Alkaline phosphatase isoenzymes in children with respiratory disease

Slavica Dodig,Zaneta Jelcic,Darko Richter,Jadranka Demirovic,Ivana Cepelak,Miljenko Raos,Nina Perusko Matasic,Kornelija Kovac,Rajka Petrinovic

doi:10.11613/bm.2007.011

Abstract

Aim: To present the electrophoretic pattern of alkaline phosphatase (ALP) isoenzymes in serum of infants and children exhibiting increased total ALP catalytic activity in the course of acute respiratory disease. Subjects and methods: Results obtained in 21 children (17 of them infants), including 13 male and eight female children aged 2 months to 8 years, hospitalized for respiratory diseases are presented. Total ALP catalytic activity was determined and electrophoretic separation of ALP isoenzymes was performed in children's sera. Results: Increased total ALP catalytic activity (range, 528-5622 U/L) during hospital stay was recorded in eight (38.1%) children. A typical picture of be-nign transient hyperphosphatasemia (TH), which implies the occurrence of fast anodal fraction (faster than hepatic fraction) and near-cathode fraction (faster than bone fraction), was recorded in five children. The placental-like isoenzyme was detected in two children. Expression of bone fraction and placental-like fraction was recorded in a rachitic child. Prehepatic ALP was expressed in two children, and hepatic ALP isoenzyme in one child. Conclusion: Acute respiratory disease in infants and children may entail transient increase in the ALP catalytic activity with the occurrence of various isoenzyme bands such as fast anodal and near-cathode fraction (in TH), prehepatic fraction and placental-like fraction. TH is verified when total ALP activity has decreased and returned to reference intervals. In this case, no additional testing is required.

Highlights

Alkaline phosphatase, orthophosphate-phosphohydrolase (ALP; EC 3.1.3.1) is a common term for a group of glycosylated enzymes with optimal activity in the alkaline range
Transient hyperphosphatasemia (TH) in infants and children is a benign increase in the catalytic activity of serum ALP, which may persist for several weeks (2)
As transient hyperphosphatasemia (TH) may occur in children with respiratory diseases (2), the aim of the study was to show the electrophoretic pattern of ALP isoenzymes in serum of children exhibiting an increased total ALP catalytic activity in the course of acute respiratory disease

Summary

Introduction

Orthophosphate-phosphohydrolase (ALP; EC 3.1.3.1) is a common term for a group of glycosylated enzymes (isoenzymes) with optimal activity in the alkaline range (pH 9.8–10.5). The catalytic activity of ALP undergoes modification in childhood due to bone growth; it is moderately increased in the first three months of life, while in puberty it is two- to three-fold that in adults. Transient hyperphosphatasemia (TH) in infants and children is a benign increase in the catalytic activity of serum ALP, which may persist for several weeks (2). TH was first described in 1954 (3) As these children show no clinical signs of a bone or liver metabolic disease (4), TH is detected incidentally, on routine laboratory work-up. As TH may occur in children with respiratory diseases (2), the aim of the study was to show the electrophoretic pattern of ALP isoenzymes in serum of children exhibiting an increased total ALP catalytic activity in the course of acute respiratory disease

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