Evaluation of serum bone alkaline phosphatase activity in patients with liver disease: Comparison between electrophoresis and chemiluminescent enzyme immunoassay

• Bone alkaline phosphatase (ALP) is a marker of bone formation and metabolism.
• Bone ALP was measured by electrophoresis & chemiluminescent enzyme immunoassay.
• When ALP3 isozyme predominated, the two methods showed good correlation.
• From ALP3 (%) < 23, correlation between the two methods deteriorated.
• In some special cases, the accuracy of the electrophoresis is questionable.

BackgroundSerum bone alkaline phosphatase (ALP) is a marker of bone formation and metabolism. However, existing methods for measuring it have their limitations and their accuracy has not been determined.MethodsWe measured serum bone ALP activity in 127 patients with liver disease using 2 methods: electrophoresis and chemiluminescent enzyme immunoassay (CLEIA). The results of these 2 methods were compared and analyzed according to gender, age and several serum biochemical markers.ResultsWhen ALP3 (%; bone-type isozyme activity as a percentage of total ALP activity) values were high, the 2 methods showed good correlation. However, with a decrease in ALP3 (%) levels, the correlation coefficient (R) also decreased. Starting with ALP3 (%) < 23, R values markedly decreased to < 0.50 (p > 0.05). Five outliers displayed low ALP3 (%) activity levels. Furthermore, in regard to genders, there were significant differences in total cholesterol (TC), γ-glutamyltransferase (γ-GTP), ALP and ALP3 (%) levels (p < 0.05).ConclusionsWhen serum ALP3 (%) levels were high in patients with liver disease, the accuracy of electrophoresis was comparable to that of CLEIA. However, the accuracy of electrophoresis needs to be evaluated with further when patient samples under certain conditions.