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creation date: 2026-08-18 13:57
status: note
tags: Transition to Clerkship, Directed Independent Learning, Lectures

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Fluids and Transfusion

Module 1 – Indications for Blood Transfusion

Pre-Transfusion Compatibility Testing

Group and Screen

Before a transfusion occurs, group and screen must be performed.

Group: the recipient’s ABO (O, A, B, or AB) and RhD group (D+ or D-) (5 minutes)

• ABO is important as incompatibility can cause fatal, hemolytic transfusion reactions
• RhD antigen is immunogenic – RhD- recipient who is exposed to D+ blood (eg. pregnancy or transfusion) can develop anti-D hemolytic disease

Screen: the recipient’s plasma is screened for antibodies to clinically significant minor red blood cell antigens (45 minutes)

• 2% of patients have antibodies to minor RBC antigens (often due to exposure through pregnancy or transfusion)
• Positive screen can take hours to days to confirm antibody and then find antigen-negative RBC units available

Availability of RBC

Once a group and screen is complete, time is needed to obtain the RBC for the patient. This depends on:

• Previous and current test results: negative screen will have more blood availability
• Additional special transfusion needs (eg. sickle cell or irradiated blood)
• Clinical assessment of urgency of transfusion (eg. uncrossmatched blood is an option for emergencies)

Crossmatch

A crossmatch is the step to confirm a RBC unit is compatible for the patient.

For antibody screen negative:

• Immediate spin crossmatch mixes recipient plasma with compatible ABO (5 minutes)
• Electronic crossmatch by double checking recipient and donor ABO (2 minutes)

For antibody screen positive:

• RBC units with antigen negative selected
• Full antiglobulin crossmatch (at least 45 minutes)

In an emergency (where the minimum 45 minute delay can be detrimental), uncrossmatched blood can be issued.

• Group O RBCs if patient blood group has not been verified
• Group O, RhD negative RBCs for women of childbearing age
• Patient group-specific uncrossmatched RBCs if blood group is confirmed

Transfusion of Red Blood Cells

Basics

One unit of RBC:

• 300 mL
• Hematocrit of 65-70%
• Expected to raise hemoglobin by 10 g/L in average-sized non-bleeding adult
• Should be infused 1 unit at a time (in non-urgent situation)
• Kept refrigerated at a temp of 1-6ºC until patient is ready

Transfusion of RBCs:

• Should occur over 2 hours, 3.5 max
• Can be transfused over 3-3.5 hours if:
  • Patient age >70
  • History of heart failure
  • Left ventricular dysfunction
  • History of MI
  • Renal dysfunction
  • Positive fluid balance

Indications

Summarized as:

Hemoglobin	Recommendation
> 90 g/L	Not recommended except in unusual circumstances
70-90 g/L	Likely appropriate if evidence of impaired oxygen delivery
< 70 g/L	Likely appropriate
< 60 g/L	Highly recommended; may be tolerable if young and low risk of cardiovascular disease

Acute blood loss

• Group and screen should already have been performed if <80 g/L
• Maintain the hemoglobin >70 g/L during active bleeding
• Consider a higher hemoglobin target (> 80g/L) in patients with:
  • Unstable or acute coronary syndrome
  • Coronary artery disease
  • Uncontrolled/unpredictable bleeding
• Excessive practice (targeting >90 g/L) with GI bleed results in higher rate of re-bleeding and mortality

Anemia in the hospitalized patient

• If hemodynamically stable, consider transfusion if hemoglobin <70 g/L
• If patient undergoing orthopedic or cardiac surgery, or has pre-existing cardiovascular disease, consider transfusion if hemoglobin <80 g/L
  • These patients are unlikely to benefit if hemoglobin >100 g/L
• If a patient has presyncope, dyspnea, chest pain, or signs of cardiac ischemia, consider transfusion at higher hemoglobin levels (insufficient data for target)

Perioperative transfusion

• Perioperative transfusion is recommended if hemoglobin <70 g/L persistently in non-bleeding and asymptomatic patients
• Other management strategies include:
  • Blood conservation measures preoperatively (eg. erythropoietin, iron)
  • Careful surgical technique
  • Tranexamic acid and cell salvage during high blood loss surgery

Transfusion of Platelets

Basics

Platelets:

• Shelf-life of 7 days
• Stored at room temperature (20-24ºC)
• Adult dose contains 30x10^10 platelets in 300-350 mL
• One dose increases patient’s platelet count at 1 hour by 15-25x10^9 /L
• Should be infused over 1-2 hours (maximum 3.5 hours)

Options (2 kinds in Canada):

• Buffy coat derived platelets obtained from 4 whole blood donations and suspended in plasma from one of those donations
• Apheresis platelets (“single donor platelets”) derived from one donor and contains same amount of platelets as a buffy coat pool

Precautions:

• Prior to prescribing, must know the underlying cause of thrombocytopenia
• Risk of thrombosis (despite thrombocytopenia) with thrombotic thrombocytopenias
  • Heparin-induced thrombocytopenia (HIT)
  • Thrombotic thrombocytopenic purpura (TTP)
  • Catastrophic anti-phospholipid antibody
• Limited value of platelet transfusion with immune thrombocytopenias
  • Other modalities may be better: steroids, IV immunoglobulin, etc.
• For these two types, platelets are generally only used for treatment of serious bleeding

Indications

Non-immune thrombocytopenia
Results from the failure of platelet production within the bone marrow.

• Primary hematopoietic disease (eg. acute leukemia, myelodysplastic syndromes, aplastic anemia)
• Bone marrow replacement
• Drug effects (eg. chemotherapy)

Prophylactic platelet transfusion indicated if platelet ≤10x10^9 /L.

Surgical procedures
Procedures not associated with significant blood loss may require platelets if thrombocytopenic:

• Platelet count <20x10^9 /L
  • Transfuse 1 dose of platelets immediately prior to procedure
• Platelet count 20-50x10^9/L
  • Prepare 1 dose of platelets “on hold”
  • Transfuse if significant unexpected bleeding is present

Procedures associated with major blood loss or major surgery (anticipated blood los >500 mL):

• Transfuse platelet to keep platelet count >50x10^9/L
• If platelet count <50x10^9/L, transfuse 1 dose immediately prior to procedure

For patients to undergo neurosurgery, ophthalmologic procedures, or in patient with significant head trauma at risk of intracranial hemorrhage:

• Maintain platelets using transfusion to platelet count > 100x10^9/L
• Caution: risk of increased death/dependence at 3 months in patients receiving platelet transfusion vs. not

Platelet dysfunction
Marked microvascular (non-surgical) bleeding due to severe platelet dysfunction may require platelet transfusion regardless of platelet count. For example:

• Post-cardiopulmonary bypass
• Congenital platelet defects

Transfusion of Frozen Plasma

Basics

A unit of plasma:

• Average volume of 250 mL
• Obtained by apheresis from a single donor which may come in bags of 500 mL
• Stored as frozen plasma (FP) which require up to 30 minutes to thaw

Transfusion:

• ABO must be compatible
• Usual dose of plasma is 10-15 mL/kg (3-4 units)
• Each unit is given over 30 min - 2 hours depending on the urgency and risk of circulatory overload (maximum 3.5 hours per unit)
• Single dose expected to restore the prothrombin and partial thromboplastin times (INR and PTT) to 1.3–1.8x normal – confirm efficacy by rechecking INR/PTT
• Effect lasts 6 hours based on half-life of coagulation factors (factor VII has HL of 6 hours)

Indications

Plasma transfusion is indicated for:

• Active bleeding or prior to an operative procedure in patients with INR, PT, or PTT 1.8x normal or greater and no coagulation factor concentrates or other alternative therapies are available
• Massive rapid transfusion (at least 6-10 units of RBC expected to be transfused over first 6 hours) and clinical status requires immediate treatment prior to coagulation results
• Active bleeding or prior to an operative procedure in patients with severe liver disease with INR >2x normal

Note, FP is NOT useful for:

• INR <1.8
• Use of 1:1 FP:RBC replacement when patient is unlikely to require massive transfusion
• Coagulopathy in absence of bleeding or need for emergency surgery
• Elective reversal of warfarin where time allows for warfarin cessation and/or vitamin K
• Reversal of anticoagulants other than warfarin (plasma has no effect on reversing/neutralizing heparins or thrombin inhibitors)
• Volume expansion or “nutritional support”

Reversal of warfarin for patients who have significant bleeding or require urgent surgery:

• Vitamin K 5-10 mg IV (partial reversal within 2 hours and normalization within 6-24 hours)
• If emergency reversal required (<6 hrs): prothrombin complex concentrates and IV vitamin K
  • PCC contains factors II, VII, IX, X, protein C and S
  • Available as Octaplex and Beriplex
  • Dose of 1000/IU sufficient for a 50-90 kg patient with INR <3
  • Repeat INR 15 minutes after infusion
• Do not use PCC if INR <15, patient has coagulopathy unrelated to warfarin/vitamin K deficiency, history of heparin induced thrombocytopenia

Transfusion of Fibrinogen Replacement

Basics

Fibrinogen replacement is done with fibrinogen concentrate or cryoprecipitate.

Fibrinogen concentrate:

• Adult dose 4 grams equivalent to 10 units of cryoprecipitate
• Each dose raises fibrinogen concentration by 0.9 g/L
• Fibrinogen levels should be determined after infusion in determined

Cryoprecipitate:

• Unit has 10-15 mL volume
• Dose is 1 unit per 10kg body weight (although, typically dispensed as pool of 10 unit)
• Each dose raises fibrinogen concentration by 0.7 g/L
• Up to 30 minutes required to thaw and pool prior to transfusion
• Recommended infusion time is 15-30 minutes per dose (maximum 3.5 hours)
• Fibrinogen levels should be determined after infusion to determine efficacy

Indications

• For bleeding with fibrinogen <1 g/L
• For massive hemorrhage with fibrinogen <1.5–2.0 g/L
• For intracranial hemorrhage related to tPA with fibrinogen <2.0 g/L
• Clinical status suggestive of hypofibrinogenemia without time for laboratory confirmation
• Obstetrical hemorrhage: massive rapid hyperfibrinolysis can occur and may require prompt cyroprecipitate transfusion from outset of resuscitation
• Cyroprecipitate for heritoary disorder of hemostasis if specific factor concentrates are not available

Module 2 – Transfusion Reactions

Risk frequencies (approximate, wide confidence intervals) of events are summarized as follows:

Risk of Event	Event
1 in 13	Red cell sensitization, increasing risk of hemolytic transfusion reactions and hemolytic diseases of fetus and newborn
1 in 20	Febrile non-hemolytic transfusion reaction per pool of platelets
1 in 100	Transfusion-associated circulatory overload per transfusion episode
1 in 100	Minor allergic reactions (urticaria)
1 in 300	Febrile non-hemolytic transfusion reaction per unit of RBC (1 “donor exposure)
1 in 7,000	Delayed hemolytic transfusion reaction
1 in 10,000	Transfusion-related acute lung injury (TRALI)
1 in 10,000	Symptomatic bacterial sepsis per pool of platelets
1 in 40,000	ABO-incompatible transfusion per RBC transfusion episode
1 in 40,000	Serious allergic reaction per unit of component
1 in 100,000	Post-transfusion purpura
1 in 200,000	Death from bacterial sepsis per pool of platelets
1 in 250,000	Symptomatic bacterial sepsis per unit of RBC
1 in 500,000	Deatah from bacterial sepsis per unit of RBC
1 in 1,000,000	Transmission of West Nile Virus
1 in 4,000,000	Transmission of Chagas disease per unit of component
1 in 7,500,000	Transmission of hepatitis B virus per unit of component
1 in 7,600,000	Transmission of HTLV per unit of component
1 in 13,000,000	Transmission of hepatitis C virus per unit of component
1 in 21,000,000	Transmission of human immunodeficiency virus (HIV) per unit of component

Fever

Approach

Immediately:

1. Stop transfusion
2. Vitals
3. Re-check patient identification and name on blood product
4. Notify physician in charge and hospital blood bank

If any of the following:

• Temperature >39ºC
• Hypotension/shock
• Rigors
• Anxiety
• Dyspnea
• Back/chest pain
• Hemoglobinuria/oliguria
• Bleeding from IV sites
• Nausea, vomiting

Then, suspect hemolytic transfusion reaction or bacterial contamination:

• Collect blood samples to re-check ABO
• Clamp tubing and send unit back to blood bank for cultures and/or testing
• Send blood cultures from different IV site

If none, then administer acetaminophen 325 mg, continue transfusion cautiously.

Bacterial Sepsis

Background
Bacterial sepsis is the most common infectious hazard of transfusions (10% of transfusion associated fatalities) – most frequently with room temperature platelets.

Transfusion type	Bacterial contamination	Symptomatic septic reactions	Fatal bacterial sepsis
Buffy coat platelet pool	1 in 1,000	1 in 10,000	1 in 200,000
1 unit of RBC	1 in 50,000	1 in 250,000	1 in 500,000

Clinical manifestation

• Fever
• Rigors
• Tachycardia, hypotension, dyspnea
• Nausea, vomiting
• Disseminated intravascular coagulation

May also be asymptomatic if bacterial load is small. Organism may be detected in patient and remnant of transfused product – establishes diagnosis.

Management

• Stop transfusion
• Notify blood bank (who will inform supplier and thus quarantine and review same batch)
• Return residual blood components and tubing for culture
• Collect patient blood for culture
• Supportive therapy
• Prescribe empiric broad spectrum antibiotics (prior to blood cultures)

Acute Hemolytic Transfusion Reaction (AHTR)

Background
AHTR may occur due to:

• Incompatible transfused red cells (ABO/minor blood group)
  • ABO incompatibility occurs at rate 1 in 38,000
• Incompatible transfused plasma (high titers of anti-A/anti-B with group O platelets to non-group O recipient)

Clinical manifestation

• Fever
• Chills/rigors
• Hemoglobinuria
• Less commonly: nausea, vomiting, infusion site pain, flank pain, hypotension, renal failure, DIC

Management

• Stop transfusion
• Notify blood bank
• Check the identity of patient vs. bag label
• Return residual blood component and tubing for ABO re-check
• Send hemolysis workup: CBC, reticulocyte count, bilirubin, LDH, haptoglobin
• Provide supportive care: maintain urine output, manage DIC and hemorrhage

Febrile Non-Hemolytic Transfusion Reaction (FNHTR)

Background
FNHTR is a common transfusion reaction

• RBC: 1 in 300 units transfused
• Platelets: 1 in 20 pools of platelets transfused

May occur because:

• Factors (eg. cytokines) in the supernatant of the component transfused
• Recipient antibodies to WBCs or platelets in the component transfused

Clinical manifestation

• Fever (during or within 4 hrs of transfusion)
• May be associated with chills, rigors, nausea, vomiting, or hypotension

Management

• Acetaminophen 325-650 mg PO
• Meperidine 25-50 mg IV for severe rigors

In patients with significant and recurrent FNHTR, the following has been used (with limited evidence):

• Acetaminophen
• Corticosteroids
• Fresh components
• Plasma-depleted components
• Washed RBCs

Note, pre-medication with acetaminophen and diphenhydramine has not been shown to be effective in prevention.

Dyspnea

Transfusion Related Acute Lung Injury (TRALI)

Background
TRALI is a syndrome of acute respiratory distress with hypoxia and bilateral infiltrates on chest x-ray.

Additionally:

• Occurs within 6 hours of transfusion
• No evidence of CHF
• Incidence ~1 in 10,000 (unclear)
• Leading cause of transfusion-associated fatality (5-10% mortality)

Two possible mechanisms are:

• Passive transfer of HLA or granulocyte antibodies from donor to recipient
• Biologic response modifiers in transfused component

Both of which lead to cytokine release in the pulmonary circulation with capillary leak.

Clinical manifestation

• Dyspnea, hypoxia
• Onset within 1-2 hours of transfusion initiation (typically RBCs, platelets, and plasma); may be as long as 6 hrs
• Bilateral infiltrates on CXR
• Pulmonary capillary wedge pressure NOT elevated

Note that mild TRALI may present as transient hypoxia. Cases typically resolves in 24-72 hours

Management and prevention
Management:

• Stop transfusion immediately
• Supportive care
• Mechanical ventilation (75% of cases)
• Note, diuretics and steroids have not been shown to be beneficial

Prevention:

• Minimize inappropriate transfusion

Transfusion Associated Circulatory Overload (TACO)

Background
Results from circulatory overload due to:

• Impaired cardiac function
• Excessively rapid rate of transfusion

Occurs in 1 in 700 transfusions, but as high as 1 in 100 in perioperative or 1 in 17 in critically ill patients.

Clinical manifestation

• Dyspnea, orthopnea
• Elevated JVP
• Tachycardia, hypertension

Management and prevention
Management:

• Hold transfusion
• Administer oxygen and diuretics as needed
• Chest x-ray
• Restart the transfusion at a reduced rate (if clinical status permits)

Prevention:

• Pre-transfusion assessment for risk of fluid overload
• Avoid transfusing >1 unit at a time
• Transfuse over longer periods
• Pre-emptive diuretics before transfusion

Allergic Reactions

Anaphylaxis

Background
May present as dyspnea. Rare but severe and life threatening.

Etiology:

• Usually unexplained (80%)
• May involve:
  • Anti-IgA in IgA deficient patient
  • Antibodies to polymorphic donor proteins (eg. IgG, haptoglobin)
  • Transfusion of allergen to sensitized patient (eg. penicillin consumed by donor)
  • Passive transfer of IgE (eg. drugs, food)

Clinical manifestation

• Reaction begins within 1-45 min of starting transfusion
• Cutaneous reaction (urticaria, flushing) may be present (especially more severe reactions)
• Airway obstruction (dyspnea, chest pain, wheeze, stidor)
• Acute anxiety and feeling of impending doom
• Hypotension
• Nausea, vomiting

Management and prevention

• Stop transfusion (do not restart)
• Epinephrine, corticosteroids, diphenhydramine

Urticaria and Minor Allergic Reactions

Background
Minor allergic reactions occur in 1 in 100 plasma-containing components.

Clinical manifestation
May present as ≥1 urticarial lesion.

Additionally:

• Flushing, erythema, pruritus
• Cough, wheezing
• Nausea, vomiting
• Abdominal pain, diarrhea

Management and prevention

• Hold transfusion
• Diphenhydramine 25-50 mg PO or IV depending on severity
• Restart transfusion slowly if urticarial rash <2/3 of body surface and no associated symptoms of more severe allergic reaction
• For recurrent urticarial reaction, the following may be beneficial (limited evidence):
  • Pre-medication with diphenhydramine or cetirizine and/or corticosteroids
  • Plasma depletion of RBCs or platelets
  • Washed RBC or platelets

Hypotension

Background

• Associated with activation of bradykinin
• ACE inhibitors may contribute as ACE degrades bradykinin
• Most typically occurs with platelet transfusion
• Rarely associated with serious morbidity

Clinical manifestation

• Drop in SBP or DBP of 30 mmHg or more
• Nausea, vomiting, urticaria, dyspnea may be associated
• Usually lasts 1/2 to 3 hours

Management and prevention

• Should be detectable within 15 minutes (15 min vita check)
• Stop transfusion, do not restart
• Supportive care including IV fluids
• Consider TRALI and allergic reactions in ddx

Delayed Hemolytic Transfusion Reactions

Background

• Antibody-mediated destruction of transfused red cells 2 days or more after transfusion
• Antibody formation in recipient from exposure (eg. prior pregnancy or transfusion) but not detected during pre-transfusion screening
• Incidence is 1 in 7000

Clinical manifestation

• Onset 3 days to 2 weeks after transfusion
• New unexplained fever and jaundice
• Unexpected drop in post-transfusion hemoglobin level
• Evidence of hemolysis
  • Low hemoglobin
  • High bilirubin
  • High reticulocyte count
  • Spherocytosis
  • High LDH
  • Positive antibody screen
  • Positive direct antiglobulin test

Management and prevention

• Supportive care
• Previous transfusion/blood bank records should be routinely checked for past history of red cell antibody
• Notify patient and provide an antibody card for patient to carry in their wallet

Cytopenias After Transfusion

Transfusion Associated Graft vs Host Disease (TAGvHD)

Background

• Occurs when transfused immunocompetent cells mount an immune response to recipient’s tissues
• Can occur in immunocompromised recipients or immunocompetent individuals transfused a haploidentical product
• Rare but mortality >90%

Clinical manifestation

• Fever, rash, liver dysfunction, diarrhea 1-2 weeks post-transfusion followed by pancytopenia
• Diagnosis by biopsy of skin, liver, or bone marrow
• Overwhelming infections (cause of death)

Management and prevention
Management:

• Supportive care
• Antibiotics
• Treatment largely ineffective (immunosuppressive therapy and immediate allogeneic stem cell transplant may rarely work)

Prevention:

• Guidelines recommend irradiated components for specific patient groups (see online) including intrauterine transfusions, Hodgkin lymphoma, bone marrow/stem cell transplant, use of mabs

Post-Transfusion Purpura (PTP)

Background

• Transfusion of a platelet antigen positive component to a patient lacking the same antigen (most commonly HPA-1a positive product to negative patient)
• Autologous platelet destruction
• Diagnosis requires testing patient for platelet specific antibodies

Clinical manifestation

• Acute thrombocytopenia (platelet count <10x10^9/L in 80% of cases)
• Onset 1-24 days post-transfusion (average 9 days)

Management and prevention

• IVIG 1g/kg daily for 2 days
• Response expected by 4 days after treatment
• Platelets and RBC components compatible with antibody

Transfusion-Transmitted Infections

Infectious agents:

• HIV, hep C, human T-cell lymphotropic virus, hep B, Chagas, West Nile virus: see incidence rates above
• Rarer: viral (paravirus B19, hep A and E, Zika, Dengue, Chikungunya), protozoal (malaria, Trypanosoma cruzi, Toxoplasmosis, Leishmaniasis, Babesiosis), Helminthic (filariasis), spirochetal (Treponema pallidum, Borrelia burgdorferi), rickettsial (R. rickettsii, C. burnetti, Ehrlichia)

These infections have symptomatic effects – follow-up for treatment should be planned

Lecture - Introduction to Ordering Blood Products

Ordering:

• Amount & timing
• Special requests (irradiation)

Mandatory aspects:

• Guided by blood bank
• Reaction testing

Who to call:

• Blood bank (24/7 on call technologist)
• MRP

Do not submit transfusion order until:

• Patient consented (written)
  • What is blood transfusion
  • How is it administered
  • Products (blood)
  • Benefits (tx bleed, anemia, fatigue etc.)
  • Risks
    • Common: RBC antibodies (1/13), urticaria (1/100), TACO (1/100), fever (1/300 in rbc, 1/100 for plt)
    • Rare but worrisome: TRALI (1/10k), bacterial sepsis (increased risk of platelets due to differences in refridgeration)(1/250k), ABO incompatibility (1/350k), anaphylaxis (1/40k), viruses (1/1M)
  • Alternatives
  • Opportunity to ask questions
  • Right to refuse
  • Document conversation
• Indication correct
  • Hgb <60 definitely
  • Hgb <70 is often institutional cutoff
  • Hgb >70 requires more questions (just needs documentation)
  • Hgb >90 very rare
  • Hgb cutoffs may vary based on condition (eg. sickle cell may allow someone to tolerate a lower Hgb)
• Dose correct
• Timing correct

Ordering RBCs:

• Each unit has 300cc of concentrated RBC
• Raises Hgb by 10g/L in healthy adult; important because if not raising as expected, consider hemolysis or bleed
• One unit at a time in a 2 hr period, no more than 4hr max (except in emergency)

Special unit products:

• Irradiated blood: the product is put in the radiator prior to transfusion
• Phenotypic matched units: minimize the sensitization of RBC antigens
  • Especially relevant for people dependent on blood transfusion to live (eg. sickle cell, childbearing age women)

Group and screen:

• ABO group + RhD group
• Immediately reactive and highly immunogenic, respectively

Crossmatch:

• Confirms compatibility
• Spins donor red cells and recipient plasma and check for reaction

Cases:

1. D
2. D

Platelets:

• Indications
  • Normal is 150-400
  • Platelet <10 consider transfusion
  • Risk of spontaneous hemorrhage → majority occurs around 7, so 10 is cutoff used
• Contraindications
  • ITP - should deal with underlying, transfusion will not fix unless actively hemorrhaging
  • TTP - factor deficiency causing clotting which hyperconsumes platelets, worsens condition with transfusion (adds fuel to fire)
  • HUS - same as TTP
  • HIT - same as TTP
• Give 1 unit at a time, post-1hr CBC check
• Platelet refractoriness (anticipated platelet increased not seen)
  • Consumptive states
  • Hepatomegaly

Cases:

1. A, B

Plasma:

• Indications
  • TTP (supplements factor deficient)
• Plasma doesn’t correct to normal INR, slightly elevated
• Male plasma will not have anti-D (due to no exposure to fetus blood), AB blood plasma would not have anti-A or anti-B
  • Data show male plasma has less antibodies