2024-01-03 04:35:11
A significant proportion of people who have had Sars-CoV-2 disease later develop Long Covid symptoms. Normal laboratory tests often show no abnormalities. Innsbruck scientists have now discovered characteristic patterns in urine samples from those affected that were not found in healthy people.
“Around ten percent of people who have had Covid-19 subsequently suffer from persistent symptoms such as fatigue, fatigue, breathlessness, chest, joint or muscle pain, sleep disorders, cognitive disorders or impaired mental health,” Maya recently wrote Taenzer from the University Clinic for Internal Medicine II (MedUni Innsbruck) and her co-authors in the scientific journal “International Journal of Tryptophan Research”.
Apparently, different causes of the disease are involved, especially inflammatory reactions and changes in amino acid metabolism, in the functioning of the autonomic nervous system and the intestinal tract. The problem, according to the experts: Because routine tests in Long Covid patients are not meaningful, there is an urgent need for easily examined biomarkers in order to be able to investigate the causes of the clinical picture on the one hand, but also to find ways to provide personalized treatment for those affected.
For laboratory medicine, urine samples continue to be the easiest way to access metabolic parameters. The Innsbruck scientists therefore carried out a pilot study. Samples were examined from 25 people with Long Covid (including 20 women), from eight healthy control subjects (including seven women) and from eight people with so-called myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), which have an appearance similar to Long Covid can.
Because many symptoms of Long Covid are likely to have something to do with the brain or nervous system, the authors of the scientific work focused on certain proteins in the urine samples. “The concentrations of neurotransmitter precursor proteins such as tryptophan, phenylalanine and their metabolites were examined, as well as their association with symptoms (fatigue, anxiety and depression) of patients.”
An important first result: The concentration of the essential amino acid phenylalanine was significantly lower in the subjects with Long Covid and those affected by ME/CFS than in the control group. “In many Long Covid patients, the concentration of the metabolites of tryptophan and tyrosine, for example serotonin, dopamine and catecholamine, deviated from the reference values,” the scientists found. The neurotransmitters serotonin, dopamine or catecholamines are known to be involved in many neurological or psychological disorders.
In any case, Long Covid patients who suffered from constant exhaustion and fatigue had lower concentrations of the amino acids kynurenine and phenylalanine. In patients with anxiety, for example, there was a lower concentration of gamma-aminobutyric acid (GABA). GABA is the most important inhibitory neurotransmitter in the brain and an antagonist to the excitatory glutamate. Various anti-epilepsy drugs work by increasing GABA levels.
In their study, the scientists draw, among other things, the following conclusion from the laboratory results: “In summary, our results indicate that the amino acid metabolism and the synthesis of neurotransmitters are disturbed in patients with Long Covid and ME/CFS. The identified degradation products and their dysregulation might serve as potential biomarkers for research into the causes of disease and lead to personalized treatment strategies for these patient groups.”
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