Diagnostics

Glucose oxidase and hexokinase methods for the determination of serum glucose in the blood

Accurate diagnosis, prescribing treatment require a series of laboratory tests.

The method of determining serum glucose is the most important tool in detecting hyper- and hypoglycemia in patients with diabetes mellitus.

The method allows to adjust the medical therapy data metabolic disorders. Diagnostic glucose levels can also be determined in whole blood and its plasma.

Methods for the determination of blood glucose

Methods for determining the amount of glucose in the blood developed a lot.

Some of them (reductionometric, colorimetric) are practically not used because of the high toxicity and low accuracy of the results.

Most often used enzymatic studies. The glucose oxidase method is a color reaction method that occurs when carbohydrates are heated. Hexokinase determines the activity of blood on hexokinase.

Glucose oxidase method

The glucose oxidase method for determining blood glucose is based on its oxidation reaction under the influence of an enzyme. This forms hydrogen peroxide, it stains the substance Chromogen, the concentration of which determines the amount of glucose.

The glucose oxidase method is used for:

  • hereditary fructose intolerance;
  • pentozurii;
  • lactulose intolerance.

The disadvantage of the study is that hydrogen peroxide is capable of oxidizing both the chromogen and ascorbic, uric acid and bilirubin present in the blood. Calculate the amount of glucose photometric method, the intensity of staining is compared with the calibration graph.

Under laboratory conditions, the level of a substance can be determined:

  1. in venous blood. Automatic analyzers are used;
  2. in capillary blood. The fence is carried out from a finger.

The electrochemical method is to use electrodes containing glucose oxidase. The amount of generated hydrogen peroxide, or the remaining level of oxygen consumed during the oxidation process, is determined.

Diagnostic strips are used at home, they are based on the glucose oxidase-peroxidase reaction, benzidine acts as a chromogen.

Hexokinase method

The hexokinase method is based on a biochemical reaction that allows you to determine the degree of activity of hexokinase in serum.

The substance is the most important enzyme of glucose metabolism, which limits the speed of the process in cells.

Under laboratory conditions, under the action of hexokinase, glucose is phosphorylated by adenosine triphosphate.

As a result of the reaction, organic molecules are formed, the amount of which is determined by the level of light absorption in the ultraviolet zone. Too fast positive hexokinase reaction may also be a sign of the occurrence of malignant tumors.

Preparation for analysis

Blood serum glucose tests are prescribed for:

  • both forms of diabetes for the diagnosis, monitoring of the disease;
  • disorders of the thyroid gland, pituitary;
  • overweight;
  • impaired glucose tolerance.

Before analysis it is necessary to observe a number of conditions so that the results are as reliable as possible:

  1. research is carried out on an empty stomach. Material taken in the morning;
  2. a couple of days before the diagnosis, it is necessary to avoid heavy physical exertion, stress;
  3. In the daily diet of the patient must be at least 150 grams of carbohydrates. With a deficiency, the level of glucose will increase, and it drops slowly, which distorts the analysis data;
  4. the day before the diagnosis can not smoke and drink alcohol;
  5. You can not conduct a study after heavy operations, childbirth, in the presence of inflammation. Contraindicated in the analysis of cirrhosis of the liver, exacerbation of diseases of the stomach, tumor processes;
  6. a couple of days before the study, one should not undergo physiotherapeutic procedures, take oral contraceptives, diuretic drugs, psychotropic drugs, caffeine.
A fasting condition is defined as the interval between meals for at least eight hours. Blood sampling is carried out after a night abstinence from food.

The analysis can give a false positive result in hypokalemia and endocrine diseases (Cushing syndrome, thyrotoxicosis).

Blood serum glucose by age

Normal indicators depend on age:

  • cord blood may contain from 2.5 to 5.3 mmol / l;
  • in premature babies - from 1.1 to 3 mmol / l;
  • children of the first day of life - from 2.22 to 3.33;
  • at the age of 2.7 to 4.4;
  • in children over 6 years of age - from 3.3 to 5.5 mmol / l;
  • in adults up to 60 years - from 4.4 to 6.3;
  • in the elderly - from 4.6 to 6.1 mmol / l.

Hypoglycemia in adults is diagnosed with glucose values ‚Äč‚Äčless than 3.3 mmol / l, and hyperglycemia - more than 6.1 mmol / l.

What does the increase / decrease indicator

Hyperglycemia (rise in blood glucose) is observed when:

  • violation of the hormonal functions of the pituitary gland, thyroid gland: thyrotoxicosis, acromegaly, Cushing's syndrome;
  • illnesses of the pancreas: diabetes, pancreatitis, cystic fibrosis, neoplastic events, hemochromatosis;
  • diseases of the liver, kidneys;
  • disorders of the nervous system: hemorrhages, tumors, brain injuries;
  • poisoning with ether, hydrocyanic acid;
  • with meningitis, epilepsy;
  • heart ailments: myocardial infarction, angina pectoris;
  • vitamin B 1 deficiency;
  • severe burns.

Hypoglycemia occurs in patients with:

  • pancreatic islet tumor, glucagon deficiency;
  • liver damage caused by arsenic poisoning, alcoholic drinks, antihistamine tablets, phosphorus, mercury compounds, benzene, paracetamol;
  • liver ailments when glycogen formation and gluconeogenesis are impaired;
  • endocrine disorders: addison disease, hypothyroidism;
  • diseases of the kidneys, intestines caused by impaired absorption.
Sometimes the level of glucose drops sharply with a large blood loss, dietary disorders, fasting, overdose of insulin, antidiabetic drugs.

Related videos

On the determination of serum glucose in the blood in the video:

Determining the level of glucose is necessary for accurate diagnosis and correction of treatment for diabetes. Hexokinase method of analysis involves the determination of the activity of hexokinase in serum. The glucose oxidase method determines the amount of a substance in a plasma, cerebrospinal fluid.

An analysis is done on an empty stomach. On the eve of the study can not engage in strong physical labor, drink alcohol and smoke. The method consists in studying the reaction of glucose oxidation with the participation of the enzyme glucose oxidase, during which hydrogen peroxide is formed.

Most often, the method is used in endocrinological departments of hospitals. The survey is carried out using an automatic analyzer, photometer. In an emergency, use portable blood glucose meters.

Watch the video: Estimation of Blood Glucose by Glucose Oxidase Method - Amrita University (September 2019).