Blood Tests

Blood Tests

What is a blood test?

Blood tests serve as a valuable diagnostic tool, delving into the composition of blood, which encompasses various cells, salts, and proteins.

Plasma, the liquid component of blood, solidifies outside the body, forming serum, devoid of clotting elements. Serum proves vital for chemical and immunological analyses, offering insights into immune responses against diseases.

Physicians can extract blood samples and culture infectious agents responsible for ailments, enabling precise identification under a microscope.

How is a blood test conducted?

Blood samples are obtained from either veins (carrying blood to the heart) or arteries (carrying blood away from the heart).

For minimal blood requirements, such as monitoring blood sugar in diabetes, a finger prick suffices.

Typically, blood tests are drawn from veins, often those near the elbow. A tourniquet enhances vein visibility, facilitating sample collection.

The site is sterilized, and a needle inserted into the vein, attached to either a vacuum blood collection tube or a syringe for low-pressure extraction. Once the required volume is obtained, the needle is withdrawn, and pressure applied with cotton wool before dressing the site.

Arterial blood collection, usually from the wrist, may cause slight discomfort due to increased nerve density in artery walls.

After arterial extraction, pressure is applied to prevent bleeding.

Needle sensitivity and blood aversion may lead to faintness; patients are advised to inform healthcare providers promptly.

What aspects of blood do doctors assess?

Blood comprises plasma and cells, primarily red blood cells (RBCs), white blood cells (WBCs), and platelets.

Red Blood Cells

Tests measure hemoglobin levels, essential for oxygen transport, and assess RBC size (MCV). Hematocrit gauges RBC volume, crucial for diagnosing anemia or severe bleeding.

Variations in RBC appearance may indicate specific anemias or infections.

White Blood Cells (WBCs)

Total WBC count and differential count assess immune response and identify potential infections or diseases like leukemia.

Platelets

These tiny cells aid clot formation. Low platelet counts increase bleeding risk, while high counts predispose to clotting disorders.

Blood Coagulation Examinations

Further tests evaluate blood clotting abnormalities, which can lead to excessive bleeding or clot formation. These assessments are crucial for patients on anticoagulant medications like warfarin, guiding dosage adjustments based on test results.