PMID- 11848463
OWN - NLM
STAT- MEDLINE
DCOM- 20020827
LR  - 20220410
IS  - 0340-6245 (Print)
IS  - 0340-6245 (Linking)
VI  - 87
IP  - 1
DP  - 2002 Jan
TI  - The APTT response of pregnant plasma to unfractionated heparin.
PG  - 92-7
AB  - Pregnancy is associated with a physiological increase in coagulation factors and 
      heparin binding proteins; both can affect the activated partial thromboplastin 
      time (APTT) in response to unfractionated heparin (UFH) invalidating the use of a 
      non-pregnant APTT therapeutic range. We compared the anticoagulant response of 
      UFH added in vitro to the plasma of 13 pregnant (third trimester) and 15 
      nonpregnant women to determine whether the measured APTT and antifactor Xa 
      activities are lower in pregnancy. Increasing concentrations of UFH were added to 
      platelet-poor plasma from each subject and the APTT and anti-factor Xa activity 
      were measured. The amount of UFH which was reversibly bound and neutralised by 
      plasma heparin binding proteins was assessed by comparing the anti-factor Xa 
      activity before and after addition of low affinity heparin (LAH). Fibrinogen, von 
      Willebrand factor antigen (vWF Ag) and factor VIII levels, were also measured. 
      The APTT response, assessed by the slope of the regression line of log APTT 
      versus added heparin concentration, was attenuated in pregnant plasma (0.76 
      s/U/mL versus 1.2 s/U/mL, p = 0.005) and was highly correlated to increased 
      non-specific plasma protein binding (47% versus 35% p <0.01) and increased 
      fibrinogen (5.1 g/L versus 2.8 g/L, p < 0.01) and factor VIII activity (2.7 U/mL 
      versus 1.2 U/mL, p <0.01). Thus, to achieve the same heparin level, pregnant 
      women require higher daily doses of UFH than non-pregnant women. However, if UFH 
      dose adjustments during the third trimester are based upon a non-pregnant APTT 
      therapeutic range, systematic overdosing of pregnant women will result, possibly 
      increasing the risk of bleeding and osteoporosis.
FAU - Chunilal, S D
AU  - Chunilal SD
AD  - Department of Medicine, McMaster University, Hamilton, Canada. 
      chunilal@bigpond.com
FAU - Young, E
AU  - Young E
FAU - Johnston, M A
AU  - Johnston MA
FAU - Robertson, C
AU  - Robertson C
FAU - Naguit, I
AU  - Naguit I
FAU - Stevens, P
AU  - Stevens P
FAU - Galashan, D
AU  - Galashan D
FAU - Oskamp, M L
AU  - Oskamp ML
FAU - Brennan, B
AU  - Brennan B
FAU - Ginsberg, J S
AU  - Ginsberg JS
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - Germany
TA  - Thromb Haemost
JT  - Thrombosis and haemostasis
JID - 7608063
RN  - 0 (Anticoagulants)
RN  - 0 (Antigens)
RN  - 0 (Factor Xa Inhibitors)
RN  - 0 (Von Willebrand antigen)
RN  - 0 (von Willebrand Factor)
RN  - 9001-27-8 (Factor VIII)
RN  - 9005-49-6 (Heparin)
SB  - IM
MH  - Adult
MH  - Anticoagulants/administration & dosage/*pharmacology
MH  - Antigens/blood
MH  - Blood Coagulation/*drug effects
MH  - Factor VIII/analysis
MH  - Factor Xa Inhibitors
MH  - Female
MH  - Heparin/administration & dosage/*pharmacology
MH  - Humans
MH  - *Partial Thromboplastin Time
MH  - Pregnancy
MH  - Pregnancy Trimester, Third/*blood
MH  - Reference Values
MH  - von Willebrand Factor/immunology
EDAT- 2002/02/19 10:00
MHDA- 2002/08/28 10:01
CRDT- 2002/02/19 10:00
PHST- 2002/02/19 10:00 [pubmed]
PHST- 2002/08/28 10:01 [medline]
PHST- 2002/02/19 10:00 [entrez]
PST - ppublish
SO  - Thromb Haemost. 2002 Jan;87(1):92-7.