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Selected Publication:
Wenninger, J.
Possible links between iron and tryptophan metabolism in individuals with iron deficiency and anaemia.
Doktoratsstudium der Medizinischen Wissenschaft; Humanmedizin; [ Dissertation ] Graz Medical University; 2020. pp. 112
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- Authors Med Uni Graz:
- Advisor:
- Enko Dietmar
- Meinitzer Andreas
- Windpassinger Christian
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- Abstract:
- In our study, we evaluated potential associations of tryptophan, kynurenine, and kynurenic acid with indicators of iron metabolism (i.e., mean corpuscular volume, mean corpuscular haemoglobin, ferritin, transferrin saturation, serum iron, transferrin, soluble transferrin receptor, reticulocyte haemoglobin) and haemoglobin in 430 individuals grouped by the presence or absence of iron deficiency or anaemia. All study participants, which were included in this cross-sectional study provided their written informed consent. They were admitted for a medical check-up of their actual iron status and underwent venous blood sampling after an overnight fasting state in the morning (between 8.00 and 10.00 a.m.). The samples were used to investigate the iron metabolism (i.e., haemoglobin, mean corpuscular volume, mean corpuscular haemoglobin, ferritin, transferrin saturation, serum iron, transferrin, soluble transferrin receptor, reticulocyte haemoglobin), the tryptophan metabolism (tryptophan, kynurenine, kynurenic acid, kynurenine/tryptophan ratio, kynurenic acid/kynurenine index), the renal function (creatinine, estimated glomerular filtration rate [eGFR]), and the C-reactive protein. Indicators of tryptophan metabolism were positively correlated with haemoglobin and markers of iron metabolism (p-values: <0.001 – 0.038; r-values: 0.100 – 0.305). The strongest correlation was observed between tryptophan and haemoglobin (p < 0.001, r = 0.305). The cubic regression model yielded the highest R-square values between haemoglobin and tryptophan markers. Overall, 115 patients with iron deficiency showed lower tryptophan and kynurenic acid concentrations compared to 315 individuals without iron deficiency. Six patients with anaemia of chronic disease were observed with the lowest serum tryptophan levels and the highest kynurenine/tryptophan ratio compared to 11 individuals with iron deficiency anaemia and 413 non-anaemic patients. This study showed little to moderate associations between haemoglobin, biomarkers of iron metabolism and tryptophan markers. Further studies are needed to get better insight in the causality of these findings.