Van Hoof V O, De Broe M E
Department of Clinical Chemistry, University Hospital Antwerp, Edegem/Antwerpen, Belgium.
Crit Rev Clin Lab Sci. 1994;31(3):197-293. doi: 10.3109/10408369409084677.
Alkaline phosphatase (ALP, EC 3.1.3.1) is a membrane-bound metalloenzyme that consists of a group of true isoenzymes, all glycoproteins, encoded for by at least four different gene loci: tissue-nonspecific, intestinal, placental, and germ-cell ALP. Through posttranslational modifications of the tissue-nonspecific gene, for example, through differences in carbohydrate composition, bone and liver ALP are formed. Nowadays, most commercially available methods for separating or measuring ALP isoenzymes are easy to perform and sensitive and allow for reproducible and quantitative results. As more isoenzymes and isoforms have been characterized, confusion has arisen due to the many different names they were given. For the sake of simplicity and because of structural analogies, we propose an alternative nomenclature for the ALP isoenzymes and isoforms based on their structural characteristics: soluble, dimeric (Sol), anchor-bearing (Anch), and membrane-bound (Mem) liver, bone, intestinal, and placental ALP. Together with lipoprotein-bound liver ALP and immunoglobulin-bound ALP, these names largely fit the many forms of ALP one can encounter in human serum and tissues. The clinically relevant isoenzymes are sol-liver, Mem-liver, lipoprotein-bound liver, and Sol-intestinal ALP in liver diseases, and Sol-bone and Anch-bone ALP in bone diseases. Many different isoenzyme patterns can be found in malignancies and renal diseases. This test provides the clinician with valuable information for diagnostic purposes as well as for follow-up of patients and monitoring of treatment. However, ALP isoenzyme determination will only provide clinically useful information if the patterns are correctly interpreted. In this respect, care should be taken to use the proper reference ranges, taking into account the age and sex of the patient. A normal total ALP activity does not rule out the presence of an abnormal isoenzyme pattern, particularly in children. Separating ALP into its isoenzymes adds considerable value to the mere assay of total ALP activity.
碱性磷酸酶（ALP，EC 3.1.3.1）是一种膜结合金属酶，由一组真正的同工酶组成，均为糖蛋白，由至少四个不同的基因位点编码：组织非特异性、肠道、胎盘和生殖细胞碱性磷酸酶。例如，通过对组织非特异性基因进行翻译后修饰，通过碳水化合物组成的差异，形成了骨和肝碱性磷酸酶。如今，大多数市售的分离或测量碱性磷酸酶同工酶的方法操作简便、灵敏，能得到可重复的定量结果。随着越来越多的同工酶和同工型被鉴定出来，由于它们被赋予了许多不同的名称，导致了混淆。为了简单起见，并基于结构上的相似性，我们根据其结构特征为碱性磷酸酶同工酶和同工型提出了一种替代命名法：可溶性二聚体（Sol）、带锚定基团（Anch）和膜结合（Mem）的肝、骨、肠道和胎盘碱性磷酸酶。连同脂蛋白结合的肝碱性磷酸酶和免疫球蛋白结合的碱性磷酸酶，这些名称在很大程度上适用于人们在人血清和组织中可能遇到的多种碱性磷酸酶形式。在肝脏疾病中，临床相关的同工酶是可溶性肝碱性磷酸酶、膜结合肝碱性磷酸酶、脂蛋白结合肝碱性磷酸酶和可溶性肠道碱性磷酸酶；在骨骼疾病中是可溶性骨碱性磷酸酶和带锚定基团骨碱性磷酸酶。在恶性肿瘤和肾脏疾病中可以发现许多不同的同工酶模式。该检测为临床医生提供了有价值的诊断信息，以及用于患者随访和治疗监测。然而，只有在正确解释模式的情况下，碱性磷酸酶同工酶测定才会提供临床有用的信息。在这方面，应注意使用适当的参考范围，并考虑患者的年龄和性别。正常的总碱性磷酸酶活性并不排除存在异常的同工酶模式，尤其是在儿童中。将碱性磷酸酶分离成其同工酶比单纯测定总碱性磷酸酶活性具有更大的价值。
