[Effects of extracellular calcium concentration on platelets aggregation, coagulation indices and thromboelastography].
OBJECTIVE
To detect the effect of extracellular Ca2+ concentrations on test results of coagulation-related parameters.


METHODS
Blood samples of outpatient medical volunteers were collected and then different doses of calcium chloride added. The rate of platelet aggregation (n = 42), prothrombin time (PT), thrombin time (TT) and activated partial thromboplastin time (APTT) (n = 21) and parameters of thromboelastography (n = 30) were detected according to the standard protocols by plasma turbidimetry, coagulation and recalcification respectively.


RESULTS
When the plasma Ca2+ concentration was in the range of 0.1 - 33.7 mmol/L, the rate of platelet aggregation gradually increased with a increasing concentration of Ca2+. And the rates induced by adenosine diphosphate (ADP) and arachidonic acid (AA) were (51.8 +/- 9.6)% - (94.7 +/- 4.8)% and (64.4 +/- 12.2)% - (93.2 +/- 5.5)% respectively. When the Ca2+ concentration was 39.0 mmol/L, the rate decreased markedly [ADP (9.1 +/- 5.3)%, AA (11.1 +/- 4.5)%, both P < 0.01]. When the Ca2+ concentration was in the range of 0.1 - 33.7 mmol/L, the values of PT gradually increased with a increasing concentration of Ca2+. The values of TT changed in "V"-type and became minimum when the calcium concentration was 4.4 mmol/L. The values of APTT decreased with higher calcium concentrations and could not be determined when the concentration increased above 0.5 mmol/L. When the Ca2+ concentration was in the range of 0.4 - 27.3 mmol/L, the values of reaction time and coagulation time of thromboelastography changed in "V"-type and became nearly minimal at the Ca2+ concentration of about 2.1 mmol/L. The values of alpha angle and maximum amplitude changed in "V"-type and became maximal at the Ca2+ concentration of 2.1 mmol/L.


CONCLUSIONS
The effect of Ca2+ concentration on the testing results of coagulation-related parameters is significant. A high calcium ( > or = 39 mmol/L) can inhibit the platelet aggregation, coagulation factor activity and blood coagulation. The Ca2+ concentration of 2.1 mmol/L seems to be the optimal concentration for thromboelastography by recalcification method.
Department of Clinical Laboratory, Chinese PLA General Hospital, Beijing 100853, China.
Zu-Lan
ZL
Li
Xing-Ming
XM
Chen
Liang-Cheng
LC
Yang
Xin-Li
XL
Deng
Shu-Hong
SH
Fu
Li-Li
LL
Cai
Yu
Y
Zhou
Jing
J
Chen
Jie
J
Bai
Yu-Long
YL
Cong
D000368:Aged; D001777:Blood Coagulation; D002118:Calcium / Q000097:blood*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010314:Partial Thromboplastin Time; D010974:Platelet Aggregation; D011517:Prothrombin Time; D013916:Thrombelastography; D013918:Thrombin Time
D002118:Calcium