A-134 Comparative Analysis of ALT and AST Measurements: Impact of P5P Activators on Platform Discrepancies
Authors: Li X 
Published: October 2024

Abstract

Background
Vitamin B6 (VB6), notably its active form pyridoxal 5'-phosphate (P5P or PLP), is essential for ALT and AST enzyme activity in amino acid metabolism. Insufficient P5P can yield inaccurately low ALT and AST measurements in individuals with VB6 deficiency. This study assesses VB6 deficiency prevalence and its impact on ALT and AST measurements on Beckman Coulter compared to Roche and Siemens platforms.

Methods
VB6 levels were analyzed in 996 patients, with &lt; 20 nmol/L considered deficient. ALT and AST levels were compared between Beckman Coulter AU5800 versus Roche cobas c, and Beckman Coulter AU5800 versus Siemens Dimension Vista. Roche and Siemens assays included P5P supplements, while Beckman Coulter did not. 29 ALT specimens (23 VB6 deficient and 6 normal) and 34 AST specimens (28 VB6 deficient and 6 normal) were compared between Beckman Coulter and Roche. Additionally, 16 specimens (4 VB6 deficient and 12 normal) were tested for ALT and AST for the comparison between Beckman Coulter and Siemens. The study then assessed the impact of P5P-containing reagents on test results by comparing the percentage differences in average concentration and their clinical decision implications across different platforms, within the low, normal, and high ranges.

Results
Out of 996 patients, 356 exhibited VB6 results below 20 nmol/L, indicating a striking 36% prevalence of VB6 deficiency within our patient population. Beckman Coulter and Roche comparison: In VB6 deficient patients, ALT displayed an average concentration difference of 11.5%: Beckman ALT mean 23 (+/-24.6) U/L versus Roche ALT mean 26 (+/-30) U/L. AST demonstrated a 41% difference in average concentration: Beckman AST mean 28.2 (+/-28.9) U/L versus Roche AST 48.9 (+/-49) U/L. In normal patients, ALT displayed an average concentration difference of 2.4%: Beckman ALT mean 21.3 (+/-21.3) U/L versus Roche ALT mean 20.8 (+/-25.7) U/L. AST demonstrated a 23.5% difference in average concentration: Beckman AST mean 25.5. (+/-25.4) U/L versus Roche AST 33.3 (+/-37.5) U/L. Additionally, 13% of ALT and 18% of AST displayed noteworthy effects on clinical decisions, resulting in shifts from low abnormal to normal range or normal range to high abnormal. Beckman Coulter and Siemens comparison: In VB6 deficient patients, ALT displayed an average concentration difference of 36.8%: Beckman ALT mean 18 (+/-15.7) U/L versus Siemens ALT mean 28.5 (+/-20.5) U/L. AST demonstrated a 43.4% difference in average concentration: Beckman AST mean 18.3 (+/-8.1) U/L versus Siemens AST 32.3 (+/-17.2) U/L. In normal patients, ALT displayed an average concentration difference of 32.8%: Beckman ALT mean 22.2 (+/-16.1) U/L versus Siemens ALT mean 33.1 (+/-20.1) U/L. AST demonstrated a 31.3% difference in average concentration: Beckman AST mean 25.4 (+/-12.3) U/L versus Siemens AST 36.1 (+/-19.7) U/L. While 6% of ALT specimens would have altered clinical decisions, the impact was more pronounced for AST, with 50% of results changing to an upper reference point.

Conclusions
In clinical settings where accurate assessment of enzyme activity is vital for effective patient care, our study emphasizes the crucial necessity for standardizing AST and ALT methodologies to incorporate P5P supplementation.