Common Blood Tests - A Review

Introduction

Blood tests are commonly prescribed to aid doctors in making a diagnosis. Often, they are crucial for a definitive diagnosis. The tests generally provide a detailed picture of the organ functioning and if there is any internal disease or deficiency. The various tests are important to evaluate the components in blood, like proteins, enzymes, and blood cells. They are an irreplaceable part of medicine. Having all results normal indicates overall well-being. Some blood tests are done in routine examinations to assess fitness.

What Are the Common Blood Tests Done?

Complete Blood Count (CBC): This is the most commonly prescribed test by doctors to gain insight into the blood components. Blood components tested are

• Red Blood Cells: Determines the amount of circulating red blood cells in the body. Any abnormalities are noted.

• White Blood Cells: The levels determine the ability of the body to defend itself against infections and inflammation. The cells account for a major part of the first line of defense in case of injury or infection.

• Platelets: This test helps reveal the body's ability to clot.

• Hemoglobin: It is the measure of hemoglobin, the protein present in the body responsible for carrying oxygen to the cells as per their need. Reduced hemoglobin means the individual is anemic and needs further diagnosis and treatment.

• Hematocrit: It measures the volume of red blood cells relative to total blood volume, expressed as a percentage.

• Mean Corpuscular Volume: They provide information about the average size and volume of red blood cells. This test can diagnose the type of anemia. Suppose the red cells appear smaller than normal. In that case, they are suggestive of iron deficiency anemia and thalassemia, and when the red cells appear larger than normal, they are suggestive of pernicious anemia.

This is the preliminary test doctors conduct when they want to know more about the disease. Disorders like anemia, leukemia, infections, and clotting diseases can be diagnosed with the help of these.

Lipid Profile: The body's total cholesterol levels and triglycerides are measured. It signifies cardiovascular health and disease if present. The tests in this profile assess the following:

• Total Cholesterol.

• Low-Density Lipoprotein: The presence of this is called bad cholesterol.

• High-Density Lipoprotein: This protein is called good cholesterol.

• Triglycerides: When there is an increase in triglycerides, they are associated with an increased cardiovascular risk.

Thyroid Function Test: Measurements of hormones thyroxine (T4) and triiodothyronine (T3) levels are done to check the thyroid gland and its functioning. If the values are not in the normal range, there is a higher chance of metabolic issues. The assessments included in thyroid function tests include:

• Thyroid Stimulating Hormone: This is a regulator hormone secreted by the anterior pituitary gland—an increase in these hormone levels shows hypothyroidism. Low levels of thyroid stimulating hormone indicate hyperthyroidism.

• Thyroxine and Triiodothyronine: These hormones measure the value of thyroid hormones in the body. Abnormalities in the hormone levels indicate dysfunction in the thyroid or pituitary gland.

• Thyroid Antibodies: Antibodies are tested to detect autoimmune disorders. These autoantibodies attack the thyroid gland and lead to disorders like Hashimoto’s thyroiditis.

Coagulation Profile: These tests are conducted to assess blood clotting function. Abnormalities help in diagnosing bleeding and clotting disorders.

• Prothrombin Time: Prothrombin is one of the important proteins involved in blood clotting. Normal prothrombin time is 10 to 14 seconds.

• International Normalized Ratio: This test gives a ratio of the time needed to form a clot. The normal range is 1.0 to 1.2.

• Total Platelet count: Normal range is 150000 to 400000.

• Activated Partial Thromboplastin Time (aPTT): the measure of the clotting factors in the blood. The normal range is 30 to 45 seconds.

• Thrombin Time. Normal time is 12 to 14 seconds.

• Fibrinogen: This is also a protein that helps with clotting. The normal range is 200 to 400 mg/dl.

• D-Dimer: Increased levels indicate increased blood clot formation, suggestive of disorders such as deep vein thrombosis and embolisms.

Basic Metabolic Panel: These evaluate the various electrolyte levels in the body, and the various metabolic functions are assessed.

• Blood Sugar Levels: The tests are conducted to assess the glucose levels in the body, which is very important to diagnose and manage diabetes.

• Electrolytes: The levels of sodium, potassium, bicarbonate, chloride. These are crucial for maintaining balance and nerve function in the body.

Liver Function Tests: They help assess liver function. They include:

• Alanine transaminase.

• Aspartate transaminase.

• Alkaline phosphatase.

• Bilirubin.

When the results are abnormal, they suggest some form of damage to the liver, hepatitis, or other liver diseases.

Kidney Function Tests: These help assess kidney function and health. They include :

• Creatinine: Serum creatine is one of the waste products produced by the metabolism of muscles. Increased levels suggest some blockage for the kidneys to filter this waste. This could be suggestive of urinary tract obstruction or chronic kidney disease.

• Blood Urea Nitrogen: This is a waste product from the liver caused by protein breakdown. When there is an increased level, they are suggestive of impaired kidney function, congestive heart failure, and bleeding in the gastrointestinal tract.

• Urinalysis: This involves a detailed urine examination, and tests are conducted clinically and microscopically. If any proteins, blood cells, or glucose are present, they are all assessed and noted. Abnormalities indicate kidney dysfunction or urinary tract issues.

What Are the Uses of Blood Tests?

• Screening: Blood tests are done to help diagnose diseases at an early stage and initiate treatment sooner. This improves the prognosis of the disease to a great extent.

• Organ Function: Certain tests, such as liver and kidney function tests, are excellent evaluators of organ status. They help assess the levels and diagnose abnormalities or diseases.

• Nutritional Deficiencies: Blood tests are excellent indicators of any deficiencies in the body. Iron, calcium, and vitamin B12 can all be assessed with the help of blood tests.

• Assessing Infections: Infectious agents can be assessed with the help of certain markers in blood. Complete blood counts are excellent for evaluating initial infections.

Conclusion

To conclude, blood tests form an important part of the medical world by aiding in the assessment by providing generally hidden information, gaining insight into the patient's health status, and helping diagnose and manage. Interpreting these blood tests has to be done carefully, correlating it with age, gender, medical history, and clinical examination.