Blood Chemical Analysis

The human body is made up of a complex mixture of cells and chemical compounds that are present in different concentrations. Alterations of these concentrations may lead to disease. In order to analyze the makeup and concentrations of chemicals in the blood, clinical chemistry laboratories use a variety analyzers and principles of chemistry.

• Chemistry laboratories analyze blood using a variety of techniques.

Clinical Chemistry

• The clinical chemistry laboratory is equipped to analyze the chemical properties of blood. Blood contains different chemicals that are essential to the functioning of the body. These chemicals include proteins, enzymes, vitamins, minerals, lipids (fats) and sugars. Several techniques are used to measure these chemicals in the blood.

Turbidometry

• Turbidometry uses the principle of light absorption to measure the concentration of chemicals in the substance. When plasma or serum from the blood is mixed with certain reagents, the ensuing chemical reaction creates turbidity, or cloudiness, in the sample. Turbidity is measured by the amount of light that is allowed to pass through the sample. The greater the concentration of the chemical being analyzed, the greater the turbidity and the lower the amount of light that passes freely through the sample.

Colorimetry

• Colorimetry works much in the same way that turbidometry works. The difference is that colorimetry analyzers look for a change in the color of the sample after a reagent is added to the sample. The degree of color change is directly proportional to the concentration of the chemical being analyzed in the sample. So the more chemical present in the sample, the greater the change in color that will be detected by the analyzer.

Immunology

• Immunology consists of using antibodies aimed specifically at certain chemicals to detect those chemicals. However, antibodies are only useful in detecting large molecules like proteins or hormones. The antibodies used in clinical chemistry are usually labeled with a radioisotope or an enzyme. After adding the antibodies to the sample, excess antibody is removed. Whatever antibodies attached to the chemical being analyzed will be detected through the attached label.

Chromatography

• Chromatography analyzers measure the concentration and makeup of chemical compounds by passing the sample being analyzed through a column (usually paper or a gas). As the sample passes through the column, the different chemicals that make up the sample are separated. The separated chemicals are then identified by their size and shape in the column. Many tests for illegal drugs in urine and blood are based on this principle.