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Variable Control and Its Influence Before Urine Sample Analysis in a Field Environment.

Author(s): Jiang J, Liu H, Ni W, Zhang M, Gu F, Pei J, Wang Y, Tian Y

Publication: Biopreserv Biobank, 2023, Vol. , Page

PubMed ID: 37590468 PubMed Review Paper? No

Purpose of Paper

Conclusion of Paper

Studies

1. Study Purpose

   This study compared levels of electrolytes (sodium, potassium, and chloride), creatinine, urea, gamma-glutamyl transpeptidase (GGT), myoglobulin, and microalbumin between matched centrifuged and uncentrifuged urine that was stored for up to 55 days at 4°C, among matched urine specimens stored at -40, 4, 20 or 50°C, and among urine stored at 4°C under low (10-15%), medium (40-60%) and high (80-90%) humidity.  Urine was collected from ten healthy volunteers (5 men and 5 women, 25-31 years of age). Urine was divided and mixed with a standard, centrifuged at 4500 rpm for 20 min or left unprocessed, and aliquoted for storage. Aliquots were stored for 0 h, 4 h, 24 h, 72 h, 7 days, or 55 days at -40, 4, 20 and 50°C at 45-55% humidity or at 4°C at a humidity of 10-15% (low), 40-60% (medium) or 80-90% (high humidity). Electrolytes (sodium, potassium, and chloride) levels were quantified by an ion selective electrode. GGT and creatinine levels were measured by enzyme colorimetry. Urine myoglobulin and microalbumin concentrations were analyzed using fluorescence immunochromatography.

   Summary of Findings:

   Compared to urine stored after centrifugation, stored uncentrifuged urine had higher levels of GGT after 4 h to 7 days (P<0.05), and lower myoglobulin levels after 1 h, 24 h, and 55 days; but, GGT and myoglobulin levels were comparable at the other storage timepoints examined. Centrifugation prior to storage had no effect on electrolyte, urea, creatinine or microalbumin levels. In general, changes in analyte levels occurred fastest when storage was at -40°C followed by 50°C. When stored at -40°C, significant declines in GGT, creatinine, and potassium occurred at ≥2 h, declines in sodium and chloride occurred at ≥4 h, and urea concentrations increased after 55 days. Storage at 4°C led to significant declines in GGT at 4 h, chloride at 72 h and 7 days, and a significant increase in sodium at 7 days. Storage at 20°C led to significant declines in GGT at ≥4 h, chloride at 72 h and 55 days, and significant increases in sodium at 7 days. Storage at 50°C led to increased potassium at 4 h, increased chloride at 4 h –7 days, increased creatinine at 4 h, 72 h, and 7 days, increased sodium at 24 h and 7 days, and a significant decrease in GGT at ≥24 h. Myoglobulin was stable in urine that was stored for 4 h at 4°C, but changes were noted at the other temperatures. Analytes were generally most stable when urine was stored at 4°C under dry conditions (low humidity, 10-25%). Under low humidity, significant increases in sodium occurred after 24 h and ≥7 days, chloride after ≥7 days, potassium after 55 days, decreased creatinine at ≥24 h, and decreased GGT after ≥4 h, but no change in urea or microalbumin levels were observed with urine storage under low humidity.  Storage at 40-60% humidity led to increased sodium after ≥7 days, decreased chloride at 72 h, and decreased GGT after 72 h, but had no effect on levels of potassium, creatinine, urea, or microalbumin. Storage under high humidity (80-90%) resulted in increased sodium after ≥4 h, potassium after ≥24 h, chloride after 4 h and 7 days, and creatinine and GGT after ≥24 h and decreased urea after ≥7 days and decreased myoglobulin after 4 h. Importantly, significant effects of humidity on the levels of each analyte were observed at one or more timepoints.

   Biospecimens

   • Bodily Fluid - Urine

   Preservative Types

   • None (Fresh)
   • Frozen

   Diagnoses:

   • Normal

   Platform:

   Analyte	Technology Platform
   Protein	Clinical chemistry/auto analyzer
   Electrolyte/Metal	Ion selective electrode
   Small molecule	Colorimetric assay
   Small molecule	Clinical chemistry/auto analyzer
   Protein	Colorimetric assay

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Biospecimen Aliquots and Components	Centrifugation	Centrifuged Not centrifuged
   Storage	Storage conditions	Low humidity (10-15%) Medium humidity (40-60%) High humidity (80-90%) Centrifuged Uncentrifuged
   Storage	Storage temperature	-40°C 4°C 20°C 50°C
   Storage	Storage duration	0 h 2 h 4 h 24 h 72 h 7 days 55 days

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