Normalization And Clinical Application Of Common Tests Used For Monitoring Heparin Therapy

Background and Objective:Heparin,including unfractionated heparin(UFH)and low molecular weight heparin(LMWH),as common anticoagulant drug is used to prevent venous thrombosis.In order to ensure the medication safety,the patients using unfractionated heparin(UFH)need to have the activated partial thromboplastin time(APTT)been monitored,while the ones using low molecular weight heparin(LMWH)don't have to.For certain patients(e.g.gerontal,obese,renal insufficiency patients)monitoring the anti Xa activity is necessary.In addition,heparin need antithrombin(AT)activity to exert the function of anticoagulation.Therefore,the AT activity should be monitored,too.Due to the situation that the anti-Xa activity was not carried out in most domestic laboratories and the performance verification of APTT and AT activity which carried out more were not normalization with less pre-analysis influence factors and clinical application research.This study was to discuss the pre-analysis influence factors of LMWH anti-Xa activity and the clinical application of gerontal patients anticoagulation treatment monitoring after a orthopedic surgery based on the performance verification of common items of heparin anticoagulation monitoring(including APTT,LMWH anti-Xa activity and AT activity),which provides evidence for the standardization of heparin anticoagulation treatment monitoring in clinical laboratories.The study also aims to learn that whether the LMWH anti-Xa activity level of patients achieve the therapeutic range,which could provide evidence for clinicians.Methods:1.The performance verification of common monitoring tests in the anticoagulant therapy using Heparin:According to CLSI H57-A,H26-A2,EP17-A,industry standard(WS/T 406-2012,WS/T 408-2012)and manufacture's requirements,LMWH anti-Xa activity,AT activity,and APTT were verified.(1)After calibrating the LMWH anti-Xa activity,the within-run precision,between-run precision,linear range,accuracy,limit of detection and carry-over rate were verificated.(2)After calibrating the AT activity,the within-run precision,between-run precision,linear range,accuracy was verified.(3)The within-run precision,between-run precision,and comparability of APTT were verificated.2.The pre-analysis influence factors of LMWH anti-Xa activity:According to researches at home and abroad,and manufacture's requirements,the condition of centrifugation which influencing testing results was discussed.(1)20 samples from patients using LMWH were collected to test anti-Xa activity after centrifuging once and twice respectively.(2)20 samples from patients using LMWH collected were divided into 5 groups.After placing at room temperature within 1 hour,2 hours,4 hours,8 hours and 24 hours,the samples were centrifuged and tested respectively.Then the effect on LMWH anti-Xa activity results of store time before centrifuging was discussed.(3)20 samples from patients using LMWH were selected,and their anti-Xa activity results centrifuged within 1 hour were compared with that of centrifuged at 4 hours,8 hours and 24 hours in room temperature and refrigeration condition respectively.Then the effect on testing results of store time at room temperature and refrigeration condition after centrifuging was discussed.3.The clinical application of LMWH anticoagulation treatment monitoring:40 gerontal patients using LMWH to prevent venous thrombosis after orthopedic surgery were selected to monitor LMWH anti-Xa activity.(1)The proportion of the anti-Xa activity in the therapeutic range of prophylaxis(0.20-0.50 anti-Xa IU/ml),lower than the prescribed minimum(<0.20anti-Xa IU/ml)and higher than the prescribed maximum(>0.50 anti-Xa IU/ml)were observed.(2)The correlation between anti-Xa activity of patients and sex,age,weight,body mass index,LMWH dosage,surgical type,hemoglobin,platelet count,creatinine clearance,PT,APTT,fibrinogen,D-dimer,AT activity,LMWH type and dose,underlying diseases were discussed.(3)The correlation between whether the patient had thrombosis and bleeding or not of patients and sex,age,weight,body mass index,the type and dosage of LMWH,surgical type,hemoglobin,platelet count,creatinine clearance,PT,APTT,fibrinogen,D-dimer,AT activity,LMWH type and dose,underlying diseases were discussed.Results:1.The performance verification of common monitoring tests in the anticoagulant therapy using Heparin:(1)For the LMWH anti-?a activity,the within-run precision and between-run precision were all lower than 0.10 anti-?a IU/ml.The linear range was 0-1.83 anti-?a IU/ml.The accuracy of the testing results were in accordance with the requirements of WS/T 406-2012.The LOD was 0.05anti-?a IU/ml,which meets the claims of manufactures and EP17-A2.The carryover rate was very low.close to 0.(2)For AT activity,the within-run precision and between-run precision were lower than 5.0%and 6.0%,respectively.The linear range was 0%-139%.The accuracy of the testing results were in accordance with the requirements of WS/T 406-2012.(3)For APTT,the within-run precision and between-run precision were lower than 1.0%and 5.0%,respectively,which could meet the requirements of manufactures.The comparability of APTT could meet industrial standard requirements.2.The pre-analysis influence factors of LMWH anti-Xa activity:(1)There were no statistically significant differences in the LMWH anti-Xa activity results between once and twice centrifugation.For the 20 samples,all the deviations were within ±0.03 anti-?a IU/ml.(2)There were no statistically significant differences in the LMWH anti-Xa activity results of 20 samples placed for less than 1 hour,2 hours,4 hours.8 hours,24 hours before centrifuging.For the 20 samples,all the deviations were within ±0.06 anti-Xa IU/ml.?There were no statistically significant differences in the LMWH anti-Xa activity results of 20 samples tested immediately and placed for 4 hours,8 hours and 24 hours at the room temperature and under refrigeration conditions,the deviations of all results were within ±0.06 anti-X a IU/ml.3.The clinical application of LMWH anticoagulation treatment monitoring:(1)Among the 40 patients investigated,the LMWH anti-Xa activity level of 25(62.5%)patients were among the range of treatment,while the anti-?a level of 5(12.5%)patients were lower than the prescribed minimum and 10(25.0%)patients were higher than the prescribed maximum.(2)There was correlation between the LMWH anti-?a activity and the type and dosage of LMWH as well as diabetes(p<0.05).The greater the dosage of LMWH,the higher the level of anti-Xa was observed.The patients who used LMWH Sodium Gel were more likely to have low anti-Xa activity,and the ones who used Enoxaparin Sodium were apt to have high anti-Xa activity.The patients with diabetes were more likely to have high anti-Xa activity.However,no statistically significant correlation was observed between the LMWH anti-?a activity and sex,age,weight,body mass index,surgical type,hemoglobin,platelet count,creatinine clearance,PT,APTT,fibrinogen,D-dimer,AT activity,other underlying diseases.(3)There was correlation between thrombus status and APTT,but it is not been seen in bleeding patients.The patients with shorter APTT were apt to be in thrombus status.However,no statistically significant correlation was observed between whether the patient had thrombosis and bleeding or not of patients and sex,age,weight,body mass index,surgical type,hemoglobin,platelet count,creatinine clearance,PT,APTT,fibrinogen,D-dimer,AT activity,the type and dosage of LMWH,other underlying diseases were discussed.Conclusion:1.The methods and results of performance verification in LMWH anti-?a,AT activity and APTT tests could meet the requirements of manufacturers and health industry standards,which could offer the references for clinical laboratories carrying out relevant studies.2.For the patients using LMWH,there were no statistically significant differences in the anti-?a activity results between centrifugal numbers,storage time and temperature,thus could provide the evidence for the pre-treatment analysis procedure for sample preparation.3.For the 40 patients,the LMWH anti-?a activity results were not within the expected treatment range for 37.5 percent patients,which should arouse clinicians,attention.There was correlation between the LMWH anti-?a activity and the type and dosage of LMWH as well as diabetes(p<0.05).The greater the dosage of LMWH,the higher the level of anti-?a was observed.The patients who used LMWH Sodium Gel were more likely to have low anti-?a activity,and the ones who used Enoxaparin Sodium were apt to have high anti-?a activity.The patients with diabetes were more likely to have high anti-?a activity.There was correlation between thrombus status and APTT.The patients with shorter APTT were apt to be in thrombus status.While the number of patients and monitoring time in the current study is limited,further researches with more samples and monitoring time are needed to investigate the relevant factors.