About one in ten suffers from long-term consequences after being infected with the coronavirus. Despite the symptoms of Long Covid, normal laboratory tests often showed no abnormalities. Scientists from Innsbruck have now succeeded in discovering characteristic patterns in the urine samples of patients that cannot be found in healthy people.
About ten percent of people who have had Covid-19 subsequently suffer from persistent symptoms such as fatigue, fatigue, shortness of breath, chest, joint or muscle pain, sleep disturbances, cognitive impairment or impairment of their mental health,” Maya Taenzer recently wrote from the newspaper University Clinic for Internal Medicine II (MedUni Innsbruck) and their co-authors in the scientific journal “International Journal of Tryptophan Research”.
Easily researched biomarkers aid in diagnosis
Apparently, several causes of the disease are involved, mainly 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: Since routine tests in Long Covid patients are meaningless, there is an urgent need for easy-to-research biomarkers to be able to investigate the causes of the disease on the one hand, but also to find ways to provide personalized treatment to the those affected.
For laboratory medicine, urine samples remain the easiest way to access metabolic parameters. The scientists from Innsbruck therefore conducted a pilot study. Samples were examined from 25 people with Long Covid (including 20 women), from eight healthy controls (including seven women) and from eight people with so-called myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), which look similar to Long Covid can.
Since 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 the patients.”
Concentration of amino acids lower in 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 tryptophan and tyrosine metabolites, for example serotonin, dopamine and catecholamine, deviated from the reference values,” the scientists discovered. The neurotransmitters serotonin, dopamine or catecholamines are known to be involved in many neurological or psychological disorders.
Depending on the symptom, different amino acid concentrations
In any case, Long Covid patients who suffered from constant exhaustion and fatigue had lower concentrations of the amino acids kynurenine and phenylalanine. For example, in anxiety patients there was a lower concentration of gamma-aminobutyric acid (GABA). GABA is the major inhibitory neurotransmitter in the brain and an antagonist of excitatory glutamate. Several anti-seizure medications work by increasing GABA levels.
Biomarkers for personalized treatment strategies
In their study, the scientists draw the following conclusion from the laboratory results: “In summary, our results indicate that amino acid metabolism and neurotransmitter synthesis are disturbed in patients with Long Covid and ME/CFS. The identified degradation products and their dysregulation could serve as potential biomarkers for research into the causes of diseases and lead to personalized treatment strategies for these patient groups.”
Source: Krone
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