JPH0245827B2 - KUREACHININSOKUTEIYOSHAKUSOSEIBUTSU - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a reagent composition for quantitatively measuring creatinine in body fluids. Creatinine is produced by non-enzymatic dehydration of creatine, which is produced from creatine phosphate, which is one of the energy sources for muscle contraction, and is not utilized at all in the body and is released into the urine as a final metabolite. Excreted. Measurement of creatinine provides meaningful information for diagnosis of renal disorders such as nephritis and renal failure, muscular dystrophy, and observation of the progress of treatment. A widely used method for measuring creatinine in body fluids is the Jacques method, in which picric acid and the active methylene group of creatinine are subjected to a condensation reaction under alkaline conditions, and the resulting color is measured colorimetrically. However, since this measurement method involves a reaction between picric acid and active methylene of creatinine, it is not specific for creatinine, and other active methylene group-containing substances in serum such as acetoacetic acid and oxybutyric acid exhibit similar color reactions. This causes a positive error. Therefore, in order to eliminate the interference of interfering substances such as proteins present in serum, a protein removal procedure was required. However, the protein removal procedure is complicated and is not suitable for clinical testing methods that require speed. Not. Therefore, surfactants have come to be used as a method for suppressing interference with proteins and the like without requiring a protein removal operation. Conventionally, as this surfactant, an ionic higher alcohol sulfate ester or a nonionic polyoxyethylene oxide condensation type is used. In particular, lauryl sulfate is widely used, but it tends to precipitate and precipitate during low-temperature storage in winter or during measurement, resulting in a cloudy reagent, which has been a major drawback. In view of the above points, the present inventors investigated various surfactants, and as a result, they discovered a stable reagent for measuring creatinine that can solve the conventional drawbacks by using decyl sulfate, and completed the present invention. The present invention consists of an alkaline reagent system, a picric acid reagent system, an acidic solution, and a standard reagent system. As the alkaline reagent system, for example, borax and sodium hydroxide or its potassium salt are used. The picric acid test solution system uses picric acid, decyl sulfate as main components such as sodium, potassium, or lithium, and sodium hydroxide or its potassium. The acidic solution is preferably an acidic substance that can change the pH to the acidic side. For example, acetic acid, hydrochloric acid, sulfuric acid, nitric acid, etc. are used. The standard test solution system used is creatinine, hydrochloric acid, etc. According to the present invention, no precipitation of crystals is observed at decyl sulfate concentrations of 0 to 6% during ice-cooling and refrigerator storage (16 days at minus 1°C to 3°C). No crystal precipitation was observed even in a 1:1 mixture of picric acid test solution and alkaline test solution under similar concentration and storage conditions. Precipitation is observed in the conventional picric acid test solution system containing lauryl sulfate under these storage conditions. Table 1 shows a comparison of the concentration of sodium decyl sulfate in a picric acid test solution and a mixed solution (measurement solution) in which an alkaline test solution is added to the concentration of sodium lauryl sulfate in the presence of precipitation/precipitation.

[Table] Compared to conventional reagent systems using lauryl sulfate, the reagent for creatinine measurement of the present invention prevents reagent precipitation and precipitation in low-temperature conditions in winter, making it extremely safe, simple, and accurate for creatinine measurement. It provides: The present invention will be explained below with reference to Examples. Example 1 (1) Preparation of reagent Creatinine alkaline test solution Add and dissolve 8.35 g of sodium hydroxide and 22.06 g of borax in approximately 800 ml of water, and adjust the total volume to 1000 ml with water. Creatinine picric acid test solution Add and dissolve 1.06 g of sodium hydroxide and 7.10 g of picric acid in approximately 800 ml of water, then add 25.0 g of sodium decyl sulfate,
Adjust the total volume to 1000ml with water. Creatinine acid solution Dissolve 800 ml of glacial acetic acid in 1000 ml of water. Creatinine standard solution Dissolve 0.05 g of creatinine and 9.0 ml of hydrochloric acid in approximately 800 ml of water, and adjust the total volume to 1000 ml with water. (2) Measurement procedure When using as a measurement reagent, mix 1:1 of creatinine alkaline test solution and 1:1 creatinine picric acid test solution.
Mix in a ratio of 1 part. Take 0.2 ml each of serum or 10-fold diluted urine (use 24-hour urine) for the specimen, pure water for the reagent blank, and standard solution in test tubes. Then,
Add 3.0 ml of measurement reagent to each, mix and leave at room temperature for 30 to 35 minutes. After standing, read the absorbance of the sample ( ) and standard solution at 510 nm using the reagent blank as a reference, and return the sample and reagent blanks to the test tube. Within 30 minutes after reading the absorbance, add 3 drops of creatinine acetate test solution, mix, and leave at room temperature for 10 minutes. After standing, test the sample at 510nm using the reagent blank as a control ()
Measure the absorbance within 50 minutes. Then, calculate the creatinine concentration using the following formula. <Formula> Serum creatinine (mg/dl) = sample ()
OD - OD of sample ()/OD of standard solution x 5

[Brief explanation of the drawing]

FIG. 1 is a graph showing the correlation between the reagent of the present invention and the reagent of the conventional method.

Claims (1)

[Claims] 1. A reagent composition for measuring creatinine in body fluids, which uses decyl sulfate as a surfactant in a reagent system consisting of an alkaline reagent system, a picric acid reagent system, and an acidic solution.