Alcohol Dehydrogenase Unit Converter
Alcohol Dehydrogenase Unit Converter
This is the enzyme, not the alcohol. If you are looking for a blood alcohol level, you want the blood alcohol converter or the Widmark blood alcohol calculator — this page converts the catalytic activity of alcohol dehydrogenase between U/L, IU/L, µkat/L and nkat/L, which is a liver enzyme measurement ordered for entirely different reasons.
Alcohol dehydrogenase converter
Activity unitsSerum alcohol dehydrogenase 0.30 U/L
Formula and conversion factor
U/L = µkat/L × 60
nkat/L = U/L × 16.667 · IU/L = U/L
- U
- 1 unit = 1 µmol of substrate converted per minute under the assay’s own conditions. Which substrate, at what pH and at what temperature, is a property of the method and not of the unit
- kat
- 1 katal = 1 mol of substrate converted per second — the SI unit of catalytic activity. A katal is an enormous quantity, which is why serum activities are quoted in microkatals and nanokatals
- ÷ 60
- the entire conversion. Per minute against per second, and a micromole against a mole: 1 U/L = 10⁻⁶ mol ÷ 60 s ÷ L = 1.6667 × 10⁻⁸ mol/s/L = 0.0166667 µkat/L = 16.6667 nkat/L. No molecular weight appears anywhere, because an activity is a rate and not a mass
- IU/L
- numerically identical to U/L. The I is a historical label; it adds nothing arithmetically here
- what does not convert
- a blood alcohol concentration. That is a mass of ethanol per volume, in mg/dL, g/L or mmol/L, and no factor relates it to an enzyme activity. They are different quantities measuring different things
Worked example
Serum alcohol dehydrogenase 0.30 U/L
0.30 ÷ 60 = 0.0050 µkat/L
= 5.0 nkat/L = 0.30 IU/L
Inside the 0.07–0.56 U/L range one published series established for its own coenzyme-recycling method — a figure the table below explains you should not treat as a reference interval
Note the scale: a normal ALT runs in the tens of U/L, so an ADH quoted in the tens is almost certainly not an ADH
If the number you are holding is a blood alcohol in mg/dL or mmol/L, this is the wrong page — use the blood alcohol converter
The two things called ADH on a request form, and the third one
| Alcohol dehydrogenase | Blood alcohol level | Antidiuretic hormone | |
|---|---|---|---|
| What is measured | The catalytic activity of a hepatic zinc metalloenzyme | The concentration of ethanol in blood or serum | A posterior pituitary peptide hormone, vasopressin |
| Units | U/L, IU/L, µkat/L, nkat/L | mg/dL, mg/L, g/L, g/dL, mmol/L | pg/mL, pmol/L |
| Why it is ordered | Rarely, and as a marker of hepatocellular damage | Intoxication, fitness to drive, the osmolal gap, toxic alcohol workup | Diabetes insipidus, SIADH, hyponatraemia |
| Order of magnitude | Fractions of a unit per litre | Tens to hundreds of mg/dL | Single-figure pg/mL |
| Converts to the others? | No | No | No |
| Its own page | this page | blood alcohol converter and the Widmark blood alcohol calculator | the vasopressin converter |
The enzyme is also the reagent, which is where much of the confusion starts
| Role | What is happening |
|---|---|
| ADH in the patient | Oxidises ethanol to acetaldehyde in the liver, using NAD⁺ as coenzyme. This is the rate-limiting step of ethanol elimination and the reason blood alcohol falls linearly rather than exponentially |
| ADH in the analyser | The enzymatic ethanol assay used by most clinical laboratories works by adding alcohol dehydrogenase to the specimen and measuring the NADH produced, spectrophotometrically. The enzyme is the detection system |
| ADH as a drug target | Fomepizole inhibits alcohol dehydrogenase, which is the whole basis of its use in methanol and ethylene glycol poisoning: blocking the enzyme stops the parent alcohol being converted into the toxic metabolites |
| ADH as a genetic variable | Polymorphisms in the ADH genes, alongside aldehyde dehydrogenase variants, affect ethanol metabolism and are studied in relation to alcohol use disorder |
What a serum ADH activity has been shown to do
| Finding | What the source reports |
|---|---|
| Normal range | "0.07–0.56 U/l", with 0.50 U/l taken as the upper normal limit, by a coenzyme-recycling method in which a unit is "the rate of consumption of 1 μmol of NDMA per minute" |
| Acute viral hepatitis | Activity "rose steeply, reaching the peak approximately one week after the onset" and "reached up to 70 times its upper normal limit" |
| Cirrhosis | "the lowest mean ADH activities" of the groups studied, consistent with progressive loss of functional liver mass |
| Intrahepatic versus extrahepatic cholestasis | The one genuinely distinctive result: in extrahepatic cholestasis "ADH activity was within the normal range", while in intrahepatic cholestasis it "was elevated, frequently more significantly than other liver enzyme activities" |
| Toxic liver damage | "Class I isoenzymes exceeded the mean control value more than two times, and class II by about 30%", with class II correlating with alanine aminotransferase; the authors conclude they "may be diagnostically useful in toxic hepatitis" |
| The authors’ own verdict | An indicator "reflecting sensitively, though not selectively, the degree of hepatocellular damage, whether due to infection, drug toxicity, inflammation or even malignancy" |
The enzyme, not the alcohol level
First, the disambiguation, because the name on the legacy version of this page invited exactly the wrong search. Alcohol dehydrogenase is a zinc-containing hepatic enzyme that oxidises ethanol to acetaldehyde. A blood alcohol level is the concentration of ethanol in a specimen. They are ordered for entirely different reasons — one is a liver enzyme, the other decides whether somebody is intoxicated — and no arithmetic relates them, because an enzyme activity is a rate and a blood alcohol is a mass per volume. If what you have is a number in mg/dL, mg/L, g/L or mmol/L against a legal or clinical threshold, the pages you want are the blood alcohol converter and the Widmark blood alcohol calculator, and neither of them needs anything from this one.
The conversion on this page is the standard enzyme activity ladder and it has one step in it. A unit is one micromole of substrate converted per minute; a katal is one mole per second. Dividing by sixty converts between the per-minute and per-second conventions, and the micromole-to-mole step supplies the prefix, so one unit per litre is 0.0166667 microkatals per litre and 16.6667 nanokatals per litre. International units per litre are numerically identical to units per litre. No molecular weight enters the calculation at any point, because nothing here is a mass. What the unit does not tell you is the assay’s substrate, pH and temperature, which are properties of the method — and for this particular enzyme that caveat is unusually heavy, because the methods are not standardised.
Which brings us to the honest part. Serum alcohol dehydrogenase has been studied as a liver enzyme since the 1960s and has never entered routine practice. The best-characterised series established a normal range of 0.07 to 0.56 U/L using a coenzyme-recycling method in which the unit was defined by the consumption of a specific artificial substrate — note the scale, which is fractions of a unit per litre where an ALT is in the tens. It found activity rising steeply in acute viral hepatitis, peaking about a week after onset and reaching up to seventy times the upper normal limit; the lowest activities in cirrhosis; and one finding that is genuinely its own, that ADH stays within the normal range in extrahepatic cholestasis while rising, often more than the other liver enzymes, in intrahepatic cholestasis. A later series in toxic liver damage found class I isoenzyme activity more than doubled and class II up by about thirty per cent, with class II tracking ALT. The investigators’ own conclusion is the one to carry away: ADH reflects, sensitively but not selectively, the degree of hepatocellular damage, whatever its cause.
That is a description of what ALT and AST already do, and those are cheap, harmonised and available everywhere. The cholestasis discrimination would be worth something if it were reproducible, but it rests on a single series using a bespoke assay, and no major reference laboratory catalogue offers a serum ADH today. This page therefore ships with no reference interval and no coloured bar: putting a verdict of "within range" or "above range" against a forty-year-old figure from a method almost certainly different from whichever one produced your result would be a confidence the number cannot support. The published figures are in the table above with the method named beside them, which is what they can honestly be used for.
One last thing that is worth knowing precisely because it feeds the confusion. Alcohol dehydrogenase is not only the enzyme being measured here; it is also the reagent in the enzymatic ethanol assay that most clinical laboratories use for blood alcohol, where added ADH oxidises the specimen’s ethanol and the NADH produced is measured spectrophotometrically. It is the target of fomepizole, which treats methanol and ethylene glycol poisoning by blocking the conversion of those alcohols into their toxic metabolites. And its gene variants, with those of aldehyde dehydrogenase, shape how individuals metabolise ethanol. So the enzyme sits behind the measurement, the antidote and the pharmacogenetics of drinking — while a serum ADH activity, the thing this page converts, measures none of those. For the liver, use the ALT converter and the glutamate dehydrogenase converter; for the alcohol, use the blood alcohol converter.
Frequently asked questions
Is alcohol dehydrogenase the same as a blood alcohol level?
No, and nothing converts between them. Alcohol dehydrogenase is a hepatic enzyme and is reported as a catalytic activity in U/L, IU/L, µkat/L or nkat/L. A blood alcohol level is the concentration of ethanol in a specimen and is reported in mg/dL, mg/L, g/L, g/dL or mmol/L. One is a rate, the other a mass per volume; they are different physical quantities measured for different reasons. For an ethanol concentration use the blood alcohol converter.
How do I convert alcohol dehydrogenase from U/L to µkat/L?
Divide by 60. A unit is one micromole of substrate converted per minute and a katal is one mole per second, so 1 U/L = 10⁻⁶ mol ÷ 60 s ÷ L = 0.0166667 µkat/L, which is 16.6667 nkat/L. Going the other way, multiply the µkat/L figure by 60. International units per litre are numerically the same as units per litre, so no conversion is needed between those two.
What is a normal serum alcohol dehydrogenase activity?
No harmonised reference interval exists and none is offered here. The best-characterised series established 0.07 to 0.56 U/L, with 0.50 U/L as the upper normal limit, using a coenzyme-recycling method whose unit was defined by the consumption of a specific artificial substrate. That figure belongs to that method. Serum ADH is not offered by major reference laboratories today, so a result in hand should be read against whatever interval the measuring laboratory printed with it.
What is serum alcohol dehydrogenase used for clinically?
Very little, honestly. It rises steeply in acute viral hepatitis — up to seventy times the upper normal limit, peaking about a week after onset — is lowest in cirrhosis, and rises in toxic liver damage. The one distinctive finding is that it stays normal in extrahepatic cholestasis while rising in intrahepatic cholestasis, often more than the other liver enzymes. The investigators described it as reflecting hepatocellular damage "sensitively, though not selectively", which is what ALT and AST already do more cheaply and more reproducibly.
Why does the enzymatic blood alcohol test use alcohol dehydrogenase?
Because it is a convenient and specific way to detect ethanol. The assay adds alcohol dehydrogenase to the specimen; the enzyme oxidises any ethanol present to acetaldehyde, reducing NAD⁺ to NADH, and the NADH is measured spectrophotometrically. The enzyme is the detection chemistry, not the analyte. That is a common source of confusion — searching for "alcohol dehydrogenase" after a blood alcohol result returns the enzyme, which is not what was reported.
Why is there no reference interval bar on this page?
Because one series from 1982, using a method almost certainly unlike whichever produced your result, is not enough to give anybody a verdict on. Enzyme activity units are method-dependent by definition — the substrate, pH and temperature belong to the assay and not to the unit — and serum ADH has never been harmonised or widely offered. The published figures are in the table above with their method stated, which is the only way they can honestly be used. The converter still converts.
Related calculators
References
- Khayrollah AA, Al-Tamer YY, Taka M, Skursky L. Serum alcohol dehydrogenase activity in liver diseases. Ann Clin Biochem. 1982;19(1):108–115. Normal range "0.07–0.56 U/l", upper normal limit "0.50 U/l"; unit defined as "the rate of consumption of 1 μmol of NDMA per minute"; in viral hepatitis activity "reached up to 70 times its upper normal limit"; in extrahepatic cholestasis "ADH activity was within the normal range" while in intrahepatic cholestasis it "was elevated, frequently more significantly than other liver enzyme activities"; conclusion — an indicator "reflecting sensitively, though not selectively, the degree of hepatocellular damage".
- Serum activities of classes I and II alcohol dehydrogenases in toxic liver damage. Clin Chim Acta. 1997. "Class I isoenzymes exceeded the mean control value more than two times, and class II by about 30%"; class II correlated with alanine aminotransferase; "alcohol dehydrogenase and class I isoenzymes are indicatory enzymes of liver cell damage, and may be diagnostically useful in toxic hepatitis".
- Improved assay for alcohol dehydrogenase activity in serum by centrifugal analysis. Clin Chem. 1984, and differential pulse polarographic assay reporting measurement "in rat liver tissue and human serum with a high degree of sensitivity and accuracy (ranging from 1 to 200 U/l)".
- data/_factors.json, analyte
alcohol_dehydrogenase: activity, source "Katal definition"; "Note this is the ENZYME, not a blood alcohol measurement — the two are ordered for completely different reasons." - Bureau International des Poids et Mesures. The International System of Units. The katal, mol/s, as the SI derived unit of catalytic activity; 1 U = 1 µmol/min, so 1 U/L = 16.6667 nkat/L.
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.