Glutamic Acid Unit Converter
Glutamic Acid Unit Converter
Convert glutamic acid — glutamate — between mg/dL and µmol/L, with fasting reference intervals by age, and see why a raised plasma glutamate is far more often a haemolysed or slowly separated sample than a finding.
Glutamic Acid converter
mg/dL ⇄ µmol/LGlutamic acid 1.00 mg/dL on a fasting plasma amino acid profile, separated promptly, read against the adult interval
Formula and conversion factor
mg/dL = µmol/L ÷ 67.9671
- 67.9671
- derived from the molecular weight of L-glutamic acid, 147.13 Da (C5H9NO4, PubChem CID 33032)
- glutamine is the partner
- 146.14 Da, a factor of 68.4291. Glutamine is glutamate with an amide group carrying an extra nitrogen, so the two differ by under one per cent in mass and completely in meaning: glutamine transports ammonia and rises in urea cycle disorders, glutamate is its deaminated form
- the tube, not the patient
- red cells contain far more glutamate than plasma, so haemolysis and delayed separation release it. Concentrations rise more than fivefold over 24 hours at room temperature and the rise is largely prevented on ice
- so handle it properly
- blood for plasma amino acids goes immediately on ice, or the plasma is separated and frozen within 30 minutes. A glutamate is only readable against a reference interval if that happened
Worked example
Glutamic acid 1.00 mg/dL on a fasting plasma amino acid profile, separated promptly, read against the adult interval
1.00 × 67.9671 = 67.97 µmol/L, reported as 68 µmol/L
Within the Mayo adult interval of 13–148 µmol/L used here, and within Labcorp's 18.1–155.9 µmol/L
The same 1.00 mg/dL as a glutamine would be 68 µmol/L too — the factors differ by under one per cent — but a glutamine of 68 µmol/L would be well below its own adult interval of 447–774 µmol/L. Identical arithmetic, opposite verdict
And had this sample sat at room temperature for a day, the measured figure could have been fivefold higher with nothing wrong with the patient. The handling is part of the result
Two published intervals, in unusual agreement
| Source | Adult (µmol/L) | Children (µmol/L) | Younger bands (µmol/L) |
|---|---|---|---|
| Mayo Clinic Laboratories — LC-MS/MS, fasting | 13 – 148 (≥18 y) | 16 – 182 (2–17 y) | 28 – 376 (<24 months) |
| Labcorp — plasma amino acid intervals | 18.1 – 155.9 (>15 y) | 18.4 – 142.2 (2–15 y) | 27.0 – 195.5 (31 d–23 m); 38.0 – 398.9 (0–30 d) |
Glutamate and glutamine: one per cent apart in mass, and not interchangeable
| Analyte | MW (Da) | mg/dL → µmol/L | Adult interval (Mayo, µmol/L) | What it tells you |
|---|---|---|---|---|
| Glutamine (Gln) | 146.14 | 68.4291 | 447 – 774 | The body’s ammonia transporter and the largest free amino acid pool in plasma. A raised glutamine with a raised ammonia is part of the urea cycle pattern, and it can rise before the ammonia does |
| Glutamic acid (Glu) | 147.13 | 67.9671 | 13 – 148 | Glutamine’s deaminated partner, and thirty times less abundant in plasma. Highly sensitive to haemolysis and to delayed separation, so a raised value is usually pre-analytical |
Glutamate is the amino acid the tube changes most
Glutamic acid, usually called glutamate, is the central carbon skeleton of amino acid nitrogen handling: transaminases move amino groups on and off it, glutamate dehydrogenase releases that nitrogen as ammonia, and glutamine synthetase attaches it again as an amide. Its molecular weight is 147.13 Da, so 1 mg/dL is 67.97 µmol/L. Glutamine, its amidated partner, is 146.14 Da and converts at 68.4291 — the two factors differ by under one per cent.
That near-identity is worth knowing because the two analytes are read in opposite ways. Glutamine is the largest free amino acid pool in plasma, published by Mayo at 447–774 µmol/L in fasting adults, and it is the vehicle that carries ammonia between tissues, so a raised glutamine belongs to the urea cycle pattern and can rise before the ammonia itself does. Glutamate is its deaminated form, some thirty times less abundant, published at 13–148 µmol/L. Convert the wrong one and the arithmetic looks fine while the verdict inverts.
The more important caution is pre-analytical. Red cells hold far more glutamate than plasma does, so anything that releases their contents — visible haemolysis, a difficult capillary sample, or simply leaving the blood to stand before the plasma is taken off — raises the measured concentration. When this was quantified directly, glutamate was the extreme case among the amino acids: it rose more than fivefold over 24 hours at room temperature, where most others moved by more than ten per cent, and the rise was largely or completely prevented in blood placed straight on ice. The published advice is explicit — blood for plasma amino acids goes immediately on ice, or the plasma is separated and frozen within thirty minutes.
So a raised plasma glutamate is far more often a statement about the sample than about the person, and the reference intervals themselves say as much: more than tenfold wide in adults and wider still in infants. Read a glutamate beside the glutamine, the alanine and the ammonia from the same fasting, promptly separated sample, and if it is high in isolation, the first step is to repeat it properly rather than to explain it. Where the pattern does matter — hyperammonaemia, a suspected urea cycle disorder, a child being monitored on a protein-restricted diet — the interpretation belongs to a metabolic service, which reads the profile as a whole and never a single converted number.
Frequently asked questions
How do I convert glutamic acid from mg/dL to µmol/L?
Multiply by 67.9671, derived from the molecular weight of glutamic acid, 147.13 Da. A glutamate of 1.00 mg/dL is 68 µmol/L. To go the other way, divide the µmol/L figure by 67.9671.
Is glutamic acid the same as glutamate?
Yes — glutamate is the ionised form that exists at physiological pH, and reports use the names interchangeably, usually abbreviated Glu. Glutamine, abbreviated Gln, is a different analyte: glutamate with an amide group, 146.14 Da, and an adult interval some thirty times higher.
Why is my glutamate high?
The first thing to check is the sample. Red cells contain far more glutamate than plasma, so haemolysis or a delay before the plasma is separated releases it, and measured concentrations rise more than fivefold over 24 hours at room temperature. A raised glutamate on a sample that was not chilled and separated promptly is usually an artefact, and the right next step is a properly handled repeat.
What is a normal glutamic acid level?
Mayo publishes 13–148 µmol/L for fasting adults and Labcorp 18.1–155.9 µmol/L for over-15s, with wider intervals in children and infants. The two agree closely here, unlike some other amino acids, but both intervals are more than tenfold wide. Use the one your own laboratory prints for that age.
How should blood for plasma amino acids be handled?
Fasting, and on ice immediately — or with the plasma separated and frozen within thirty minutes. Mayo requires four hours of fasting and asks that infants be sampled before the next feed. Most amino acids drift by more than ten per cent over a day at room temperature, and glutamate by more than fivefold.
Related calculators
References
- Davis JS, Darcy CJ, Piera K, et al. Ex-vivo changes in amino acid concentrations from blood stored at room temperature or on ice: implications for arginine and taurine measurements. BMC Clin Pathol. 2009;9:10.
- Mayo Clinic Laboratories. Test ID: AAQP — Amino Acids, Quantitative, Plasma. Liquid chromatography tandem mass spectrometry. Reference values are for fasting patients, in three age bands (under 24 months, 2–17 years, 18 years and over). Accessed 2026.
- Labcorp. Plasma Amino Acid Reference Intervals — four age bands from 0–30 days to over 15 years, µmol/L. Accessed 2026.
Medical Disclaimer: The tools and content provided here are for educational and reference purposes only. They are not intended to substitute for professional medical advice, diagnosis, or treatment. Clinical decisions should always be based on the comprehensive assessment of a qualified healthcare professional.