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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.(2,3) 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.(2)
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(4) 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.
Urinary sulfate can be used to assess the nutrition intake of animal protein.
It also can be a reflection of protein intake and can be assessed in patients with stone disease as related to stone supersaturation and prevention of stone disease.
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.
No significant cautionary statements
1. 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
2. Tschope W, Ritz E: Sulfur-containing amino acids are a major determinant of urinary calcium. Miner Electrolyte Metab 1985;11:137-139
3. Puche RC, Vacarro D, Sanchez A, et al: Increased fractional excretion of sulphate in stone formers. Br J Urol 1993;71:523-526
4. Parks JH, Coward M, Coe FL: Correspondence between stone composition and urine supersaturation in nephrolithiasis. Kidney Int 1997;51:894-900