SULFU - Clinical: Sulfate, 24 Hour, Urine

Test Catalog

Test Name

Test ID: SULFU    
Sulfate, 24 Hour, Urine

Useful For Suggests clinical disorders or settings where the test may be helpful

Assessing the nutrition intake of animal protein


The calculation of urinary supersaturation of various crystals or stones

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Urinary sulfate is a reflection of dietary protein intake, particularly meat, fish, and poultry, which are rich in sulfur-containing amino acids methionine and cysteine. Urinary sulfate can be used to assess dietary protein intake for nutritional purposes. A protein-rich diet has been associated with an increased risk for stone formation, possibly due, in part, to an increase in urinary calcium excretion caused by acid production from metabolism of sulfur-containing amino acids.(1,2) Indeed, urinary sulfate excretion is higher in patients who have kidney stones than in individuals who do not form stones. Thus, urinary sulfate excretion may provide an index for protein-induced calciuria.(1)


Sulfate is a major anion in the urine that has significant affinity for cations and modulates the availability of cations for reacting with other anions in the urine. It thus is an important factor of urinary supersaturation(3) for various crystals or stones such as calcium oxalate, hydroxyapatite, and brushite. For example, a high sulfate concentration may modulate the availability of calcium for reacting with oxalate and thus affect the propensity for calcium oxalate stone or crystal formation. Urinary sulfate also has a major impact on buffering or providing hydrogen ions and as such modulates the supersaturation of uric acid.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

7-47 mmol/24 hours

Interpretation Provides information to assist in interpretation of the test results

Urinary sulfate is a reflection of dietary protein intake, particularly of meat, and thus can be used as an index of nutritional protein intake.


It also is used in the calculation of urinary supersaturation of various crystals or stones.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

No significant cautionary statements

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Tschope W, Ritz E: Sulfur-containing amino acids are a major determinant of urinary calcium. Miner Electrolyte Metab 1985;11:137-139

2. Puche RC, Vacarro D, Sanchez A, et al: Increased fractional excretion of sulphate in stone formers. Br J Urol 1993;71:523-526

3. Parks JH, Coward M, Coe FL: Correspondence between stone composition and urine supersaturation in nephrolithiasis. Kidney Int 1997;51:894-900

4. Houterman S, van Faassen A, Ocke MC, et al: Is urinary sulfate a biomarker for the intake of animal protein and meat? Cancer Lett 1997;114:295-296

Special Instructions and Forms Library of PDFs including pertinent information and consent forms, specimen collection and preparation information, test algorithms, and other information pertinent to test