Urine Chloride Unit Converter
Urine Chloride Unit Converter
In a metabolic alkalosis the urine chloride, not the urine sodium, shows whether chloride depletion is the cause. Convert mmol/L, mEq/L, mg/dL and mg/L.
Urine Chloride converter
Monovalent — mmol/L = mEq/LSpot urine chloride 12 mmol/L in a metabolic alkalosis, no diuretic for a week
Formula and conversion factors
mg/dL = mmol/L ÷ 0.282087
mEq/L = mmol/L (chloride is monovalent)
- 0.282087
- derived from the atomic weight of chlorine, 35.45 — IUPAC publishes an interval of 35.446 to 35.457 rather than a single value, and 35.45 is the conventional figure inside it
- 20 and 25 mmol/L
- the two published cut-offs below which a metabolic alkalosis is chloride-responsive: Merck gives 20, Rose and Post 25
- diuretics
- a loop or thiazide diuretic still acting raises the urine chloride whatever the chloride status, so the test must wait
Worked example
Spot urine chloride 12 mmol/L in a metabolic alkalosis, no diuretic for a week
12.0 mmol/L — and 12.0 mEq/L, the same number
12 ÷ 0.282087 = 42.5 mg/dL = 425 mg/L
Below 20 mmol/L on Merck's cut-off and below 25 on Rose and Post's, so chloride-responsive on both
Chloride depletion from vomiting, gastric drainage or a diuretic that has worn off: replacing chloride lets the kidney excrete the excess bicarbonate
Spot urine chloride converted
| mmol/L (mEq/L) | mg/dL | mg/L |
|---|---|---|
| 10.0 | 35.5 | 355 |
| 20.0 | 70.9 | 709 |
| 25.0 | 88.6 | 886 |
| 40.0 | 141.8 | 1,418 |
| 100.0 | 354.5 | 3,545 |
Cut-offs and intervals in print
| Source and basis | Figure | Unit |
|---|---|---|
| Merck Manual, spot, chloride-responsive alkalosis | Below 20 | mmol/L |
| Rose and Post, spot, chloride depletion | Below 25 | mmol/L |
| Mayo CLU, 24-hour, adults 18 and over | 34 – 286 | mmol/24 h |
| ARUP ULYTE, 24-hour collection | 140 – 250 | mmol/day |
| Mayo, random urine chloride (RCHLU) | No established reference values | — |
Why urine chloride and not urine sodium
Urine chloride is the one urine electrolyte with a sharp, well-defined use: it sorts a metabolic alkalosis into chloride-responsive and chloride-resistant. The reason it, and not the urine sodium, is the test is worth understanding. In vomiting or nasogastric suction the kidney is chloride-depleted and holds chloride back, but it must still excrete the excess bicarbonate, and bicarbonate leaves as a sodium salt. So the urine sodium can be high while the patient is profoundly volume- and chloride-depleted. The urine chloride is not fooled by that. The full decision, with the blood pressure and the diuretic history, is on the metabolic alkalosis urine chloride interpreter.
Chloride is monovalent, so mmol/L and mEq/L are identical, and mg/dL is mmol/L divided by 0.282087 — the factor derived from the atomic weight 35.45, the same one the serum chloride converter uses. Mass units never appear on a urine chloride report and are offered only for older literature.
The cut-offs disagree, and the disagreement is small but real. The Merck Manual splits at 20 mmol/L; Rose and Post’s textbook treats below 25 mmol/L as the sign of chloride depletion. Below 20 the answer is chloride-responsive; above 25 it is chloride-resistant; in between, the history carries the weight. One caveat dominates both: a loop or thiazide diuretic makes the kidney excrete chloride for as long as it acts, so a urine chloride taken within a day or two of a dose is high even in a chloride-depleted patient and classifies nothing. Repeat it once the drug has worn off.
On a 24-hour collection the picture changes entirely. Mayo gives 34 to 286 mmol/24 h and ARUP 140 to 250 mmol/day, and those intervals describe dietary salt intake, not acid-base handling — chloride and sodium are eaten together as sodium chloride. A spot concentration cannot be converted into a daily excretion without the collection volume, and the alkalosis cut-offs do not transfer to the timed figure at all.
Frequently asked questions
Is urine chloride in mmol/L the same as mEq/L?
Yes. Chloride carries one negative charge, so one millimole is one milliequivalent and the two figures are interchangeable.
What urine chloride means a chloride-responsive alkalosis?
Below 20 mmol/L on the Merck Manual’s cut-off, or below 25 mmol/L on Rose and Post’s. Either way the kidney is conserving chloride, so the body is chloride-depleted — vomiting, nasogastric drainage, or a diuretic that is no longer acting.
Why not use the urine sodium instead?
Because the kidney must excrete the excess bicarbonate of an alkalosis, and bicarbonate leaves paired with sodium. The urine sodium can therefore be high in a patient who is severely chloride- and volume-depleted. The urine chloride is the measurement that is not misled.
How do I convert urine chloride to mg/dL?
Divide the mmol/L figure by 0.282087, derived from chlorine’s atomic weight of 35.45. A urine chloride of 12 mmol/L is 42.5 mg/dL. No laboratory reports a urine chloride in mass units.
Do the alkalosis cut-offs apply to a 24-hour collection?
No. They are concentrations on a spot sample. A 24-hour chloride is an amount — Mayo gives 34 to 286 mmol/24 h — and it chiefly reflects dietary salt. The two cannot be related without the collection volume.
Related calculators
References
- Lewis JL III. Metabolic alkalosis. Merck Manual Professional Edition. Revised March 2025.
- Rose BD, Post TW. Clinical Physiology of Acid-Base and Electrolyte Disorders. 5th ed. McGraw-Hill; 2001:551–558.
- Mayo Clinic Laboratories. Chloride, 24 hour, urine (CLU) — reference values. Test catalogue, test ID 614058; 2026.
- ARUP Laboratories. Electrolytes, urine (ULYTE) — reference intervals for sodium, potassium and chloride per 24 hours. Laboratory Test Directory 0020498; 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/