Summary
The computer program EQUIL was designed to calculate relative supersaturations of solute components of common urinary stones. In an extended software version, quantitative consideration of charge balance for a priori or a posteriori pH estimation was added. The reliability of this computation was tested with hydrogen ion titration of buffer solutions containing HEPES [N-(2-hydroxyethyl)piperaizine-N′-ethanesulfonic acid] as well as samples of normal human urine. In the model solutions with HEPES, the difference between calculated pH values and the measured pH was smaller than 1.2% for any titration step within the buffer zone (pH 8.5-6.8). The pH values calculated for whole urine differed from the measured pH by 7% to 53%, and the calculated charge inbalance ranged from 2.6 to 9.6 mM. This net cation inbalance indicates that there is a need to account for other anionic components, including hippurate, amino acids, and isocitrate. In experimental solutions, charge balance calculations with EQUIL can be of great utility because they permit a priori estimation of pH or computation of the composition at a desired pH.
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References
Bergland F, Sorbo B (1960) Turbidimetric analysis of inorganic sulfate in serum, plasma and urine. Scand J Clin Lab Invest 12:147–153
Cannon DC, Olitzky I, Inkpen JA (1974) Proteins. In: Henry RJ, Cannon DC, Winkelmann JW (eds) Clinical chemistry: principles and technics, chapt 16. Harper and Row, Hagerstown New York Evanston San Francisco London, pp 431–447
Chaney AL, Marbach EP (1962) Modified reagents for determination of urea and ammonia. Clin Chem 8:130–132
Davies CW (1962) Ion association. Butterworths, London, p 41
Diem K (1962) Documenta Geigy-Scientific tables, 6th edn. Geigy Pharmaceuticals, Ardsley New York, pp 527–534
Faulkner WR, King JW (1982) Renal function. In: Tietz NW (ed) Fundamentals of clinical chemistry. Saunders, Philadelphia, pp 999–1001
Finlayson B (1977) Calcium stones: some physical and clinical aspects. In: Davis DS (ed) Calcium metabolism in renal failure and nephrolithiasis. Wiley and Sons, New York, pp 337–382
Hodgkinson A, Williams A (1972) An improved colorimetric procedure for urine oxalate. Clin Chim Acta 36:127–132
Natelson S, Pincus JB, Lugovoy JK (1948) Microestimation of citric acid. A new colorimetric reaction for pentabromacetone. J Biol Chem 175:745–750
Neal DG, Purich D, Cannell DS (1984) Osmotic susceptibility and diffusion coefficient of charged bovine serum albumin. J Chem Phys 80:3469–3477
Pak CYC, Skurla C, Harvey J (1985) Graphic display of urinary risk factors for renal stone formation. J Urol 134:867–870
Taussky HH, Shorr E (1953) A microcolorimetric method for the determination of inorganic phosphorus. J Biol Chem 202:675–685
Vega CA, Bates RG (1976) Buffers for the physiological pH range: Thermodynamic constants of four substituted aminoethanesulfonic acids from 5 to 50°C. Anal Chem 48:1293–1296
Werness PG, Brown CM, Smith LH, Finlayson B (1985) EQUIL 2: a BASIC computer program for the calculation of urinary saturation. J Urol 134:1242–1244
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Deceased July 22, 1988
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Ackermann, D., Brown, C., Dunthorn, M. et al. Use of the computer program EQUIL to estimate pH in model solutions and human urine. Urol. Res. 17, 157–161 (1989). https://doi.org/10.1007/BF00256243
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DOI: https://doi.org/10.1007/BF00256243