Platelet function to estimate the bleeding risk in autoimmune thrombocytopenia.
BACKGROUND
Knowledge of platelet function may assist in patient care in chronic autoimmune thrombocytopenia (cAITP).


METHODS
We evaluated the association of platelet function with haemorrhage in 41 patients, median age 41 years (range 14-82 years, 24 females) with chronic autoimmune thrombocytopenia (cAITP). Samples were investigated for platelet P-selectin, and adhesion and aggregate formation under high shear conditions. Data were compared to those from 28 healthy controls (median age 39 years, range 23-70 years, 17 females) and correlated with a bleeding score of 0 (no bleeding) to 3 (overt mucosal bleedings).


RESULTS
P-selectin levels were higher in patients than in controls (P < 0.0004). Compared to controls, the patients' samples responded to high shear with decreased adhesion to the polystyrene surface (P < 0.0001), but formed aggregates of normal size. P-selectin expression was neither correlated with platelet counts, nor platelet adhesion, nor the bleeding score. Only the size of formed aggregates correlated with P-selectin (P = 0.01). Platelet counts (odds ratio 0.5, 95% confidence interval 0.22-0.88; P = 0.04) and adhesion (odds ratio 0.45, 95% confidence interval 0.17-0.87; P = 0.04) were independently inversely correlated with bleeding symptoms.


CONCLUSIONS
Platelet adhesion correlates with bleeding symptoms, while the size of aggregates that are formed under high shear correlates with in vivo platelet activation. The determination of these parameters may assist in estimating an individual bleeding risk and thus a decision for treatment.
Panzer
S
S
Clinic for Blood Group Serology, Medical University of Vienna, Vienna, Austria. simon.panzer@meduniwien.ac.at
Rieger
M
M
Vormittag
R
R
Eichelberger
B
B
Dunkler
D
D
Pabinger
I
I
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001760:Bleeding Time; D001780:Blood Coagulation Tests / Q000379:methods*; D018849:Controlled Clinical Trials as Topic; D005260:Female; D006470:Hemorrhage / Q000276:immunology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010973:Platelet Adhesiveness / Q000276:immunology*; D010974:Platelet Aggregation / Q000276:immunology*; D010976:Platelet Count; D010979:Platelet Function Tests / Q000379:methods*; D016553:Purpura, Thrombocytopenic, Idiopathic / Q000276:immunology*; D012307:Risk Factors; D012720:Severity of Illness Index