooklyn) and sent to four major commercial laboratories that perform 5000 to 25,000 gastrin assays per year. The reported gastrin concentrations of the triplicate samples demonstrate that many commercial laboratories failed to accurately measure gastrin. Commercial laboratories generally reported higher-than-actual gastrin concentrations in samples containing less than 500 pg/mL and lower-than-actual gastrin concentrations in samples containing more than 500 pg/mL. Of all aliquots containing 100 pg/mL or less, 14 of 24 samples (58%) were reported by commercial laboratories to contain elevated gastrin concentrations. At gastrin concentrations from 250 to 5000 pg/mL, the range of values (highest- to lowest-reported value for each concentration) was greater than 200 pg/mL in 62% of triplicate samples reported by commercial laboratories. These data indicate that determinations by some commercial laboratories lack the precision required to satisfy the current diagnostic criterion (a postsecretin rise from basal gastrin of 200 pg/mL or greater) for Zollinger-Ellison syndrome. Clinicians should be aware of this problem and obtain more basal serum gastrin samples to allow for an analysis of the range of baseline values prior to secretin injection.
那些因“阳性”促胰液素试验而被转诊至我们这里并被诊断为卓-艾综合征的患者被发现无胃酸分泌。这一观察结果促使我们对商业实验室血清胃泌素测定的准确性和精密度进行前瞻性研究。在减去基础值（24 pg/mL）后，向血清中添加合成胃泌素（G17），以使胃泌素浓度达到50、100、250、500、750、1000、3000和5000 pg/mL。每种浓度的三个等分试样在我们实验室（布鲁克林健康科学中心）通过放射免疫测定法进行分析，并被送往四个主要的商业实验室，这些实验室每年进行5000至25000次胃泌素检测。对三份重复样本报告的胃泌素浓度表明，许多商业实验室未能准确测量胃泌素。商业实验室通常报告说，含有低于500 pg/mL的样本中胃泌素浓度高于实际值，而含有高于500 pg/mL的样本中胃泌素浓度低于实际值。在所有含有100 pg/mL或更低浓度的等分试样中，商业实验室报告称24个样本中有14个（58%）的胃泌素浓度升高。在胃泌素浓度为250至5000 pg/mL时，商业实验室报告的三份重复样本中，62%的样本值范围（每种浓度下报告的最高值与最低值）大于200 pg/mL。这些数据表明，一些商业实验室的测定缺乏满足当前卓-艾综合征诊断标准（促胰液素注射后基础胃泌素升高200 pg/mL或更高）所需的精密度。临床医生应意识到这个问题，并获取更多基础血清胃泌素样本，以便在注射促胰液素之前分析基线值范围。
