Definition

Aminoaciduria is an abnormally high amount of amino acids in the urine. Amino acids are the building blocks for proteins in the body.

Alternative Names

Amino acids - urine; Urine amino acids

How the Test is Performed

A clean-catch urine sample may be needed. This is often done at your health care provider's office or health clinic.

How to Prepare for the Test

Most of the time, you do not need to take special steps before this test. Make sure your provider knows all of the medicines you recently used. If this test is being done on an infant who is breastfeeding, make sure the provider knows what medicines the nursing mother is taking.

How the Test will Feel

The test involves only normal urination.

Why the Test is Performed

This test is done to measure amino acid levels in the urine. There are many different types of amino acids. It is common for some of each kind to be found in the urine. Increased levels of individual amino acids can be a sign of a problem with metabolism.

Normal Results

The specific value is measured in µmol/g creatinine. The values below represent normal ranges in 24 hours urine for adults. In children, normal values vary with age. In addition, normal values may vary between different laboratories. Talk to your provider about your specific test results.

Alanine: 78 to 1337

Arginine: 5 to 70

Asparagine: 25 to 454

Aspartic acid: 1 to 87

Citrulline: 1 to 27

Cystine: 0 to 224

Glutamic acid: 5 to 92

Glutamine: 5 to 1756

Glycine: 277 to 7997

Histidine: 106 to 2534

Isoleucine: 5 to 48

Leucine: 5 to 129

Lysine: 15 to 1021

Methionine: 1 to 37

Ornithine: 5 to 76

Phenylalanine: 5 to 239

Proline: 5 to 169

Serine: 98 to 1053

Taurine: 24 to 5336

Threonine: 5 to 715

Tyrosine: 5 to 389

Valine: 5 to 147

The examples above show the common measurements for results for these tests. Some laboratories use different measurements or may test different specimens.

What Abnormal Results Mean

Increased total urine amino acids may be due to:

• Alkaptonuria
• Canavan disease
• Cystinosis
• Cystathioninuria
• Fructose intolerance
• Galactosemia
• Hartnup disease
• Homocystinuria
• Hyperammonemia
• Hyperparathyroidism
• Maple syrup urine disease
• Methylmalonic acidemia
• Multiple myeloma
• Ornithine transcarbamylase deficiency
• Osteomalacia
• Propionic acidemia
• Rickets
• Tyrosinemia type 1
• Tyrosinemia type 2
• Viral hepatitis
• Wilson disease

Considerations

Screening infants for increased levels of amino acids can help detect problems with metabolism. Early treatment for these conditions may prevent complications in the future.

References

Dietzen DJ, Willrich MAV. Amino acids, peptides, and proteins. In: Rifai N, Chiu RWK, Young I, Burnham Carey-Ann D, Wittwer CT, eds. Tietz Textbook of Laboratory Medicine. 7th ed. St Louis, MO: Elsevier; 2023:chap 31.

Kliegman RM, St. Geme JW, Blum NJ, et al. Defects in metabolism of amino acids. In: Kliegman RM, St. Geme JW, Blum NJ, et al, eds. Nelson Textbook of Pediatrics. 22nd ed. Philadelphia, PA: Elsevier; 2025:chap 105.

Merritt JL, Gallagher RC. Inborn errors of carbohydrate, ammonia, amino acid, and organic acid metabolism. In: Gleason CA, Sawyer T, eds. Avery's Diseases of the Newborn. 11th ed. Philadelphia, PA: Elsevier; 2024:chap 29.

Riley RS, McPherson RA. Basic examination of urine. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Philadelphia, PA: Elsevier; 2022:chap 29.