Alkaline phosphatase: reference interval transference from CALIPER to a pediatric Brazilian population

ABSTRACT Introduction: Interpreting laboratory tests requires reference intervals (RI) that may vary between different populations. For the diagnosis of hypophosphatasia (HPP), lower limits of alkaline phosphatase (ALP) levels must be determined. Objective: To transfer the RI findings for ALP obtained by the Canadian Laboratory Initiative in Pediatric Reference Intervals (CALIPER) in children and adolescents, adjusted for the Brazilian population. Methods: The ALP measures from 1690 subjects (aging from 1-18 years) were analyzed. The CALIPER subgroups and the Clinical and Laboratory Standards Institute (CLSI) guideline were used for validation. Inclusion criteria were patients with normal range of hepatic and renal function, bone metabolism, and blood counts. Exclusion criteria were hospitalization, low weight, and use of drugs that could interfere in the ALP measurement and patients in with more than three orders for ALP measuring test. The RI obtained were considered valid if more than 90% of patients were whitin of the CALIPER RI. Results: The ALP RI results (IU/l) obtained were: 149-301 for both sexes aged 1-9 years; 127-326 for both sexes aged 10-12 years; 62-212 for girls and 129-437 for boys aged 13-14 years; 52-120 for girls and 78-268 for boys aged 15-16 years; 45-97 for girls and 40-129 for boys aged 17-18 years. In 92.4% of the patients, the results were comparable with those of the CALIPER study. Conclusion: The results demonstrated that the ALP RI for Brazilian children and adolescents are comparable to the CALIPER study in 92.4% of the patients and can be used for this population.

摘要
引言：实验室检验结果的解读需依托参考区间（reference intervals, RI），不同人群的参考区间往往存在差异。针对低磷酸酯酶症（hypophosphatasia, HPP）的诊断，需明确碱性磷酸酶（alkaline phosphatase, ALP）水平的下限阈值。
研究目的：将加拿大儿童青少年参考区间实验室倡议（Canadian Laboratory Initiative in Pediatric Reference Intervals, CALIPER）所获得的碱性磷酸酶参考区间，针对巴西人群进行适配调整后开展迁移验证。
方法：本研究纳入1690名年龄1~18岁的受试者，对其碱性磷酸酶检测数据进行分析。采用CALIPER分组方案及美国临床和实验室标准协会（Clinical and Laboratory Standards Institute, CLSI）指南进行验证。纳入标准为肝肾功能、骨代谢及血常规指标均处于正常范围的患者；排除标准包括住院患者、体重过低者、使用可干扰碱性磷酸酶检测的药物者，以及碱性磷酸酶检测申请单超过3次的患者。若超过90%的受试者检测结果处于CALIPER参考区间范围内，则判定本次获得的参考区间有效。
结果：本次获得的碱性磷酸酶参考区间（单位：IU/l）如下：1~9岁男女受试者为149~301；10~12岁男女受试者为127~326；13~14岁女性受试者为62~212，男性受试者为129~437；15~16岁女性受试者为52~120，男性受试者为78~268；17~18岁女性受试者为45~97，男性受试者为40~129。92.4%的受试者检测结果与CALIPER研究结果具有可比性。
结论：本研究结果表明，92.4%的巴西儿童青少年的碱性磷酸酶检测结果与CALIPER研究参考区间相符，该参考区间可应用于巴西该人群的实验室检验解读。