PTR Reference Data

HLA match grades, DSA-MFI thresholds, and ABO mismatch effects for platelet refractoriness

Educational Reference Only. This reference data is for educational purposes. Clinical decisions should be made in consultation with transfusion medicine specialists.

Success rates show clear hierarchy: Grade A ≈ DSA-absent (86%) > B1U (72%) > B2UX (62%) > C (48%) > D (31%)

Grade	Description	Success Rate	Turnaround	Availability
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Cumulative DSA-MFI <10,000 predicts transfusion success; permits "permissive mismatch" transfusions

Major ABO mismatch reduces CCI by 3.70 × 10³/L (~35% reduction)

CCI Interpretation Thresholds

Timepoint	Adequate Response	Inadequate Response	Clinical Significance
1-Hour CCI	≥7,500	<7,500	Immediate recovery - alloimmune status
24-Hour CCI	≥4,500	<4,500	Platelet survival - non-immune factors

Pattern Interpretation

Poor 1hr + Poor 24hr

Suggests alloimmune cause

HLA/HPA antibodies likely
Consider HLA antibody testing
Use HLA-matched/crossmatch-compatible platelets

Good 1hr + Poor 24hr

Suggests non-immune cause

Infection, DIC, splenomegaly
Drug-induced consumption
Address underlying factors

Good 1hr + Good 24hr

Adequate response

No refractoriness
Continue standard platelets
Re-evaluate if pattern changes

Definition: Platelet refractoriness = 2+ consecutive inadequate responses after transfusion of ABO-compatible, fresh (<72 hours old) platelets.

Clinical Pearls

Optimizing Platelet Response

Use ABO-identical or ABO-compatible platelets
Use fresh platelets (<72 hours old when possible)
Address modifiable non-immune factors
Consider higher doses in larger patients

Common Non-Immune Factors

Fever/infection (consume platelets)
Splenomegaly (sequesters platelets)
DIC (consumptive coagulopathy)
Drugs: amphotericin B, vancomycin, heparin