Urine
Neurotransmitter supplementation
Urine test for levels of neurotransmitters: serotonin, GABA, glutamate, glycine, and glutamic acid.
€ 249,00
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Vitamins, minerals and amino acids · Urine
Glutamic acid (urine)
An amino acid that also acts as a messenger substance in the brain; in urine, the value depends on diet and storage.
At a glance
- Measured in urine
- In 2 test panels
- Check the preparation
Explanation
Glutamic acid (urine): what is measured?
This test measures glutamic acid (glutamate) in the urine, usually relative to creatinine to correct for how concentrated the urine is. Glutamic acid is an amino acid that the body makes itself and that is also found in food, including as a flavor enhancer (E621). In the brain, glutamate acts as a messenger substance, but the amount in urine says nothing about that. Normally the kidneys take back most amino acids from the primary urine, so only a small amount ends up in the urine. A sample that spends a long time in transit without cooling can give a higher value, because the glutamine in it is converted into glutamic acid.
What can it detect?
- A snapshot of glutamic acid excretion, which mainly reflects recent diet and supplements
- Sometimes a clue that the kidneys take back amino acids less well, which can only be assessed together with other amino acids and kidney values
- Rarely: an inborn disorder in the metabolism or transport of amino acids
Result
What does the result mean?
Glutamic acid (urine) too high
In adults without symptoms, a raised value of an amino acid is usually caused by a protein-rich meal or a protein shake shortly before the sample collection, by supplements containing amino acids (such as BCAAs, glutamine, arginine or taurine), or by the blood not being processed quickly enough. Reduced kidney function, liver disease, poorly controlled diabetes and some medicines can also raise values. A single, slightly raised value usually has no significance and causes no symptoms. Rarely, a strongly raised value, especially together with abnormalities in related amino acids, fits an inborn metabolic disease.
Glutamic acid (urine) too low
A low value is often caused by fasting, a low-protein meal, strenuous exercise or normal fluctuations during the day. Eating little or little protein for a long time, malnutrition, serious illness and pregnancy can lower several amino acids at once. A low value of one amino acid does not mean you need that amino acid as a supplement. Rarely, a low value fits an inborn disorder in the production of an amino acid.
After an abnormal result
A slightly abnormal value in someone without symptoms usually does not lead to further tests; the GP looks at diet, supplements, medicines and the circumstances of the sample collection, and has the test repeated while fasting if needed. With strongly abnormal values or an abnormal pattern together with matching symptoms, the GP consults, or refers you to, an internist (specialist in internal medicine) or pediatrician with experience in metabolic diseases.
Reliability
How reliable is the test?
In the Netherlands, amino acids are mainly measured in specialized laboratories for metabolic diseases, at the request of a specialist when an inborn metabolic disease is suspected or to monitor its treatment and diet. According to the American laboratory standard (ACMG), blood plasma, preferably collected while fasting, is the recommended sample; urine is less reliable as a first test, because the kidneys take back most amino acids and medicines can interfere with the measurement. As a 'functional' profile for finding deficiencies or tailoring supplements in adults without symptoms, the test has not been validated.
What can affect the result?
- Food, especially a protein-rich meal, and supplements shortly before the sample collection shift the values strongly; a fasting sample gives a more reliable picture.
- Blood must be centrifuged quickly and kept cool or frozen; otherwise some amino acids break down (including glutamine) or are released from blood cells. With home sample collection or shipping, this is a real risk.
- Time of day, exercise, age, pregnancy, kidney function and medicines (such as some epilepsy medicines) affect the result.
- Laboratories use different methods and reference values; results from different laboratories are hard to compare.
Preparation
- After getting up, first pass urine into the toilet as usual, then collect the second morning urine.
- You may have breakfast, but drink no more than 1 glass of water and no coffee before the second urine.
- Avoid caffeine, nicotine and alcohol for 2 days beforehand.
- Do not exercise in the 8 hours before collecting the sample.
- Do you take medication? Then check with your doctor.
- Do not collect urine during your period.
Who it is for
Who is the test useful for?
Useful for
In hospitals, a specialist uses this test when a metabolic disorder is specifically suspected, or to monitor a known metabolic disease and the diet that goes with it. For adults without symptoms, to find nutritional deficiencies or to choose supplements, the test is not useful according to current knowledge. If you use protein supplements or single amino acids, you get a result that mainly shows that intake.
How common is it?
Inborn disorders of amino acid metabolism are rare. In the Netherlands, the heel prick finds on average about 12 children with PKU (phenylketonuria) per year and about 1 child with MSUD (maple syrup urine disease) or tyrosinemia type 1. There are no Dutch figures on abnormal amino acid values in adults without symptoms.
RIVM, heel prick screening (pns.nl)
Get tested
Glutamic acid (urine): test panels
Glutamic acid (urine) is part of these test panels. You order online and have your blood drawn at a collection point or collect the sample at home.
Evidence
Sources
This explanation is based on Dutch guidelines and independent information. It is general information, not a diagnosis. Discuss an abnormal result with your GP.
More about risks and resultsMore explanations
Other tests: Vitamins, minerals and amino acids
- AC/FC ratio
- Acylcarnitine
- Alanine
- Antibodies against intrinsic factor
- Arginine
- Calcium
- Calcium (albumin-corrected)
- Carnitine, free
- Carnitine, total
- Coenzyme Q10
- Copper
- Folic acid