Valine Unit Converter
Valine Unit Converter
Convert valine between mg/dL and µmol/L — with its own factor, not leucine's — and see why valine rises with leucine in maple syrup urine disease but is not the amino acid watched for decompensation, and is more often supplemented than restricted.
Valine converter
mg/dL ⇄ µmol/LValine 2.6 mg/dL on a fasting profile, read against the adult reference interval
Formula and conversion factor
mg/dL = µmol/L ÷ 85.3606
- 85.3606
- derived from the molecular weight of L-valine, 117.15 Da. Valine is one methylene group smaller than leucine, so it has its own factor and not leucine's
- not 76.2369
- that is the leucine and isoleucine factor, from their shared molecular weight of 131.17 Da. Using it on a valine overstates the result by about 12%, which is the commonest arithmetic error on a branched-chain profile
- the 2:1 rule
- MSUD guidance keeps plasma valine at least twice the plasma leucine, with a leucine:valine molar ratio of 0.5 or less. The valine target therefore moves with the leucine instead of being a fixed range
- leucine is monitored
- not valine. Changes in plasma leucine during a crisis mirror whole-body protein turnover, and leucine is the branched-chain amino acid that drives the encephalopathy
Worked example
Valine 2.6 mg/dL on a fasting profile, read against the adult reference interval
2.6 × 85.3606 = 221.94 µmol/L, reported as 222 µmol/L
Within the Mayo adult interval of 134–357 µmol/L used here, and within Labcorp's 102.6–345.4 µmol/L
Using the leucine factor by mistake would give 2.6 × 76.2369 = 198 µmol/L — about 12% adrift, and in the direction that makes a valine look lower than it is
Read against the derived MSUD figures of 300–600 µmol/L, the same 222 µmol/L is below range. In a treated child that prompts valine supplementation, not reassurance
And against a leucine of 200 µmol/L, the aim is a valine of at least 400 — so the figure to compare with is not fixed, it moves with the leucine measured on the same sample
The three branched-chain amino acids do not share one factor
| Amino acid | Molecular weight (Da) | mg/dL → µmol/L factor | Role in MSUD |
|---|---|---|---|
| Leucine | 131.17 | 76.2369 | The neurotoxic one, and the analyte monitored. Maintenance target 150–300 µmol/L |
| Isoleucine | 131.17 | 76.2369 — an isomer of leucine, same mass | Kept roughly equal to the leucine; supplemented if it falls, which otherwise causes a skin rash |
| Valine | 117.15 | 85.3606 — a smaller molecule, its own factor | Kept at least twice the leucine. Continuous fortification is linked to long-term intellectual outcome |
| Alloisoleucine | 131.17 | 76.2369 | Normally under 5 µmol/L; above that in 94–99.9% of MSUD. The diagnostic marker |
Where the MSUD valine figures on this page come from
| Published figure | Source | What it gives for valine |
|---|---|---|
| Plasma leucine maintenance target 150–300 µmol/L | MSUD nutrition guidance | The anchor. Leucine is what is monitored |
| Plasma valine at least twofold plasma leucine | MSUD nutrition guidance | Valine of at least 300–600 µmol/L when leucine is at target |
| Leucine : valine molar ratio 0.5 or less | MSUD nutrition guidance | The same rule stated the other way round |
| 300–600 µmol/L | Derived on this page, not published as an interval | The group offered above, and it moves if the leucine moves |
The branched-chain amino acid that is supplemented, not restricted
Valine is one of the three branched-chain amino acids, with leucine and isoleucine, and like them it is essential and broken down through the branched-chain alpha-ketoacid dehydrogenase complex. It is the smallest of the three, with a molecular weight of 117.15 Da, and that has an arithmetic consequence worth stating first: valine converts at 85.36 µmol/L per mg/dL, while leucine and isoleucine — isomers of one another at 131.17 Da — convert at 76.24. Applying the leucine factor to a valine understates it by about 12 per cent, and ‘the branched-chain amino acids’ is exactly the phrase that invites the mistake.
All three accumulate when that dehydrogenase complex is deficient, in maple syrup urine disease. But they are not managed alike. Leucine is the neurotoxic one: leucine and its ketoacid drive the encephalopathy and cerebral oedema of a crisis, changes in plasma leucine during a crisis mirror whole-body protein turnover, and leucine is therefore the amino acid monitored, with a maintenance target of roughly 150 to 300 µmol/L. Valine and isoleucine are far less neurotoxic, and on treatment the usual problem is that they fall too low rather than rise too high.
So valine is supplemented more often than it is restricted. The guidance keeps plasma valine at least twice the plasma leucine, with a leucine to valine molar ratio of 0.5 or less, and continuous valine fortification has been linked to long-term intellectual outcome. That makes the valine target relational rather than fixed: it moves with the leucine measured on the same sample. The 300 to 600 µmol/L offered as a group on this page is that rule applied to the published leucine target, and it is labelled as derived because that is what it is.
Two cautions close the picture. A rising leucine during intercurrent illness in someone known to have maple syrup urine disease is a metabolic emergency, managed through the family’s emergency regimen with the metabolic service contacted the same day — and a valine result neither confirms nor softens that. And the diagnosis itself does not rest on any of these three: alloisoleucine, normally under 5 µmol/L and raised in 94 to 99.9 per cent of people with MSUD, is the sensitive and specific marker. Take a fasting, promptly separated sample, convert it with valine’s own factor, and read it beside the leucine rather than instead of it.
Frequently asked questions
How do I convert valine from mg/dL to µmol/L?
Multiply by 85.3606, derived from the molecular weight of valine, 117.15 Da. A valine of 2.6 mg/dL is 222 µmol/L. To go the other way, divide the µmol/L figure by 85.3606.
Can I use the leucine factor for valine?
No. Leucine and isoleucine are isomers sharing a molecular weight of 131.17 Da and a factor of 76.2369, but valine is a smaller molecule at 117.15 Da and converts at 85.3606. Using the leucine factor on a valine understates it by about 12 per cent.
What is a normal valine level?
Mayo publishes 134–357 µmol/L for fasting adults and Labcorp 102.6–345.4 µmol/L for anyone over 15, with different bands for children and infants. Use the interval your own laboratory prints for that age, on a fasting sample separated promptly.
Is valine monitored in maple syrup urine disease?
It is measured, but leucine is what is monitored for control and for decompensation, because leucine is the neurotoxic branched-chain amino acid and its changes during a crisis mirror whole-body protein turnover. Valine is checked mainly to make sure it has not fallen too low.
Why is valine supplemented in MSUD?
Because it is essential, and on a branched-chain-restricted diet it tends to fall too low. The guidance keeps plasma valine at least twice the plasma leucine, with a leucine to valine ratio of 0.5 or less, and continuous valine fortification has been linked to long-term intellectual outcome. The target moves with the leucine rather than being a fixed range, and it is set by the metabolic service.
Related calculators
References
- Strauss KA, Carson VJ, Puffenberger EG. Maple Syrup Urine Disease. In: GeneReviews. Seattle: University of Washington; 2006, updated 2020.
- Frazier DM, Allgeier C, Homer C, et al. Nutrition management guideline for maple syrup urine disease: an evidence- and consensus-based approach. Mol Genet Metab. 2014;112(3):210–217.
- 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.