Lab Med Online.  2017 Jul;7(3):128-134. 10.3343/lmo.2017.7.3.128.

Effects of Pyridoxal-5'-Phosphate on Aminotransferase Activity Assay

• Lee JS
• Lee K
• Kim SM
• Choi MS
• Jun SH
• Song WH
• Song SH
• Park KU
• Song J

• KMID: 2383091
• DOI: http://doi.org/10.3343/lmo.2017.7.3.128

Abstract

BACKGROUND
Pyridoxal-5'-phosphate (P5P), a coenzyme of the aspartate aminotransferase (AST) and alanine aminotransferase (ALT) reactions, is required to measure aminotransferase levels (IFCC method). However, a modified IFCC method that uses a reagent devoid of P5P is commonly used in laboratories in Korea. To determine the differences between the two methods, we compared aminotransferase levels measured by using the IFCC method and modified IFCC method.
METHODS
Serum levels of AST and ALT, with and without P5P, were measured in 2,318 patients. Based on the allowable limits of performance set by the Royal College of Pathologists of Australasia (RCPA), differences between the two methods were analyzed under various conditions.
RESULTS
Higher AST and ALT values were obtained by the IFCC method compared to modified IFCC method, showing significant differences between the two methods (AST, 5.8±14.2 IU/L; ALT, 2.8±6.9 IU/L) (P<0.001). Values exceeding RCPA criteria were more frequently observed in emergency orders (AST, 65.8%; ALT, 14.4%) than in routine orders (AST, 3.2%; ALT, 9.6%), as well as in inpatient wards (AST, 70.4%; ALT, 18.5%) compared to outpatient clinics (AST, 56.6%; ALT, 10.0%). However, the differences between the two methods were not significant among the disease groups, except for the acute myocardial infarction group.
CONCLUSIONS
The method using reagents without P5P underestimated aminotransferase activity. The effect of P5P was more significant in patients with acute myocardial infarction, considered as P5P-deficient. In conclusion, the IFCC method with P5P should be applied for measuring AST and ALT serum levels.

Keyword

Liver function tests; Alanine aminotransferases; Aspartate aminotransferases; Pyridoxal phosphate

MeSH Terms

Alanine Transaminase
Ambulatory Care Facilities
Aspartate Aminotransferases
Australasia
Emergencies
Humans
Indicators and Reagents
Inpatients
Korea
Liver Function Tests
Methods
Myocardial Infarction
Pyridoxal Phosphate
Alanine Transaminase
Aspartate Aminotransferases
Indicators and Reagents
Pyridoxal Phosphate

Figure

• 

  Fig. 1. Bland-Altman plots for AST (IU/L) (A and B) and ALT (IU/L) (C and D) performed as emergency tests. Red lines represent allowable limits of performance.

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  Fig. 2. Bland-Altman plots for AST (IU/L) (A and B) and ALT (IU/L) (C and D) performed as routine tests. Red lines represent allowable limits of performance.

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