Diagnostic utility of light transmission platelet aggregometry: results from a prospective study of individuals referred for bleeding disorder assessments.
BACKGROUND
Light transmission aggregometry (LTA) is commonly performed to assess individuals for bleeding disorders.


OBJECTIVE
The goal was to evaluate the incidence and spectrum of platelet function abnormalities in a prospective cohort of individuals referred for bleeding disorder assessments after exclusion of thrombocytopenia and von Willebrand disease.


METHODS
Subjects were healthy controls and patients from a prospective cohort of individuals referred for bleeding disorder assessments after exclusion of thrombocytopenia and von Willebrand disease. LTA was performed by standardized methods using platelet-rich plasma adjusted to 250x10(9) platelets L(-1). Maximal aggregation data were analyzed to determine the likelihood of detecting a platelet function disorder by LTA, and the sensitivity and specificity of LTA for platelet disorders.


RESULTS
The incidence of false positive LTA among subjects excluded of having bleeding disorders was similar to healthy controls. Abnormal LTA was more common in subjects with bleeding disorders and the likelihood of a bleeding disorder was significantly increased (odds ratio 32) when maximal aggregation was reduced with two or more agonists. Receiver operator curve analyses indicated that LTA had high specificity and moderate sensitivity for detecting inherited defects in platelet function and that the LTA agonists 1.25 microg mL(-1) collagen, 6 microM epinephrine, 1.6 mM arachidonic acid and 1.0 microM thromboxane analogue U44619 detected most inherited disorders with abnormal LTA.


CONCLUSIONS
LTA is valuable for detecting platelet function abnormalities among individuals referred for bleeding problems, particularly when the test indicates abnormal responses to multiple agonists.
Hayward
C P M
CP
Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada. haywrdc@mcmaster.ca
Pai
M
M
Liu
Y
Y
Moffat
K A
KA
Seecharan
J
J
Webert
K E
KE
Cook
R J
RJ
Heddle
N M
NM
D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000494:pharmacology; D016718:Arachidonic Acid / Q000494:pharmacology; D001791:Blood Platelet Disorders / Q000175:diagnosis*; D016022:Case-Control Studies; D003094:Collagen / Q000494:pharmacology; D004837:Epinephrine / Q000494:pharmacology; D005189:False Positive Reactions; D006801:Humans; D009391:Nephelometry and Turbidimetry; D010974:Platelet Aggregation / Q000187:drug effects; D010979:Platelet Function Tests / Q000379:methods* / Q000592:standards*; D011446:Prospective Studies; D012372:ROC Curve; D012680:Sensitivity and Specificity
D016718:Arachidonic Acid; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D003094:Collagen; D004837:Epinephrine