[Objective] To conduct a retrospective statistical comparison of alanine aminotransferase (ALT) test values in blood donors prior to blood collection, aiming to analyze the objective characteristics of the population with elevated ALT levels (ALT>50 U/L) and provide reference data for adjusting the screening eligibility threshold for ALT. [Methods] The preliminary ALT screening data of 30 341 blood donor samples collected prior to blood donation from three smart blood donation sites at the Shenzhen Blood Center between 2022 and 2023 were extracted and compared with data from a health examination department of a tertiary hospital in Shenzhen (representing the general population, n=24 906). Both datasets were categorized and statistically described. A retrospective analysis was conducted to examine the associations between ALT test results and factors such as donors' gender, age, ethnicity, donation site, donation season, and frequency of blood donation. [Results] The ALT levels in both blood donors and the general population were non-normally distributed. The 95th percentile of ALT values was calculated as 61.4 U/L (male: 67.8 U/L, female: 39.3 U/L) for blood donors and 58.1 U/L (male: 63.7 U/L, female: 51.2 U/L) for the general population. The non-compliance rates (ALT>50 U/L) were 7.65% (2 321/30 341) in blood donors and 7.08% (1 763/24 906) in the general population. There were significant differences (P<0.05) in the ALT failure rate among blood donors based on gender, age, and donation site, but no significant differences (P>0.05) during the blood donation season. There was no statistically significant difference (P>0.05) in the positive rates of four serological markers (HBsAg, anti HCV, HIV Ag/Ab, anti TP) for blood screening pathogens between ALT unqualified and qualified individuals (2.05% vs 1.5%). If the ALT qualification threshold was raised from 50 U/L to 90 U/L, the non qualification rates of male and female blood donors would decrease from 9.82% (2 074/21 125) to 2.23% (471/21 125) and from 2.70% (249/9 216) to 0.75% (69/9 216), respectively. Among the 154 blood donors who donated blood more than 3 times, 88.31% of the 248 ALT test results were in the range of 50-90 U/L. Among them, 9 cases had ALT>130 U/L, and ALT was converted to qualified in subsequent blood donations. [Conclusion] There are differences in the ALT failure rate among blood donors of different genders and ages, and different blood donation sites and operators can also affect the ALT detection values of blood donors. The vast majority of blood donors with ALT failure are caused by transient and non pathological factors. With the widespread use of blood virus nucleic acid testing, appropriately increasing the ALT qualification threshold for blood donors can expand the qualified population and alleviate the shortage of blood sources, and the risk of blood safety will not increase.

Objective: To comprehensively evaluate the current alanine aminotransferase (ALT) screening strategies and provide a basis for their optimization. Methods: ALT test results of 21 345 blood samples were collected from 33 blood collection institutions. Multiple probability distribution functions were employed to fit the data, and the akaike information criterion (AIC) was used to determine the optimal fitting model. Based on this model, 1 million random samplings were conducted to simulate the final ALT test results of blood donors under different ALT screening strategies, eligibility criteria, and pre-donation ALT detection deviations. A decision tree was subsequently constructed for health economic analysis. Results: The log-normal distribution with a mean of 2.96 and a variance of 0.65 provided the best fit for the data. When the eligibility criteria was 50 U/L and the pre-donation detection deviation was ±20%, not conducting pre-donation testing increased blood donation by 1.14%. When the pre-donation detection deviation was ±20% and the eligibility criteria was raised from 50 U/L to 100 U/L, conducting and not conducting pre-donation testing increased blood donation by 7.59% and 6.60%, respectively. With a eligibility criteria of 50 U/L and a pre-donation detection deviation of ±20%, 1.14% of eligible blood donors would be disqualified from donating blood. Health economic analysis showed that when the eligibility criteria was adjusted to 56 U/L or higher, not conducting pre-donation ALT testing was the dominant strategy; under other conditions, conducting pre-donation testing was the dominant strategy. Conclusion: The selection of ALT testing strategies is a complex process influenced by multiple factors, and it is necessary to adopt an appropriate ALT screening strategy based on specific testing circumstances.