Effect of storage duration and analyte concentration on measurement of neutral pH clinical chemistry urine analytes

Chapal Debnath, Niral Savaliya


Background: The aim of the study was focused very keenly in measuring the changes in concentration of sodium, potassium and creatinine in urine, stored for 60 days effect of urinary storage duration of clinical chemistry analytes. This study determined whether patient urine samples can be used for day to day urine quality control.

Methods: Spot urine samples were collected from left over samples from the admitted patients in various hospital wards. The samples are kept which its pH was unaltered or unspiked and was aliquoted and deep fridged immediately. These aliquots were melted at an incubator temperature of 86 ºC and was analyzed in the analyzer for 60 days and data were collected for checking variations.

Results: With the strenous and continious monitoring from the side of the researchers, the researchers had throughly analysed and found that in both the sets almost all of those analysed urine test of pH 5 and analytes remained very much stable for a period of 60 days which could be used for running daily internal quality controls.

Conclusions: Patient urine can be used as internal quality control sample for at least 60 days for sodium, potassium and creatinine. During the 60 days period, there is no appreciable degradation of any of the two sets of samples for sodium, potassium and creatinine measurements.


pH, Sodium, potassium and creatinine standard deviation, Coefficient of variation, Quality control

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Prochaska M, Taylor E, Ferraro PM, Curhan G. Relative Supersaturation of 24-hour Urine and Likelihood of Kidney Stones. J Urol. 2018;199(5):1262-6.

Lee HL, Simon EE. Roles and mechanisms of urinary buffer excretion. Am J Physiol. 1987;253:595-605.

Rosen S, Stillman IE. Acute tubular necrosis is a syndrome of physiologic and pathologic dissociation. J Am Soc Nephrol. 2008;19(5):871-5.

Salvetti A, Ghiadoni L. Thiazide diuretics in the treatment of hypertension: an update. J Am Soc Nephrol. 2006;17:25-9.

Larsson LE, Ohman S. Quality assurance in urine analysis. Quality Assuran Health Care. 1992;4(2):141-9.

Ng RH, Menon M, Ladenson JH. Collection and Handling of 24-hour urine specimens for measurement of analytes related to renal calculi. Clinic Chem. 1984;30(3).

Juncos LI, Juncos LA. Prerenal azotemia. Clinic Dec Nephrol Hypertens Kidney Transplant. 2018:175-82.

Geerse. Phosphate, the forgotten electrolyte. Bartex.USMP/MG144/16-0004a(3) 05/18. Critical Care 2010, 14:R147

White GA. Implementation of an automated system for the detection of acute kidney injury in a district general hospital and its impact on patient outcomes. Pract Diabet. 2015;32(4):129-33.

Gunn-Christie RG, Flatland B, Friedrichs KR, Szladovits B, Harr KE, Ruotsalo K, et al. ASVCP quality assurance guidelines: control of preanalytical, analytical, and postanalytical factors for urinalysis, cytology, and clinical chemistry in veterinary laboratories. Vet Clin Pathol. 2012;41(1):18-26.

Donadio C, Moriconi D, Berta R, Anselmino M. Estimation of urinary creatinine excretion and prediction of renal function in morbidly obese patients: new tools from body composition analysis. Kidney Blood Press Res. 2017;42(4):629-40.

Micco LD, Quinn RR, Ronksley PE, Bellizzi V, Lewin AM, Cianciaruso B, et al. Urine creatinine excretion and clinical outcomes in CKD. Clin J Am Soc Nephrol. 2013;8(11):1877-83.

James GD, Sealey JE, Alderman M, Ljungman S, Mueller FB, Pecker MS, et al. A longitudinal study of urinary creatinine and creatinine clearance in normal subjects race, sex, and age differences. Am J Hypertens. 1988;1(2):124.

Barbaresi G, Gozzo ML, Zuppi C. Automation in urinalysis: sample and data management, and quality control. J Clinic Lab Automat. 1986;8(3):142-6.

Winter SD. Measurement of urine electrolytes: clinical significance and methods. Critic Rev Clinic Lab Sci. 1981.

Mentrasti G, Scortichini L, Torniai M, Giampieri R, Morgese F, Rinaldi S, et. al. Syndrome of inappropriate antidiuretic hormone secretion (SIADH): optimal management. Ther Clin Risk Manag. 2020;16:663-72.

Ganguly S. World Federation of Societies of Anesthesiologists. TOTW 314 – Hyponatraemia (2nd April 2015). Available at: Accessed on 23 September 2021.

Kovesdy CP. Management of hyperkalaemia in chronic kidney disease. Nat Rev Nephrol. 2014;10(11):659-62.

Hyperkalemia, a chronic risk for CKD patients and a potential barrier to recommended CKD Treatment. National Kidney Foundation. New York: Relypsa.

Lehnhardt A, Kemper MJ. Pathogenesis, diagnosis and management of hyperkalemia. Pediatr Nephrol. 2011;26(3):377-84.