Optimal Result: 1 - 86.7 umol/g Cr.

Aspartic acid is a nonessential amino acid that plays roles in many important metabolic processes, such as energy production (citric acid cycle), hormone metabolism, CNS activation, and the urea cycle. It is found in many protein sources such as oysters, meats, seeds, avocado, asparagus, and beets. It is also an ingredient in artificial sweeteners.

Aspartic acid is a precursor to many amino acids and other molecules like asparagine, arginine, isoleucine, lysine, methionine, isoleucine, threonine, nucleotides, NAD, and pantothenate. Aspartate, like glutamine, can also be considered a neuroexcitatory neurotransmitter since it activates the N-methyl-D-aspartate receptor in the brain.

Aspartate transaminase (AST) is an enzyme that catalyzes the transfer of an amino group from L-aspartate to alpha-keto glutarate. This reaction serves as a cellular energy source and takes place mainly in the liver, skeletal muscle, myocardium, and kidneys. Although AST is commonly measured on traditional laboratory profiles as a measure of liver dysfunction and muscle injury, it is not specific enough to be used alone as a diagnostic tool.


- NCIthesaurus. Aspartic Acid. 2020.

- Reitzer L. Biosynthesis of Glutamate, Aspartate, Asparagine, L-Alanine, and D-Alanine. EcoSal Plus. 2004;1(1).

- Kobylarek D, Iwanowski P, Lewandowska Z, et al. Advances in the potential biomarkers of epilepsy. Front Neurol. 2019;10.

- Ono K, Ono T, Matsumata T. The pathogenesis of decreased aspartate aminotransferase and alanine aminotransferase activity in the plasma of hemodialysis patients: the role of vitamin B6 deficiency. Clinical Nephrol. 1995;43(6):405-408.

- Lomelino CL, Andring JT, McKenna R, Kilberg MS. Asparagine synthetase: Function, structure, and role in disease. J Biol Chem. 2017;292(49):19952-19958.

- Stegink LD, Filer LJ, Jr., Bell EF, Ziegler EE. Plasma amino acid concentrations in normal adults administered aspartame
in capsules or solution: lack of bioequivalence. Metabolism: Clin Exp. 1987;36(5):507-512.

What does it mean if your Aspartate result is too low?

- Low urinary aspartate can result from general dietary protein insufficiency, maldigestion, or possibly B-6 deficiency.

- Low levels have been linked to feelings of fatigue and low mood, whereas high levels have been linked to seizures and anxiousness.

- Inhibits ammonia detoxification in the urea cycle. Can be converted to oxaloactetate using B6 and α-KG and thus enter the Krebs cycle.

- Citric and aspartic acids can drive the Krebs (citric acid) cycle, when combined with B6 and α-KG.

What does it mean if your Aspartate result is too high?

Elevated aspartic acid may reflect high intake of aspartate- rich foods or use of artificial sweeteners containing aspartic acid (“NutraSweet” or “Equal”).

Elevations may also be due to impaired downstream metabolism from nutritional insufficiencies of enzymatic cofactors such as vitamin B6, magnesium, and ATP.

Because aspartic acid is a major excitatory neurotransmitter, elevations have been noted in epileptic patients.

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