Reagents and Methods of Use With Automated Analyzers For Obtaining A Specific Gravity Index For Urine

An assay method for obtaining a Specific Gravity Index for a biological sample, the method comprising:

• reacting the biological sample with a first reagent comprising o-nitrophenylgalactoside;
• then reacting the biological sample with a second reagent comprising β-galactosidase, such that the β-galactosidase is converted to yellow o-nitrophenol in an amount that is in direct relation to the amount of sodium and potassium present in the biological sample;
• analyzing the yellow color of the reacted biological sample with a spectrophotometer;
• obtaining a measure of light absorbance for the reacted biological sample;
• and
• calculating a specific gravity index based on the light absorbance measurement.

A kit for measuring the amount of total sodium and potassium in a biological sample, the kit comprising:

• a first reagent comprising o-nitrophenylgalactoside;
• and
• a second reagent comprising β-galactosidase that, in the presence of the sodium and potassium in the biological sample, will cleave the o-nitrophenylgalactoside into o-nitrophenol producing a yellow color in the biological sample;
• such that the sample, when analyzed spectrophotometrically, can provide a Specific gravity Index indicative of the amount of total sodium and potassium in the biological sample.