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Amino Acids, Urine

Urine amino acid testing is used to determine the adequacy of dietary proteins and the balance of amino acids in the body, factors that lurk in many chronic pathological conditions.

Amino acid testing shows the level of amino acids available in the body for the production of structural, transport, and storage proteins, the synthesis of immunoglobulins and enzymes. Amino acids also play an important role in many other body functions, such as the synthesis of neurotransmitters, the metabolism of carbohydrates and cholesterol, and the organism's detoxification processes.

Why is Amino Acid testing important?

Amino acid imbalance in the body can often be the first sign of many diseases, ranging from depression to obesity. Amino acid balance disorders and deficiencies are common in people with poor nutrition. Since stress, age, the presence of inflammation, and various other factors, including exercise, can affect amino acid levels, people with good nutrition may also have deficiencies.

Plasma and urine amino acid analysis is a useful diagnostic asset in the identification of inherited metabolic diseases (e.g., phenylketonuria) and in the examination of patients on chronic parenteral nutrition.

Amino acid balance disorders are observed in certain conditions of the gastrointestinal tract, food intolerances, vitamin and mineral deficiencies, renal and hepatic impairment with reduced ability to detoxify the body, in psychiatric disorders, in chronic inflammation and oxidative stress, and many other inherited and acquired disorders of amino acid metabolism.

Who should test for Amino Acids?

Amino acid testing can help patients investigating the causes of diseases such as:

  • Attention Deficit Hyperactivity Disorder (ADHD)
  • Autism spectrum disorders
  • Depression and stress
  • Epileptic seizures
  • Chronic fatigue syndrome
  • Insomnia
  • Cardiovascular diseases
  • Hypertension
  • Digestive disorders
  • Infertility (in men and women)
  • Nutritional deficiencies
  • Rheumatoid arthritis and other autoimmune diseases
More information

Amino acids are organic compounds that contain nitrogen and are the building blocks of proteins. More than 500 amino acids have been identified in nature, but only 22 are used in protein synthesis and only 20 are encoded by our genetic code in DNA. These 20 amino acids are classified as essential and non-essential. Essential amino acids cannot be synthesized by the human body and therefore must be included in the daily diet. Some amino acids are referred to as under conditions essential because they may be necessary under specific conditions, usually age or certain pathological conditions. For example, arginine can be synthesized by adults, but not by children.

Many important amino acids from those used in protein synthesis and also some of those not used in protein synthesis, play critical roles in the body. For example, in the human brain glutamic acid and gamma-amino-butyric acid (GABA) are the major stimulant and inhibitory neurotransmitters, respectively, hydroxyproline (an important component of connective tissue collagen) synthesized from the amino acid proline, glycine is used to synthesize porphyrins used in red blood cells and carnitine is used to transport lipids.

Many people have "hidden" disorders in amino acid metabolism that often go undiagnosed. These disorders can have specific symptoms and in many cases do not have any specific signs or symptoms and can increase a person's susceptibility to various degenerative diseases

Amino acid testing provides important information about nutritional adequacy, including the quality and quantity of dietary proteins, indirect information about digestive disorders and malabsorption syndromes, and also indirect information about deficiencies and the metabolism of vitamins and minerals. In addition, the amino acid analysis provides important diagnostic information regarding hepatic and renal function, the availability of neurotransmitter precursors, the ability to detoxify, and many inherited disorders of amino acid metabolism.

Plasma Amino Acids and Urine Amino Acids

Plasma amino acid analysis measures their levels at the time of sampling. The sample should be taken after a 12-hour fast to reduce the effect of dietary protein. Possible anomalies arise from the comparison of the measured levels with established reference values.

Urine amino acids analysis has a higher probability of detecting abnormalities if renal function is normal. The 24-hour sample collection detects amino acid levels throughout the day, reflects the levels and reserves of amino acids in the blood and tissues, and is not affected by the circadian (daily) rhythm. Normal kidney function effectively maintains essential amino acids in the body. Therefore, the levels of amino acids in the urine are affected earlier and give signs of deficiency before their plasma levels are even disturbed. The analysis of amino acids in the first-morning urine sample is an alternative when the complete collection of 24-hour urine is not possible.

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