What is the basic definition of serum?

Serum is the liquid component of blood that remains after blood clots, meaning it lacks clotting factors like fibrinogen.

What is the basic definition of plasma?

Plasma is the liquid component of blood that remains after cells are removed, and it still contains all clotting factors.

What is the main difference between serum and plasma?

The main difference is clotting factors, as plasma contains fibrinogen and other clotting proteins while serum does not.

Which is better for blood typing tests, serum or plasma?

Plasma is generally better for blood typing because it contains clotting factors that help preserve red blood cell antigens for accurate testing.

Is serum more expensive to produce than plasma?

Yes, serum is more expensive to produce because it requires a clotting process and additional centrifugation steps to separate it.

What are the safety risks of using plasma for medical treatment?

Plasma carries a small risk of allergic reactions or transfusion-related infections, though screening has greatly reduced these dangers.

Which blood component is compatible with all patients for transfusion?

Plasma from type AB donors is universally compatible with all patients because it lacks anti-A and anti-B antibodies.

What is a common beginner mistake when separating serum from plasma?

A common mistake is using a tube without anticoagulant and then expecting plasma, which actually yields serum instead.

Can serum and plasma be used interchangeably in laboratory tests?

No, serum and plasma cannot be used interchangeably because their different compositions can alter results for many chemistry tests.

Can I switch from plasma donation to serum for my medical condition?

You cannot switch between plasma and serum for treatment because they serve different medical purposes, as plasma is for transfusion while serum is for lab testing.

Difference Between

Difference Between Serum and Plasma

Written byNex Virox Team

Editorial Team

Reviewed byVarshal Nirbhavane

Senior SEO & Organic Growth Professional · 5+ years

Published: August 28, 202617 min read

Quick answer

The main difference between Serum and Plasma is that serum lacks clotting factors, while plasma retains them. Serum is the liquid component left after blood clots, while Plasma is the liquid portion containing clotting factors and cells.

Key takeaways

Core distinction: Plasma contains clotting factors and fibrinogen; serum lacks them after blood clotting.
How each works: Plasma is liquid blood with cells; serum is plasma minus clotting proteins.
Cost and effort: Serum requires clotting time and centrifugation, while plasma needs anticoagulant tubes.
Best-fit use case: Plasma suits coagulation studies; serum suits chemistry tests requiring no clotting interference.
Most common mistake: Using serum for coagulation assays yields falsely low clotting factor measurements.

Table of Contents18 sections

Difference Between Serum and Plasma: Comparison Table

Aspect	Serum	Plasma
Definition	Fluid remaining after blood clots, with fibrinogen and clotting factors removed.	Fluid portion of blood kept liquid by anticoagulants, retaining all clotting factors.
Purpose	Used for serology, hormone assays, and antibody or antigen detection testing.	Preferred for coagulation studies, therapeutic transfusions, and coagulation factor assays.
Core Mechanism	Whole blood coagulates, activating the coagulation cascade until fibrinogen converts to fibrin.	Anticoagulant additives like EDTA or heparin bind calcium to prevent clotting entirely.
Composition	Contains proteins, electrolytes, hormones, and waste but lacks fibrinogen and clotting factors.	Contains all blood proteins, glucose, electrolytes, and clotting factors in suspension.
Clotting Factors	Absent because consumed during clot formation, including fibrinogen and prothrombin.	Present and fully functional, including fibrinogen, prothrombin, and factor VIII.
Fibrinogen	Converted into fibrin strands during clot formation, leaving serum without this protein.	Remains dissolved in plasma because anticoagulants prevent fibrin formation entirely.
Preparation Time	Requires waiting roughly 30 to 60 minutes for complete clot formation.	Separated promptly after centrifugation, typically within 30 minutes of collection.
Centrifugation	Centrifuged after clotting completes, typically at 1000 to 2000 times gravity.	Centrifuged immediately after collection to separate cells from liquid before clotting.
Collection Tube	Collected in plain red-top tubes without any anticoagulant additive present.	Collected in lavender or light-blue tubes containing EDTA, citrate, or heparin.
Yield Volume	Yields approximately 10 to 20 percent less volume than plasma from identical blood.	Yields a larger volume because fibrinogen and clotting factors remain in solution.
Storage Stability	Stable when frozen at minus 20 degrees Celsius for months without degradation.	Requires rapid freezing at minus 70 degrees Celsius to preserve labile factors.
Freeze-Thaw	Survives freeze-thaw cycles well because labile factors are already absent.	Loses labile factors like factor V and factor VIII with each freeze-thaw cycle.
Turnaround Time	Requires longer processing time due to mandatory waiting for clot formation.	Processed faster because no waiting period is required before centrifugation occurs.
Test Accuracy	Preferred for serology tests where fibrinogen interference could skew results.	Preferred for chemistry panels because anticoagulant contamination may affect certain assays.
Hemolysis Risk	Clotting process may release cellular contents that interfere with certain tests.	Rapid processing reduces hemolysis risk because cells are separated quickly.
Anticoagulant Use	Requires no anticoagulant, allowing the blood to naturally clot completely.	Requires chemical anticoagulants such as EDTA, citrate, or heparin to stay liquid.
Typical Tests	Used for immunology, serology, blood typing, and hormone level testing.	Used for coagulation panels, electrolyte tests, and therapeutic plasma exchange procedures.
Clinical Role	Diagnostic testing for infectious diseases like hepatitis and autoimmune conditions.	Therapeutic use in transfusion medicine, burn treatment, and clotting factor replacement.
Production Cost	Lower processing cost because no anticoagulant additives are required.	Higher cost due to specialized collection bags and anticoagulant additive expenses.
Processing Speed	Slower to prepare because clotting time adds unavoidable delay.	Faster to prepare because no waiting for coagulation to complete.
Protein Content	Lacks fibrinogen and clotting proteins consumed during the clotting process.	Contains all plasma proteins including albumin, globulins, and fibrinogen.
Interference	Free from anticoagulant interference, giving clean results for certain immunoassays.	Anticoagulants may interfere with potassium, calcium, or enzyme assays.
Factor Stability	Labile factors absent, so no risk of losing unstable clotting proteins.	Labile factors degrade quickly if not processed or frozen within hours.
Donation Source	Derived from whole blood donations processed in blood banks.	Derived from plasmapheresis, a dedicated plasma donation procedure.
Regulatory Use	Used for diagnostic products like vaccines and therapeutic immunoglobulins.	Used for therapeutic products like albumin and clotting factor concentrates.
Common Confusion	Often confused with plasma because both are straw-colored fluids.	Often confused with serum because both appear similar without visible red cells.
Limitation	Cannot be used for coagulation testing because clotting factors are absent.	Cannot be used for certain serology tests because anticoagulants interfere.
Best Scenario	Best for antibody detection, autoimmune disease screening, and serological testing.	Best for emergency transfusion, coagulation studies, and factor deficiency diagnosis.
Key Distinction	Defined by absence of fibrinogen and all clotting factors.	Defined by presence of fibrinogen and all clotting factors.
Best Fit	Best fit for clinical chemistry and immunology testing in laboratories.	Best fit for emergency medicine and therapeutic transfusion applications.

What Is Serum?

Serum is the liquid component of blood that remains after blood has clotted, with clotting factors removed. It is the clear, straw-colored fluid that carries antibodies, hormones, and electrolytes. Serum exists because it provides a stable sample for laboratory testing.

Definition of Serum
Serum is the clear, yellowish extracellular fluid obtained after whole blood undergoes coagulation, leaving fibrinogen, clotting factors, and cells removed. It contains proteins, electrolytes, and metabolic products. This acellular fluid is collected after centrifugation of clotted blood, distinct from plasma, which retains clotting proteins.

Key Characteristics of Serum

Characteristic	What It Means in Practice
No clotting factors	Fibrinogen and prothrombin are consumed during clotting, leaving serum deficient in these proteins.
Clear appearance	Typically yellow and transparent, though hemolysis or lipemia can visibly alter its normal clarity.
Requires clotting time	Whole blood must sit for 30-60 minutes to clot before centrifugation separates the liquid fraction.
Higher analyte concentration	Potassium and certain enzymes measure higher here compared to plasma because cells release contents during clotting.
Stable storage	Frozen serum retains analyte integrity for weeks, allowing batch testing across different days.
No anticoagulant needed	Collection tubes contain no additives, simplifying collection protocols in clinical settings.
Immunoglobulin presence	Antibodies remain fully intact and measurable, making it standard for serology and serology testing.
Non-cellular fluid	Red and white cells, plus platelets, are entirely absent after proper centrifugation removes them.
Specific gravity	Density ranges around 1.024, slightly heavier than water, affecting separation protocols.
Proteome composition	Contains albumin, globulins, and acute-phase proteins, useful for protein electrophoresis panels.

Common Examples of Serum

Blood serum – the standard laboratory specimen for metabolic panels, like glucose and creatinine tests.
Fetal bovine serum – a cell culture supplement providing growth factors for research cell lines.
Blood typing serum – used in crossmatching to detect antibodies against donor red cells.
Antivenom serum – a therapeutic preparation containing antibodies against snake venom toxins.
Convalescent serum – blood-derived fluid from recovered patients, historically used for passive immunity transfer.
Serum albumin – the most abundant protein fraction, often measured to assess nutritional status.
Serum protein electrophoresis – a diagnostic sample used to separate and identify monoclonal gammopathy patterns.
Serum osmolality – a test measuring particle concentration, used for hydration and electrolyte evaluation.
Serum bilirubin – a common chemistry test measuring bilirubin for liver and hemolysis assessment.
Serum separator tube – a collection device with gel that separates serum for chemistry analyzers.

Advantages and Limitations of Serum

Advantages	Limitations
Simpler collection requires no anticoagulant, reducing pre-analytical error from additive interference.	Clotting takes 30-60 minutes, delaying results compared to plasma's immediate availability.
Eliminates fibrinogen interference, preventing fibrin strands from clogging automated analyzers.	Clotting can induce hemolysis, falsely elevating potassium and LDH levels during processing.
Standard for serology, as complement activation during clotting removes interfering complement proteins.	Cell metabolism continues during clotting, causing measured glucose to decrease over time.
Provides a cleaner sample for protein electrophoresis without fibrinogen's background noise.	Some analytes, like potassium, measure artificially higher in serum due to platelet activation.
Allows testing on frozen samples for biobanking, with long-term stability at -20°C.	Activated platelets release intracellular contents, making certain enzyme measurements unreliable.
Widely compatible with most clinical chemistry analyzers and reference laboratory platforms.	Incomplete clotting in anticoagulated patients yields fibrin, causing gel barrier failure.
Reduces risk of clot formation in tubing, preventing line occlusion during infusion.	Requires a clot activator tube, adding a phlebotomy tube type and collection step.
Provides a physiological baseline, reflecting post-clotting state, not circulating blood composition.	Lower yield per volume, as clotting consumes fluid, yielding less serum than plasma.
Preferred for therapeutic drug monitoring, with fewer interfering proteins for immunoassays.	Not suitable for coagulation studies, which explicitly requires plasma to assess factor activity.
Enables retrospective analysis of stored samples, allowing retrospective testing on older specimens.	Cannot be used for transfusion, as cellular components are removed, unlike plasma products.

What Is Plasma?

Plasma is the liquid portion of blood that remains after cells are removed. It carries nutrients, hormones, and proteins throughout the body. Plasma also transports waste products to organs for removal, making blood circulation and clotting possible.

Definition of Plasma

Plasma is the liquid component of blood that suspends red blood cells, white blood cells, and platelets. It consists of roughly 92% water, plus dissolved proteins, electrolytes, and waste products. Plasma serves as the transport medium for cellular components and dissolved substances.

Key Characteristics of Plasma

Characteristic	What It Means in Practice
Straw-colored fluid	Plasma appears pale yellow because of dissolved bilirubin and other pigments in the liquid fraction.
Clotting factors present	Fibrinogen and other proteins remain active, enabling blood to clot when a vessel is damaged.
Water-based matrix	Water makes up roughly 92% of plasma volume, dissolving salts and proteins for transport.
Protein-rich composition	Albumin, globulins, and fibrinogen carry lipids, antibodies, and clotting agents through circulation.
Circulatory carrier	Plasma moves hormones, glucose, electrolytes, and cellular waste between organs and tissues.
Antibody transport	Immunoglobulins in plasma help neutralize pathogens and provide passive immunity when transfused.
Electrolyte balance	Sodium, potassium, and calcium in plasma maintain nerve function and muscle contraction.
Non-cellular suspension	Plasma holds red and white blood cells in suspension without being a cell itself.
Osmotic regulation	Albumin proteins in plasma maintain oncotic pressure, keeping fluid inside blood vessels.
Waste transport	Urea and creatinine travel in plasma to the kidneys for filtration and excretion from the body.

Common Examples of Plasma

Fresh frozen plasma – Donated plasma frozen within hours to preserve clotting factors for transfusion therapy.
Fresh frozen plasma – Standard therapeutic product used to replace multiple clotting factors after major trauma or liver failure.
Convalescent plasma – Plasma from recovered patients containing antibodies used for infectious disease treatment trials.
Source plasma – Plasma collected specifically for fractionation into albumin, immunoglobulins, and clotting factor concentrates.
Platelet-rich plasma – Concentrated plasma used in orthopedic injections to promote tissue healing in joints and tendons.
Albumin solution – Purified plasma protein used clinically to restore blood volume in burn patients or shock.
Plasma-derived factor VIII – Clotting factor concentrate extracted from pooled plasma to treat hemophilia A bleeding episodes.
Intravenous immunoglobulin – Plasma-derived antibody preparation used for immune deficiency and autoimmune conditions.
Plasma for fractionation – Industrial plasma supply processed into multiple therapeutic proteins for pharmaceutical manufacturing.
Liquid plasma – Whole blood plasma separated within hours and stored refrigerated for up to one day of clinical use.

Advantages and Limitations of Plasma

Advantages	Limitations
Plasma rapidly replaces multiple clotting factors at once, treating bleeding from liver disease or warfarin overdose.	Transfusion reactions can cause allergic responses, transfusion-related lung injury, or circulatory overload in recipients.
Plasma expands blood volume quickly, stabilizing patients with severe burns or major hemorrhagic shock.	Plasma carries infection risk despite screening, with slight residual risk for viral transmission from donors.
Plasma provides antibodies that confer passive immunity to patients with antibody deficiency syndromes.	Fresh frozen plasma requires frozen storage at -18°C, demanding specialized equipment and cold-chain logistics.
Plasma is fractionated into albumin, immunoglobulins, and factor concentrates for diverse clinical therapies.	Plasma has short shelf life after thawing, forcing use within hours or discard if not transfused promptly.
Plasma supports therapeutic apheresis procedures that remove pathological antibodies in autoimmune disease.	Plasma donation frequency limits donors to limited sessions per year, restricting supply for fractionation.
Plasma is readily available from blood banks with standard donor screening and testing protocols.	Plasma is costly to process, test, and store, making it expensive compared to crystalloid volume expanders.
Plasma contains natural anticoagulant proteins that regulate coagulation and fibrinolysis in circulation.	Plasma lacks cellular oxygen-carrying capacity, making it ineffective for treating anemia or hypoxia.
Plasma supports research into biomarkers, drug metabolism, and disease diagnostics with minimal processing.	Plasma is contraindicated in patients with known IgA deficiency, severe cardiac failure, or documented intolerance.
Plasma enables rapid assessment of electrolyte and protein abnormalities through laboratory testing.	Plasma degrades labile coagulation factors during storage, losing activity of factors V and VIII over time.
Plasma is used in manufacturing hyperimmune globulins for tetanus, rabies, and varicella prophylaxis.	Plasma donation requires strict donor eligibility, excluding many healthy individuals for travel or medication histories.

Similarities Between Serum and Plasma

Shared Aspect	How Serum and Plasma Are Alike
Blood Components	Both serum and plasma originate from whole blood and contain essential proteins and dissolved substances.
Fluid Fraction	Both serum and plasma represent the liquid portion of blood after cellular elements are removed.
Clinical Testing	Both serum and plasma are common samples used for diagnostic laboratory testing and clinical analysis.
Protein Presence	Both serum and plasma contain albumin, globulins, and other vital proteins in their liquid composition.
Electrolyte Content	Both serum and plasma carry sodium, potassium, chloride, and other electrolytes for bodily function.
Metabolic Waste	Both serum and plasma transport metabolic waste products like creatinine and urea for excretion.
Nutrient Transport	Both serum and plasma carry glucose, amino acids, and lipids to tissues needing these nutrients.
Hormone Carriage	Both serum and plasma transport hormones from endocrine glands to target organs throughout the body.
Medical Diagnostics	Both serum and plasma serve as critical specimens for diagnosing diseases and monitoring patient health.
Laboratory Processing	Both serum and plasma undergo centrifugation and processing steps within a clinical laboratory setting.
Sample Collection	Both serum and plasma require blood collection through venipuncture from a patient's vein.
Antibody Detection	Both serum and plasma contain antibodies used for detecting immune responses and infections.
Enzyme Measurement	Both serum and plasma contain enzymes measured for assessing organ damage and metabolic function.
Bilirubin Levels	Both serum and plasma carry bilirubin for evaluating liver function and jaundice evaluation.
Coagulation Factors	Both serum and plasma contain clotting factors, though serum has fewer after clot formation.
Storage Conditions	Both serum and plasma require refrigerated or frozen storage to preserve sample integrity.
Reference Ranges	Both serum and plasma use established reference ranges for interpreting laboratory test results.
Quality Control	Both serum and plasma require quality control measures to ensure accurate and reliable testing outcomes.
Research Applications	Both serum and plasma are widely used in biomedical research for studying disease biomarkers.
Biomarker Analysis	Both serum and plasma serve as sources for detecting biomarkers in medical diagnostics.
Infection Markers	Both serum and plasma carry markers indicating bacterial or viral infections for diagnosis.
Drug Monitoring	Both serum and plasma are used for therapeutic drug monitoring and toxicity assessment.
Centrifugation Use	Both serum and plasma are separated from blood cells using a centrifuge process.
Anticoagulant Impact	Both serum and plasma are affected by anticoagulants, which prevent blood from clotting.
Patient Monitoring	Both serum and plasma are used for monitoring chronic conditions like diabetes and kidney disease.
Nutritional Assessment	Both serum and plasma are used for assessing nutritional status and protein levels.
Immunology Testing	Both serum and plasma are used in immunology for detecting antibodies and antigens.
Hemolysis Sensitivity	Both serum and plasma are sensitive to hemolysis, which can alter test results.
Standard Protocols	Both serum and plasma are handled following standard protocols for collection and processing.
Long-term Storage	Both serum and plasma can be stored long-term for future testing and research.

Serum or Plasma: Which Should You Choose?

The single variable that decides the choice is whether you need clotting factors for your test or therapy. Plasma contains fibrinogen and other clotting proteins because it is collected with an anticoagulant. Serum lacks these proteins because the blood clotted naturally during collection. Choose based on what your assay measures.

When to Use Serum

Choose Serum when you need biochemical analysis without clotting factors interfering with results. Clinical chemistry tests, such as glucose, cholesterol, and liver panels, routinely use serum. It is also preferred when sample storage exceeds a few hours. Serum offers higher stability for many analytes, and it is cheaper to produce without special collection tubes.

When to Use Plasma

Choose Plasma when you need accurate coagulation studies or rapid turnaround for critical care results. Coagulation panels, such as PT and aPTT, require plasma because they measure clotting function directly. Plasma is also ideal for blood transfusions and factor replacement therapies. It prevents clotting during collection, preserving cellular components for immediate analysis.

Common Misconceptions About Serum and Plasma

Common Myth	The Reality
Serum and plasma are exactly the same fluid in the blood.	Serum is plasma without clotting factors, while plasma contains fibrinogen and clotting proteins, so they differ.
Plasma is the liquid left after blood clots.	Plasma is the liquid portion of uncoagulated blood, while serum forms only after blood clotting occurs.
Serum contains all the proteins found in blood.	Serum lacks fibrinogen and other clotting factors that plasma retains, so serum has fewer proteins.
Plasma and serum have identical chemical compositions.	Plasma contains clotting factors like fibrinogen, but serum lacks these factors after coagulation removes them.
You can separate serum from blood without any additives.	Serum requires a clot activator or centrifugation, while plasma needs an anticoagulant to prevent clotting.
Blood plasma is produced only inside bone marrow.	Plasma is the liquid component of blood, while bone marrow produces cells, not the plasma itself.
Serum is better for every type of blood test.	Plasma is preferred for tests needing clotting factors, while serum suits chemistry tests without anticoagulants.
Plasma is the same as the fluid in serum.	Plasma contains fibrinogen and clotting proteins, while serum is plasma without those clotting components.
Serum can be stored at room temperature indefinitely.	Serum degrades without proper refrigeration, while plasma requires freezing or specific storage conditions to remain stable.
Plasma is a waste product of blood processing.	Plasma is a valuable blood component used for therapies, while serum is a diagnostic sample after clotting.
Serum has the same volume as plasma in blood.	Plasma constitutes about 55% of blood volume, while serum is slightly less after clotting removes fibrinogen.
Plasma contains no cells or cellular components.	Plasma is cell-free fluid, but it carries proteins, while serum also lacks cells after centrifugation.
Serum is collected from living donors routinely.	Serum is derived from clotted blood samples, while plasma is collected from live donors via apheresis.
Plasma is only used for cosmetic procedures.	Plasma is critical for transfusions and therapies, while serum is used mainly for diagnostic laboratory testing.
Serum and plasma have identical clotting properties.	Plasma retains clotting ability with fibrinogen, while serum has no clotting factors and cannot clot.
Plasma is a type of blood cell.	Plasma is a liquid matrix, not a cell, while serum is also a fluid component derived from blood.
Serum is produced by the liver as a fluid.	Serum is not produced by an organ, while plasma is derived from blood, not synthesized separately.
Plasma is identical to serum in every test.	Plasma contains clotting proteins like fibrinogen, while serum lacks them, causing different test results.
Serum is always yellow or yellow-colored liquid.	Serum can appear clear or straw-colored, while plasma may appear similar but contains fibrinogen and clotting factors.
Plasma is the same as blood serum in labs.	Plasma requires anticoagulant tubes, while serum is collected in plain tubes without any anticoagulant added.
Serum has no use in medical treatments.	Serum is used in diagnostics and vaccines, while plasma is used therapeutically for clotting factor replacement.
Plasma is a solid component of blood.	Plasma is a liquid component, while serum is also liquid but distinct from cellular components like red cells.
Serum is collected without any centrifugation process.	Serum requires clotting and centrifugation, while plasma requires anticoagulant and centrifugation to separate cells.
Plasma is the same as interstitial fluid.	Plasma is blood's liquid fraction, while serum is derived from plasma but lacks clotting factors entirely.
Serum contains white blood cells always.	Serum lacks cells after clotting, while plasma is cell-free but contains proteins and other dissolved substances.
Plasma is a waste product from blood donation.	Plasma is a donated product for patients, while serum is a byproduct of laboratory blood testing.
Serum is identical to plasma in composition.	Serum differs from plasma by lacking fibrinogen, while plasma retains all clotting factors and proteins.
Plasma is only found in arteries.	Plasma circulates in all blood vessels, while serum is not found circulating in the body naturally.
Serum is the same as blood without cells.	Serum is plasma minus clotting factors, while plasma is blood's liquid portion with fibrinogen and proteins.
Plasma and serum are interchangeable in medicine.	Plasma is used for transfusions, while serum is used for tests, so they are not interchangeable.

Difference Between Serum and Plasma

Difference Between Serum and Plasma is that serum is plasma minus clotting factors, while plasma retains them. Choose serum for antibody testing and biochemistry requiring clot-free samples. Choose plasma for coagulation studies and rapid results needing anticoagulants like EDTA or heparin.

FAQs on Difference Between Serum and Plasma

What is the basic definition of serum?: Serum is the liquid component of blood that remains after blood clots, meaning it lacks clotting factors like fibrinogen.
What is the basic definition of plasma?: Plasma is the liquid component of blood that remains after cells are removed, and it still contains all clotting factors.
What is the main difference between serum and plasma?: The main difference is clotting factors, as plasma contains fibrinogen and other clotting proteins while serum does not.
Which is better for blood typing tests, serum or plasma?: Plasma is generally better for blood typing because it contains clotting factors that help preserve red blood cell antigens for accurate testing.
Is serum more expensive to produce than plasma?: Yes, serum is more expensive to produce because it requires a clotting process and additional centrifugation steps to separate it.
What are the safety risks of using plasma for medical treatment?: Plasma carries a small risk of allergic reactions or transfusion-related infections, though screening has greatly reduced these dangers.
Which blood component is compatible with all patients for transfusion?: Plasma from type AB donors is universally compatible with all patients because it lacks anti-A and anti-B antibodies.
What is a common beginner mistake when separating serum from plasma?: A common mistake is using a tube without anticoagulant and then expecting plasma, which actually yields serum instead.
Can serum and plasma be used interchangeably in laboratory tests?: No, serum and plasma cannot be used interchangeably because their different compositions can alter results for many chemistry tests.
Can I switch from plasma donation to serum for my medical condition?: You cannot switch between plasma and serum for treatment because they serve different medical purposes, as plasma is for transfusion while serum is for lab testing.