Selenium levels in colorectal cancer: A systematic review and meta-analysis of serum, plasma, and colorectal specimens.

BACKGROUND: Colorectal cancer (CRC) is a growing public health problem. Several clinical studies have shown a potentially protective effect of selenium (Se), but the reports are inconsistent. The objective of the study was to examine the evidence for relation between serum/tissue Se status and CRC. METHOD AND MATERIALS: In this Systematic Review and Meta-Analysis, we searched Cochrane Library, EBSCOhost, EMBASE, ProQuest, PubMed/MEDLINE, Scopus, and Web of Science for studies reporting serum/plasma/whole blood/tissue Se concentrations in CRC patients and controls for articles published till August 2023. Meta-analysis was performed, and study quality, heterogeneity, and small study effects were assessed. Based on a random effects model, summary mean differences in serum levels of Se between CRC patients and healthy controls, and Se levels between malignant and matched non-malignant tissue specimens were assessed. RESULTS: After initial screening, a total of 24 studies (18 serum and 6 tissue studies) with a pooled total of 2640 participants were included in the meta-analysis. CRC patients had significantly lower serum Se levels than healthy controls, being the difference between the two equal to 3.73 µg/dl (95% CI: 6.85-0.61). However, the heterogeneity was very high, I2= 99% (p < 0.01). Our meta-analysis showed higher Se levels in CRC cancerous specimens than in matched healthy colon tissue: the increase was equal to 0.07 µg/g wet tissue weight (95% CI: 0.06-0.09; p= 0.02). CONCLUSIONS: CRC patients have lower serum and higher colon cancerous tissue Se levels. Some factors, such as Se levels in different tumor grades of CRC need to be further considered for a more conclusive association between Se levels and risk of CRC.

Comparative Evaluation of Serum Lithium Estimation Using Plain Glass Vial and Serum Clot Activator Vacutainer by Reflectance Photometry.

Introduction The collection of blood samples in different vacutainers can affect the result of serum lithium estimation due to the presence of distinct additives in the blood collection vacutainer for enhancing the clot formation process. Due to the low therapeutic index and threat of toxicity of lithium, it is imperative to correctly report the test result. Thus, it has become a challenge for the laboratory physician to estimate lithium in any clinical laboratory setup. Materials and Methods Sample of 100 patients were collected and paired into clot activator vacutainers and plain glass vials. After centrifugation, samples from the paired collection tubes were processed immediately for serum lithium estimation by VITROS 4600 analyzer working on the principle of reflectance photometry. Both the paired tubes were stored at 2 to 8°C and were further analyzed, at 24 and 48 hours, respectively, from the time of their collection. The statistical analysis was done in IBM SPSS software version 23. Results There was a statistically significant differences between the mean of lithium values when processed within 1st hour of collection, obtained from clot activator vacutainers in comparison to glass vials. However, within tube comparison, there was no statistical difference in the lithium values estimated at 1st hour, 24 hours, and 48 hours of collection. Conclusion In this study, lithium values measured by clot-activated vacutainers are found to be lower as compared with values measured through glass vials.