Annual Checkup for Food Handlers, Basic

The ESR test measures the rate at which red blood cells (erythrocytes) settle (sediment) at the bottom of a tube that contains a blood sample in one hour. The test result is expressed in millimeters per hour (mm/hr).

In the presence of inflammation, certain proteins mainly fibrinogen increase in blood. This high proportion of fibrinogen in the blood causes the red blood cells to form a stack (rouleaux formation) which settle quickly due to their high density.

The ESR test is a non-specific measure of inflammation. An ESR can be affected by conditions other than inflammation also. Although a high ESR can detect the presence of inflammation, it cannot provide any information regarding the cause and site of inflammation. Hence, an ESR test is done along with other tests.

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Blood Stag is composed of blood cells suspended in blood plasma (yellowish-colored liquid). The blood cells include red blood cells (also called RBCs or erythrocytes), white blood cells (also called WBCs or leukocytes), and platelets (also called thrombocytes).

Red blood cells (RBCs) are the most abundant blood cells. RBCs contain hemoglobin which helps in the transportation of oxygen to the tissues. RBC count is the measurement of the number of RBCs in a given volume of blood.

Packed Cell Volume (PCV) or Hematocrit (Hct) is the measurement of the blood volume occupied by RBCs. It is expressed in percentage.

White blood cells (WBCs) are key components of the immune system and thus protect the body from various infections and cancers. Total Leucocyte count (TLC) is the measurement of the total number of leukocytes (WBCs) in a given volume of blood.

There are five types of WBCs:

1. Neutrophils

2. Basophils

3. Eosinophils

4. Lymphocytes

5. Monocytes

Differential Leucocyte Count (DLC) determines the percentage of different types of WBCs.

Neutrophils, Basophils, and Eosinophils are called Granulocytes because of the presence of granules inside these cells.

Absolute count of different types of WBCs is the measurement of their absolute numbers in the given volume of blood.

Platelet count - Platelets (also called thrombocytes) are disc-shaped cell fragments without a nucleus that help in blood clotting. Platelet count is the measurement of the number of platelets in a given volume of blood.

Mean Platelet Volume (MPV) is a measurement of the average size of platelets.

PDW or platelet distribution width refers to the variation of platelet size distribution

Hemoglobin (Hb) -  Hemoglobin (Hb) is a protein found in red blood cells (RBCs) that carries oxygen from the lungs to the body tissues, exchanges the oxygen for carbon dioxide, and then carries the carbon dioxide back to the lungs where it is exchanged for oxygen.

Mean Corpuscular Volume (MCV) is the average volume of a red blood cell.

Mean Corpuscular Hemoglobin (MCH) is the average amount of hemoglobin in the average red blood cell.

Mean Corpuscular Hemoglobin Concentration (MCHC) is the average concentration of hemoglobin in a given volume of red cells.

Red Cell Distribution Width Coefficient of variation (RDW CV)is a measurement of the variability of the red blood distribution curve and their mean size. 

The stool examination R/M (routine microscopy) is done by taking concentrated sediment of fresh or formalin preserved stool followed by drying the slide to make the specimen dry. It is then fixed with the reagents and stained with different stains. After the staining procedure is completed, the slide is examined under the microscope at different fields to identify protozoan trophozoites and cysts and for confirmation of any other species.  Depending upon what species is present, the reporting of the stool slide is made.

The Widal test measures the titres of antibody against the bacteria which cause Enteric fever.

Typhoid and paratyphoid fever are generally acquired when you consume food or water, contaminated by feces of an acutely infected or convalescent person (recovering from disease) or a chronic, asymptomatic carrier. The incubation period (the time interval between exposure to an infection and the appearance of the first symptoms) of Enteric fever is 6-30 days. Paratyphoid fever is similar but often less severe than typhoid fever.

Widal test is an agglutination test to detect antibodies (agglutinins) in a blood sample against two antigens (O & H) of bacteria, Salmonella enterica. Agglutination refers to the visible clumping of particles when a particulate antigen combines with its antibody in the presence of optimum conditions for antigen-antibody reaction. When this test is performed on a slide, it is called Slide agglutination and when it is carried out in a test tube,  it is called Tube agglutination. Widal test by Tube agglutination is recommended over Slide agglutination method. The antigens used in the test are “H” and “O” antigens of Salmonella Typhi and “H” antigen of S. Paratyphi.

Widal test should only be performed after the first week. The reason being the antibody against “O” and “H” antigens of Salmonella start appearing in serum at the end of the first week of fever. It is preferable to test two blood samples at an interval of 7 to 10 days to demonstrate rising antibody titres.

Urine Routine and Microscopy test involve the three-part evaluation of the urine sample.

1. Gross Examination - It involves the visual examination of the urine sample for color and appearance.

2. Chemical Examination - It is done by urine dip-stick method which involves the use of reagent test strips. These test strips are dipped into the urine sample and the colors that develop are matched with the control for analysis. It is done to examine the urine sample for glucose, protein, pH, specific gravity, blood, nitrites, ketones, leukocyte esterase, bilirubin, and urobilinogen.

3. Microscopic Examination - It involves the examination of the urine sample under the microscope for casts, crystals, cells, bacteria, and yeast.