What is the expected increase in platelet count in an average adult patient after transfusion of one Single Donor Platelet Concentrate (SDPC)?

Expected Platelet Increment from One SDPC

One Single Donor Platelet Concentrate (SDPC/apheresis unit) should raise the platelet count by approximately 30,000-50,000/μL in an average-sized adult, or roughly 10,000/μL per 10¹¹ platelets transfused. 1

Standard Expected Increments

For apheresis (single donor) platelets:

• One SDPC contains approximately 3-6 × 10¹¹ platelets (equivalent to 4-8 whole blood-derived units) 1
• Expected increment: 30,000-50,000/μL in a 70 kg adult 1
• This translates to approximately 10,000/μL per apheresis unit 1

For whole blood-derived platelet concentrates (for comparison):

• One unit contains approximately 0.7-0.75 × 10¹¹ platelets 1
• Expected increment: 5,000-10,000/μL per unit 1
• For average-sized adults, a rough estimate is 2,000/μL per unit 2, 1

Calculating Adequacy of Response

The Corrected Count Increment (CCI) provides the most accurate assessment: 2, 1

• CCI Formula: (absolute increment × body surface area in m²) / (number of platelets transfused × 10¹¹) 2, 1
• A CCI ≥ 5,000 defines a satisfactory response 2, 1
• Measure platelet count 10-60 minutes post-transfusion for accurate assessment 3

Example calculation: If transfusion of 4 × 10¹¹ platelets produces an increment of 40,000/μL in a 2 m² recipient, the CCI = 40,000 × 2 / 4 = 20,000 (excellent response) 2

Clinical Factors That Reduce Expected Increments

Several conditions significantly diminish the expected platelet rise: 1

• Sepsis and active infection - can dramatically reduce increments 1
• Splenomegaly - approximately 33% of transfused platelets pool in the spleen normally 1
• Disseminated intravascular coagulation (DIC) and massive hemorrhage 1
• Alloimmunization - HLA antibodies present in approximately 90% of refractory cases 2, 1
• ABO incompatibility - can compromise post-transfusion increments 2, 1

In special populations:

• Trauma with massive transfusion: may only increase count by 5-10 × 10⁹/L 1
• Cirrhosis patients: produce only a small increase 1

Defining Platelet Refractoriness

Do not diagnose refractoriness based on a single poor response. 2, 1

Refractoriness requires: 2, 1

• At least two consecutive ABO-compatible transfusions (stored <72 hours)
• Both resulting in CCI <5,000 or absolute increment <2,000/unit
• Only then should investigation for alloimmunization or other causes be initiated 2

Critical Pitfalls to Avoid

• Never assume adequate increment without laboratory confirmation - always check post-transfusion counts, especially before invasive procedures 3
• Do not diagnose refractoriness after a single poor increment - patients may have poor response to one transfusion yet excellent increments with subsequent transfusions 2, 1
• Ensure ABO compatibility - ABO-incompatible platelets (e.g., A platelets to group O recipients) can compromise increments 2, 1
• Consider clinical context - fever, infection, and splenomegaly are common non-immune causes of poor increments that don't represent true refractoriness 1