Glutamine Unit Converter
Glutamine Unit Converter
Convert glutamine between mg/dL and µmol/L, with the 1,000 µmol/L ceiling from the urea cycle guidelines — because glutamine is where waste nitrogen is stored, and it can still be raised after the ammonia has come back down.
Glutamine converter
mg/dL ⇄ µmol/LGlutamine 8.0 mg/dL on a fasting profile, read against the adult reference interval
Formula and conversion factor
mg/dL = µmol/L ÷ 68.4275
- 68.4275
- derived from the molecular weight of L-glutamine, 146.14 Da. Glutamine is glutamate with the side-chain carboxyl replaced by an amide — the extra nitrogen that lets it carry ammonia
- 1,000 µmol/L
- the ceiling the 2019 urea cycle disorder guidelines describe: glutamine levels not exceeding 1,000 µmol/L are considered tolerable, and a rising glutamine may indicate impending hyperammonaemia
- two amide nitrogens
- glutamine carries surplus nitrogen from tissues to the liver and kidney. That storage role is why it moves with ammonia, and why it moves more slowly
- unstable in the tube
- glutamine deamidates to glutamate in unseparated blood, and glutamate has been measured rising more than fivefold over 24 hours at room temperature. A delayed sample understates glutamine
Worked example
Glutamine 8.0 mg/dL on a fasting profile, read against the adult reference interval
8.0 × 68.4275 = 547.42 µmol/L, reported as 547 µmol/L
Within the Mayo adult interval of 447–774 µmol/L used here, and within Labcorp's 332–754 µmol/L
Read against the urea cycle monitoring group instead — a ceiling of 1,000 µmol/L — the same number sits comfortably below it
Which is the ordinary case: people with a urea cycle disorder frequently run in the upper part of the normal range, and the guidelines treat anything up to 1,000 µmol/L as tolerable
A glutamine of 15 mg/dL would be 1,026 µmol/L, above that ceiling, and would prompt a look at the ammonia, the protein intake and the clinical state — not an action taken on the amino acid alone
Glutamine and ammonia move together, but not at the same speed
| Situation | Ammonia | Glutamine | What it means |
|---|---|---|---|
| Stable urea cycle disorder | Normal | Often upper normal | Expected. The guidelines describe up to 1,000 µmol/L as tolerable |
| Before a hyperammonaemic episode | Still normal or rising | Rising | A rising glutamine may indicate impending hyperammonaemia — a reason to look, not a prediction |
| During an episode | High | High | The ammonia is what is acted on, urgently, through the emergency regimen |
| After an episode | Normalised | Still raised | Glutamine is the slower marker and can show that nitrogen was recently in excess when the ammonia no longer does |
| Critical illness, sepsis, burns | Variable | Low | Associated with worse outcomes, but supplementation trials found harm rather than benefit |
Published intervals, and the figure that is not one
| Source | Adult (µmol/L) | Children (µmol/L) | Youngest band (µmol/L) |
|---|---|---|---|
| Mayo Clinic Laboratories — fasting | 447 – 774 (≥18 y) | 353 – 790 (2–17 y) | 356 – 857 (<24 months) |
| Labcorp | 332 – 754 (>15 y) | 330 – 726 (2–15 y) | 264 – 835 (0–30 days) |
| Urea cycle guidelines 2019 — tolerable ceiling, not a reference limit | ≤ 1,000 | ≤ 1,000 | ≤ 1,000 |
Where surplus nitrogen waits
Glutamine is the most abundant amino acid in plasma and the body’s principal carrier of waste nitrogen. It is glutamate with an extra amide nitrogen on the side chain, and that second nitrogen is the point: tissues that generate ammonia attach it to glutamate to make glutamine, which travels safely in the blood to the liver and kidney where the nitrogen is released and disposed of. Converting the number is simple — 1 mg/dL is 68.43 µmol/L, from a molecular weight of 146.14 Da — and glutamine is usually the largest single value on a plasma amino acid profile.
Because it is where surplus nitrogen is stored, glutamine is an indirect marker of ammonia, and it is a slower one. The 2019 urea cycle disorder guidelines state that a rising plasma glutamine may indicate impending hyperammonaemia and that levels not exceeding 1,000 µmol/L are considered tolerable. The other direction is the one clinicians use most: a glutamine that is still raised after the ammonia has come back down can show that nitrogen was recently in excess when the ammonia no longer does. That retrospective reading is standard practice rather than a graded guideline recommendation, and glutamine has not been shown to predict crises reliably, so it belongs alongside the ammonia, the clinical state and the protein intake rather than in front of them.
A low glutamine means something quite different. It is described in critical illness, sepsis, major surgery and burns, where the demand for glutamine exceeds what the body can make, and low levels have been associated with worse outcomes. That association did not survive the obvious experiment: the REDOXS trial found higher mortality among critically ill patients given glutamine supplements. A low glutamine is therefore read as a marker of how ill someone is, not as a deficiency to be topped up.
Two practical points decide whether any of this is readable. Glutamine concentrations change with feeding and are highest after an overnight fast, which is when the published reference samples were taken, so a fed sample cannot be compared with them; in an infant the sample goes immediately before a feed or at the interval the metabolic service specifies. And glutamine deamidates to glutamate in unseparated blood — glutamate has been measured rising more than fivefold over 24 hours at room temperature — so a sample that sat before the plasma was separated understates the glutamine. Fasting, on ice or separated promptly, and read with the ammonia.
Frequently asked questions
How do I convert glutamine from mg/dL to µmol/L?
Multiply by 68.4275, derived from the molecular weight of glutamine, 146.14 Da. A glutamine of 8.0 mg/dL is 547 µmol/L. To go the other way, divide the µmol/L figure by 68.4275.
What is a normal glutamine level?
Mayo publishes 447–774 µmol/L for fasting adults and Labcorp 332–754 µmol/L for anyone over 15, with different bands for children and infants. Glutamine is highest after an overnight fast, so a fed sample is not comparable. Use the interval your own laboratory prints.
Why is glutamine measured in urea cycle disorders?
Because it is where surplus nitrogen is stored, so it tracks ammonia indirectly and more slowly. The 2019 guidelines state that a rising glutamine may indicate impending hyperammonaemia and that levels up to 1,000 µmol/L are tolerable. It can also remain raised after an ammonia has normalised, showing an episode the ammonia no longer does.
Does a raised glutamine mean the ammonia is high?
Not necessarily, and that is part of its usefulness. Glutamine can be raised while the ammonia has already returned to normal, because it is the slower marker. It is read together with the ammonia, the clinical picture and the protein intake, and it has not been shown to predict hyperammonaemic crises reliably on its own.
What does a low glutamine mean?
It is described in critical illness, sepsis, burns and major surgery, and low levels have been associated with worse outcomes. Supplementation is not the answer that follows: the REDOXS trial found higher mortality in critically ill patients given glutamine. A low value is read as a marker of severity rather than a deficiency to correct.
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References
- Häberle J, Burlina A, Chakrapani A, et al. Suggested guidelines for the diagnosis and management of urea cycle disorders: first revision. J Inherit Metab Dis. 2019;42(6):1192–1230.
- Heyland D, Muscedere J, Wischmeyer PE, et al. A randomized trial of glutamine and antioxidants in critically ill patients (REDOXS). N Engl J Med. 2013;368(16):1489–1497.
- Davis JS, Darcy CJ, Piera K, et al. Ex-vivo changes in amino acid concentrations from blood stored at room temperature or on ice. BMC Clin Pathol. 2009;9:10.
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.