HOME > Outline of the Myoinositol (MI) > Reagent Features and Performance

Reagents for the Measurement of Myoinositol (MI) Lucica MI

Reagent Features and Performance

(1) Reagent features

Lucica® MI is an in vitro diagnostic test kit for the measurement of UMI before and after glucose loading.

Measurement of UMI requires a urine sample, but no blood sample is needed. This test may thus be suitable for mass screening for both diabetes and glucose intolerance.

Lucica® MI is a highly sensitive test kit based on an enzymatic method that uses liquid reagents requiring no preparation.

Lucica® MI can be used in general-purpose biochemical autoanalyzers.

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(2) Assay Principle: Enzymatic cycling method

Myoinosose is formed from MI by reaction with myoinositol dehydrogenase (MIDH). At the same time, thio-NADH is formed from the coenzyme thio-NAD. Through the same reaction with MIDH, using NADH as a coenzyme, MI is formed from myoinosose. This is used again in the prior reaction (enzyme cycling). The rate of increase in thio-NADH, dependent on MI concentration, is measured by absorbance changes at a wavelength of 405 nm. This quantifies the concentration of MI.


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(3) Mesurement range

The measurement range for UMI is 10-1500μM.


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(4) Assay Precision

Within-run
  Urine-1 Urine-2 Urine-3
Mean (μM) 104.2 351.9 1086.8
CV (%) 1.1 0.7 0.5

Between-run
  Urine-1 Urine-2 Urine-3
Mean (μM) 105.8 352.1 1084.9
CV (%) 1.3 0.4 0.6

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(5) Substrate specificity

Substrate Relative activity %
Myoinositol 100
D-chiroinositol 18
Glucose 0
Sorbitol 0
Fructose 0
1,5 Anhydroglucitol 0
Galactose 0
Mannose 0
Mannitol 0

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(6) Interfering substances

Substance Concentration range with no effect on assay value
Ascorbic acid ~500mg/dL
Oxalic acid ~500mg/dL
Tartalic acid ~500mg/dL
Sodium tricitrate ~500mg/dL
Ammonium chloride ~500mg/dL
Creatinine ~500mg/dL
Urea ~500mg/dL
Galactose ~50mg/dL
Uric acid ~50mg/dL
Glucose ~2g/dL
Hemolyzed hemoglobin ~96.8mg/dL

Glucose at concentrations > 2g/dL can cause false-negative errors. Creatinine at concentrations exceeding 500mg/dL can cause false-positive errors.


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(7) Linearity

This figure shows the dilution linearity of 4 different urine samples. In all case, good linearity was shown.


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(8) Assay Examples

(7170s Hitachi chemistry analyzer)


(Reaction Curve: Hitachi 7170s)

 

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