Transtyretin som biomarkör för nutritionsstatus vid utredning för kolorektalcancer
Sammanfattning: Title:Transthyretin as a biomarker for nutritional status during investigation for colorectal cancerCourse:MED730, Research thesis in Clinical Nutrition, 30 ECTSLevel:Second CycleSemester/year:St 2017Supervisor:Frode Slinde och Alexandra VulcanExaminer:Heléne Bertéus ForslundKeywords:Transthyretin, biomarker, nutritional status, colorectal, cancer, malnutrition, body composition, energy, protein, FFMIBackground:Malnutrition is common in colorectal cancer, as well as loss of muscle mass without concurrent major weight loss. Assessment of nutritional status may thus be misleading, with a risk of overlooking malnourished individuals. Biomarkers, such as transthyretin, may be a helpful alternative, when measuring body composition can not be applied. There is however no clear answer to whether it is a good measure of nutritional status in cancer.Objective:The aim was to investigate whether plasma levels of transthyretin can be used as a biomarker for energy and protein intake, as well as for nutritional status regarding the proportion of fat free mass in individuals undergoing investigation for colorectal cancer.Methods:A cross-sectional study was conducted with 15 individuals undergoing investigation for colorectal cancer. Data was collected regarding energy and protein intake, body composition (bioelectric impedance spectroscopy) and plasma levels of transthyretin and CRP. Malnutrition was assessed using ESPEN's diagnostic criteria. The relationship between transthyretin and CRP, intake of energy and protein, fat-free mass index, FFMI, and malnutrition were analyzed via linear regression and Fischer’s exact test.Results:No connection with transthyretin was detected for either protein intake or malnutrition. A significant negative association was observed between transthyretin and energy intake (p = 0,03). A tendency towards significance was noticed between transthyretin and FFMI (p = 0,059). A significant negative association was found between CRP and transthyretin (p = 0,03). Subgroup analysis with CRP < 15 mg/l showed a significant relationship between transthyretin and malnutrition (p = 0,03) as well as FFMI (p < 0,001). The connection between change in transthyretin over time and energy intake was also significant when subjects with CRP > 15 mg/l were excluded from the analysis (p = 0,008). A tendency towards a significant association was also seen regarding protein intake (p = 0,052).Conclusion:Transthyretin may be a useful biomarker for nutritional status, defined as FFMI, in colorectal cancer. In conditions without inflammation, transthyretin may also be helpful to assess occurrence of malnutrition and to determine whether the intake of energy and protein is adequate. However, at CRP > 15 mg/l, transthyretin should not be used as a marker for neither malnutrition nor nutritional intake. Since there is a strong correlation between CRP and transthyretin, the presence of inflammation should always be examined in order for a correct interpretation of transthyretin to be possible.
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