A plasma sample is a specific part of your blood used in medical and scientific analysis. It represents the liquid portion of your blood after the cellular components have been removed. These samples are valuable for diagnosing various health conditions, monitoring disease progression, and assessing treatment effectiveness.
What Plasma Is
Plasma is the clear, yellowish liquid that constitutes approximately 55% of your total blood volume. It is primarily composed of water, accounting for about 90-92% of its content. The remaining 8-10% consists of various dissolved substances, including proteins, salts, hormones, nutrients, and waste products.
Among the proteins found in plasma are albumin, globulins, and fibrinogen. Albumin helps maintain fluid balance, while globulins play a role in the immune system, and fibrinogen is involved in blood clotting. Plasma also transports essential substances like sugars, amino acids, lipids, vitamins, and minerals throughout the body. It carries waste products from cells to organs responsible for their removal.
How Plasma is Obtained
Obtaining a plasma sample begins with a standard blood draw, known as venipuncture, from a vein. The blood is collected into a specialized tube containing an anticoagulant. This anticoagulant prevents the blood from clotting, allowing the plasma to remain in its liquid form.
Following collection, the blood-filled tube undergoes a process called centrifugation. This involves spinning the tube at high speeds in a machine called a centrifuge. The centrifugal force separates the blood components based on their density. The heavier cellular components, such as red blood cells, white blood cells, and platelets, settle at the bottom of the tube, forming a solid layer. The lighter, straw-colored plasma remains as the top liquid layer, which can then be extracted for testing.
Why Plasma is Used for Testing
Plasma is widely used for diagnostic testing because it offers a rich source of biomarkers, which are measurable indicators of biological processes, disease, or responses to treatment. These biomarkers can include proteins, hormones, enzymes, electrolytes, glucose, and lipids. Analyzing these substances in plasma provides detailed information about a patient’s health, aiding in the diagnosis of various conditions and the assessment of organ function.
The absence of cellular components in plasma prevents interference with certain laboratory tests. This stability allows for more accurate and reliable measurements of dissolved substances. Plasma testing is valuable for monitoring chronic diseases, such as diabetes through glucose levels, and evaluating the effectiveness of ongoing treatments. It also helps identify underlying health issues and guide personalized treatment plans.
Common Plasma Tests
Many routine medical tests utilize plasma samples to assess different aspects of health, including:
- Glucose tests, which measure blood sugar levels to diagnose and manage diabetes.
- Lipid panels, which include measurements of cholesterol and triglycerides to assess cardiovascular risk.
- Electrolyte panels, checking levels of sodium, potassium, and chloride, to help evaluate fluid balance and kidney function.
- Liver and kidney function tests, which measure specific enzymes and waste products, to provide insights into organ health.
- Coagulation tests, such as prothrombin time (PT/INR), conducted to assess blood clotting ability, particularly for individuals on anticoagulant medications.
- Hormone level tests, frequently performed for various hormones, such as thyroid hormones.