Urine Uric Acid Unit Converter
Urine Uric Acid Unit Converter
A 24-hour urine urate is a stone and tumour-lysis test. Convert mg/dL, mg/L, mmol/L and µmol/L, with the mg/24 h multiplier the EAU limits are written in.
Urine Uric Acid converter
Mass ⇄ molarUrine uric acid 40 mg/dL on a spot sample
Formula and conversion factors
µmol/L = mg/dL × 59.4849
mmol/24 h = mg/24 h × 0.00594849
- 168.11
- the molecular weight of uric acid, C5H4N4O3 — PubChem CID 1175, and 168.11 as the formula weight in the RCSB ligand record
- 0.00594849
- excretion factor, mg/24 h to mmol/24 h — the one the EAU stone limits are expressed in
- urate or uric acid
- the same measurement under two names, as in serum
Worked example
Urine uric acid 40 mg/dL on a spot sample
40 × 0.0594849 = 2.379 mmol/L
40 × 59.4849 = 2,379 µmol/L
Over a 1.5 L collection, 600 mg/24 h = 3.57 mmol/24 h
Inside Mayo's 250 to 750 mg/24 h for women and below the EAU's 4 mmol/day limit — but the urine pH matters more than this number for stone risk
Urate: the two multipliers
| Conversion | Multiplier | Worked |
|---|---|---|
| mg/dL to mmol/L (a concentration) | 0.0594849 | 40 mg/dL = 2.379 mmol/L |
| mg/dL to µmol/L | 59.4849 | 40 mg/dL = 2,379 µmol/L |
| mg/24 h to mmol/24 h (an excretion) | 0.00594849 | 600 mg/24 h = 3.57 mmol/24 h |
24-hour urine urate: intervals and stone limits
| Source and basis | Figure | Unit |
|---|---|---|
| Mayo URCU, males 18 and over | 200 – 1,000 | mg/24 h |
| Mayo URCU, females 18 and over | 250 – 750 | mg/24 h |
| ARUP, 24-hour, no sex split | 250 – 750 | mg/day |
| EAU 2026, men, stone risk factor | Above 5.0 | mmol/day |
| EAU 2026, women, stone risk factor | Above 4.0 | mmol/day |
| EAU limits converted to milligrams | Men above 841, women above 672 | mg/day |
| Tumour lysis, random urate/creatinine ratio | Above 1.0 | mg/mg |
Two tests sharing one analyte
A urine urate is asked for two quite different reasons, and the unit you need depends on which. In a stone workup it is part of a 24-hour collection, read against the European Association of Urology’s limits of above 5 mmol/day in men and above 4 mmol/day in women — which are 841 and 672 mg/day. In suspected tumour lysis it is a random sample, read as a urate-to-creatinine ratio against a cut-off of 1.0 mg/mg; see the urine uric acid-creatinine ratio calculator.
The conversions all come from the molecular weight of uric acid, 168.11 g/mol for C5H4N4O3. A concentration goes from mg/dL to mmol/L by multiplying by 0.0594849 or to µmol/L by 59.4849; a daily excretion goes from mg/24 h to mmol/24 h by multiplying by 0.00594849. The last of those is the one the EAU limits are written in, and it is a tenth of the concentration factor. Urate and uric acid are the same measurement under two names, exactly as on the serum urate converter.
The sources disagree in an instructive way. Mayo gives 200 to 1,000 mg/24 h for men and 250 to 750 mg/24 h for women; ARUP gives a single 250 to 750 mg/day with no sex split, which is Mayo’s female interval. Neither laboratory publishes an interval for a random sample, and ARUP says so explicitly. So a man excreting 900 mg/24 h is inside Mayo’s interval and above ARUP’s — and still below the EAU’s stone limit of 5 mmol/day, which is 841 mg. Three sources, three verdicts on one number.
The clinical caution is bigger than any of those thresholds. Uric acid stones form chiefly because the urine is persistently acid, not because the urate load is high: undissociated uric acid is poorly soluble and urate salts are not, so urine pH governs precipitation. A normal 24-hour urate therefore does not exclude uric acid stone disease, and a raised one does not establish it. Check the urine pH, and read the whole panel with the 24-hour urine stone-risk interpreter.
Frequently asked questions
How do I convert a 24-hour urine uric acid from mg to mmol?
Multiply by 0.00594849, one over the molecular weight 168.11. A 24-hour urate of 600 mg is 3.57 mmol, and the EAU’s 5 mmol/day limit for men is 841 mg/day.
Is urine urate the same as urine uric acid?
Yes — two names for one measurement, as in serum. At urine pH most of it is present as urate salts, and below about pH 5.5 an increasing fraction is undissociated uric acid, which is the poorly soluble form.
What is a normal 24-hour urine uric acid?
Mayo gives 200 to 1,000 mg/24 h for men and 250 to 750 mg/24 h for women; ARUP gives 250 to 750 mg/day without a sex split. Neither publishes an interval for a random sample. The EAU treats above 5 mmol/day in men and above 4 mmol/day in women as a stone risk factor.
Does a normal urine urate exclude uric acid stones?
No. Uric acid stones are driven mainly by a persistently acid urine rather than by the amount of urate excreted, because undissociated uric acid is the insoluble species. Check the urine pH before concluding anything from a normal urate.
Which urine urate test is used in tumour lysis syndrome?
A random urate-to-creatinine ratio, not a 24-hour collection, with a ratio above 1.0 mg/mg recognised as the pattern of acute urate nephropathy. A timed collection is too slow to be useful in that setting.
Related calculators
References
- Mayo Clinic Laboratories. Uric acid, 24 hour, urine (URCU) — reference values. Test catalogue, test ID 614044; 2026.
- ARUP Laboratories. Uric acid, urine — reference interval per 24 hours. Laboratory Test Directory 0020481, component test 0020219; 2026.
- European Association of Urology. EAU Guidelines on Urolithiasis, chapter 4: Metabolic evaluation and recurrence prevention, Table 4.2. EAU Guidelines Office, Arnhem; 2026 edition.
- Coiffier B, Altman A, Pui CH, et al. Guidelines for the management of pediatric and adult tumor lysis syndrome: an evidence-based review. J Clin Oncol. 2008;26(16):2767–2778.
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/