Web: | mayocliniclabs.com |
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Email: | mcl@mayo.edu |
Telephone: | 800-533-1710 |
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Values are valid only on day of printing. |
Sodium, Potassium, Chloride:
Ion-selective electrode (ISE) (indirect potentiometry). The ISE module performs indirect measurement of electromotive force (EMF). The ISE module measures the EMF difference between an ion-selective electrode and a reference electrode. The EMF of the ion-selective electrode is dependent on the ion concentration of the sample. The EMF of the reference electrode is constant. An electronic calculation circuit converts EMF of the sample to the ion concentration of the sample.(Package insert: Roche Diagnostics ISE reagent; Indianapolis, IN, 2006)
Bicarbonate:
This is a photometric rate reaction. Bicarbonate (HCO3-) reacts with phosphoenolpyruvate (PEP) in the presence of phosphoenolpyruvate carboxylase (PEPC) to produce oxaloacetate and phosphate. The oxaloacetate produced is coupled with NADH in the presence of malate dehydrogenase (MDH) to produce malate and NAD. The consumption of NADH causes a decrease in absorbance and is monitored in the ultraviolet range of 320 to 400 nm. The rate of change is directly proportional to the concentration of bicarbonate.(Package insert: Roche Bicarbonate reagent, Indianapolis, IN, July 2000)
Anion Gap:
This is a calculated result. The following equation is used to calculate the anion gap (A gap):
A gap =Na - (Cl + HCO3)
Blood Urea Nitrogen:
This is a kinetic ultraviolet assay where urease cleaves urea to form ammonia and CO2. The ammonia formed then reacts with a-ketoglutarate and NADH in the presence of urease/glutamate dehydrogenase (GLDH) to yield glutamate and NAD. The decrease in absorbance, due to the consumption of NADH, is measured kinetically and is proportional to the amount of urea in the sample.(Package insert: Roche Urea/BUN reagent; Indianapolis, IN, Sept 2000)
Creatinine:
This enzymatic method is based on the conversion of creatinine with the aid of creatininase, creatinase, and sarcosine oxidase to glycine, formaldehyde, and hydrogen peroxide. Catalyzed by peroxidase the liberated hydrogen peroxide reacts with 4-aminophenazone and HTIB to form a quinone imine chromogen. The color intensity of the quinone imine chromogen formed is directly proportional to the creatinine concentration in the reaction mixture.(Package insert: Roche Diagnostics, Indianapolis IN, 12/2016)
Calcium:
Calcium ions react with 5-nitro-5'-methyl-BAPTA (NM-BAPTA) under alkaline conditions to form a complex. This complex reacts in the second step with EDTA. The change in absorbance is directly proportional to the calcium concentration and is measured photometrically.(Package insert: Roche Calcium Gen.2 reagent, Roche Diagnostic Corp, Indianapolis, IN, 7/2012)
Glucose:
Glucose in the serum, in the presence of hexokinase, is converted to glucose-6-phosphate (G-6-P). In the presence of NADP, oxides G-6-P to gluconate-6-phosphate and NADPH. The rate of NADPH formation is directly proportional to glucose concentration in the serum and is measured photometrically.(Package insert: Roche Glucose Reagent. Indianapolis, IN, January 2000)
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