Urine Copper Unit Converter
Urine Copper Unit Converter
A 24-hour urinary copper is the Wilson disease test, and it is an amount per collection rather than a concentration. Convert µg/24 h and nmol/24 h.
Urine Copper converter
Mass ⇄ molar, per 24 hA 24-hour urinary copper reported as 1,600 nmol/24 h, collection complete
The conversion, and why there is no volume in it
µg/24 h = nmol/24 h ÷ 15.7366
µmol/24 h = nmol/24 h ÷ 1,000
- 63.546
- the atomic weight of copper — the same figure the serum copper page uses, because it is the same element
- per 24 hours, not per litre
- the collection volume is already inside the number, so a concentration in the bottle says only how much the patient drank
- 0.6 and 1.6 µmol
- how the 40 and 100 µg/24 h Wilson thresholds are quoted in SI units; derived from the atomic weight they are 0.630 and 1.574 µmol, which round to the published figures
Worked example
A 24-hour urinary copper reported as 1,600 nmol/24 h, collection complete
1,600 ÷ 15.7366 = 101.7 µg/24 h
= 1.6 µmol/24 h
Above Mayo's reference interval of 9 to 71 µg/24 h, and above the 100 µg/24 h quoted for symptomatic Wilson disease
Not diagnostic on its own: check caeruloplasmin, serum copper, the liver and the eyes, and exclude cholestasis and nephrotic syndrome
Converting a 24-hour urinary copper
| µg/24 h | nmol/24 h | µmol/24 h |
|---|---|---|
| 9 | 142 | 0.142 |
| 40 | 629 | 0.629 |
| 60 | 944 | 0.944 |
| 71 | 1,117 | 1.117 |
| 100 | 1,574 | 1.574 |
Reference intervals and the Wilson disease cut-offs
| Source and basis | Figure | Unit |
|---|---|---|
| Mayo CUU, adults 18 and over | 9 – 71 | µg/24 h |
| ARUP, all ages | 3.0 – 45.0 | µg/day |
| Mayo CUU text, humans normally excrete less | Below 60 | µg/day |
| GeneReviews, raised in most with Wilson disease | Above 40 | µg/24 h |
| GeneReviews, symptomatic Wilson disease | Above 100 | µg/24 h |
An amount, not a concentration
This is the Wilson disease test, and the first thing to understand about it is the denominator. A 24-hour urinary copper is an amount per collection, not a concentration: the volume has already been multiplied in, which is why this page offers no µg/L or µg/dL. The practical consequence is that an under-collected bottle produces a low result in a patient whose copper excretion is entirely normal — and, worse, a normal-looking result in a patient whose excretion is high. Check the urine creatinine on the same collection before believing either direction.
The arithmetic is straightforward once the family is fixed. Copper’s atomic weight is 63.546, so 1 µg/24 h is 15.7366 nmol/24 h and 100 µg/24 h is 1.574 µmol/24 h. That derivation is a useful check on the literature: GeneReviews quotes the Wilson thresholds as above 40 µg or roughly 0.6 µmol/24 h, and above 100 µg or roughly 1.6 µmol/24 h in symptomatic disease, and the molecular weight gives 0.629 and 1.574 µmol — the same numbers rounded.
The reference intervals disagree enough to change an answer. Mayo gives 9 to 71 µg/24 h for adults and separately observes that humans normally excrete less than 60 µg a day; ARUP gives 3.0 to 45.0 µg/day for all ages. The 40 µg/24 h figure that marks out most patients with Wilson disease is inside Mayo’s interval and close to the top of ARUP’s, so the same result can be reported as normal or as abnormal depending on which laboratory ran it. This is the strongest argument on the page for reading the interval printed on your own report rather than any figure quoted here.
A raised 24-hour urinary copper is not specific to Wilson disease. Obstructive biliary disease and other cholestasis raise it, as do nephrotic syndrome and oestrogen therapy, and copper is handled quite differently in serum, where most of it is carried on caeruloplasmin — which is why a caeruloplasmin and a serum copper are interpreted together rather than separately. Wilson disease is diagnosed on a composite of findings, not on this number alone.
Frequently asked questions
How do I convert a 24-hour urinary copper from µg to nmol?
Multiply by 15.7366, derived from copper’s atomic weight of 63.546. For µmol/24 h, divide the nmol figure by a thousand: 100 µg/24 h is 1.574 µmol/24 h.
Why does this page offer no µg/L or µg/dL?
Because a 24-hour excretion and a concentration are different quantities, and relating them needs the collection volume. The volume is already inside a per-24-hour figure; a concentration in the bottle reflects fluid intake rather than copper handling.
What 24-hour urinary copper suggests Wilson disease?
Basal excretion, measured without a chelating agent, is above 40 µg (about 0.6 µmol) per 24 hours in most affected people and above 100 µg (about 1.6 µmol) in symptomatic disease. The diagnosis is composite and this result is one component of it.
Why do Mayo and ARUP give different reference intervals?
Different methods and reference populations: Mayo gives 9 to 71 µg/24 h by ICP-MS/MS for adults, ARUP 3.0 to 45.0 µg/day. The overlap with the 40 µg Wilson threshold is the reason to use the interval printed on your own report.
What else raises a 24-hour urinary copper?
Obstructive biliary disease and other cholestasis, nephrotic syndrome, and oestrogen therapy. An incomplete collection does the opposite, lowering the result without anything having changed in the patient.
Related calculators
References
- Mayo Clinic Laboratories. Copper, 24 hour, urine (CUU) — reference values and interpretation. Test catalogue, test ID 8590; 2026.
- ARUP Laboratories. Copper, urine — reference interval per 24 hours. Laboratory Test Directory 0020461, component test 0020101; 2026.
- Wilson disease. In: GeneReviews. Seattle: University of Washington; NCBI Bookshelf NBK1512, updated 2023.
- Commission on Isotopic Abundances and Atomic Weights, IUPAC. Standard Atomic Weights 2024. Accessed October 2026.
Not medical advice. For healthcare professionals and education. Reference intervals vary by laboratory and assay — always use your own laboratory's. Never base a dose or a treatment decision on this page alone. Full disclaimer at calcengines.com/disclaimer/