Interaction Between Platelet and Fibrinogen on Clot Strength in Healthy Patients.

OBJECTIVE: The purpose of this study was to explore the relationship between platelet concentration (PLT) (× 109 /L) and clot strength measured by thromboelastography maximum amplitude (TEG-MA) in healthy volunteers without a history of coagulation abnormalities. Secondarily, the relationship between fibrinogen (mg/dL) and TEG-MA was analyzed.

DESIGN: A prospective study.

SETTING: At a university's tertiary-care center.

MEASUREMENTS AND MAIN RESULTS: Using whole blood, PLT was reduced in the first part, and hematocrit was reduced in the second part of the study by hemodilution with platelet-rich and -poor plasma. Thromboelastography (TEG 5000 Haemonetics) was performed to measure clot formation and strength. Spearman correlation coefficients regression analyses and receiver-operating characteristics (ROC) were obtained to analyze the relationships among PLT, fibrinogen, and TEG-MA. Strong correlations were found in univariate analysis between PLT and TEG-MA (r = 0.88; p < 0.0001) and between Fibrinogen and TEG-MA (r = 0.70; p = 0.003). A biphasic relationship between PLT and TEG-MA was linear below a PLT 90 × 109 /L, followed by a plateau above 100 × 109 /L (p = 0.001). A linear relationship between fibrinogen (190-474 mg/dL) and TEG-MA (53-76 mm) was found (p = 0.0007). The ROC analysis found that PLT = 60 × 109 /L was associated with a TEG-MA of 53.0 mm. The product of PLT and fibrinogen concentrations was more strongly correlated (r = 0.91) to TEG-MA than either PLT (r = 0.86) or fibrinogen (r = 0.71) alone. A ROC analysis revealed that a TEG-MA of 55 mm was associated with a PLT × fibrinogen of 16,720.

CONCLUSION: In healthy patients, a PLT of 60 × 109 /L was associated with normal clot strength (TEG-MA ≥53 mm), and there was little change in clot strength with PLT >90 × 109 /L. Although prior analyses described the contributions of platelets and fibrinogen toward clot strength, they are presented and discussed independently. The data above described clot strength as an interaction among them. Future analyses and clinical care should evaluate and recognize the interplay.