PMID- 34140837
OWN - NLM
STAT- MEDLINE
DCOM- 20210819
LR  - 20210819
IS  - 1846-7482 (Electronic)
IS  - 1330-0962 (Print)
IS  - 1330-0962 (Linking)
VI  - 31
IP  - 2
DP  - 2021 Jun 15
TI  - The missing slope: paradoxical shortening of activated partial thromboplastin 
      time in a patient on unfractionated heparin therapy.
PG  - 021003
LID - 10.11613/BM.2021.021003 [doi]
LID - 021003
AB  - This case report describes false shortening of activated partial thromboplastin 
      time (aPTT) due to erroneous optical reading of the clotting point in the 
      presence of unfractionated heparin (UFH), and a biphasic waveform. Activated 
      partial thromboplastin time performed on a coagulometer with photo-optical 
      detection yielded an ambiguous clotting curve characterized by an early and 
      steady decrease in light transmittance throughout the whole measuring range, with 
      the clotting point read at 65 seconds. Further investigations included 
      measurement of aPTT by means of a mechanical clot detection method as well as 
      determination of another heparin-sensitive coagulation assay, that is thrombin 
      time (TT), both being unmeasurably prolonged (> 150 seconds). Communication with 
      clinicians revealed that the patient was on continuous UFH therapy and had an 
      underlying sepsis, with highly elevated C-reactive protein (289 mg/L). The aPTT 
      measurements requested at three timepoints later during the same day revealed 
      gradual aPTT shortening and unveiled a peculiar biphasic waveform pattern. In 
      this case, unmeasurably prolonged aPTT due to UFH therapy was masked by a 
      biphasic aPTT curve pattern making only the first slope of the biphasic waveform 
      visible within the measuring range. The early decrease in plasma light 
      transmittance mimicked optical changes related to clot formation, thus causing 
      erroneous optical reading and yielding a falsely shortened aPTT. This case 
      emphasizes that such a pattern should be carefully inspected, especially when a 
      combination of a critically ill condition and UFH therapy is present, in order to 
      prevent erroneous reporting of aPTT and potential adverse effects on patient 
      care.
CI  - Croatian Society of Medical Biochemistry and Laboratory Medicine.
FAU - Lapic, Ivana
AU  - Lapic I
AD  - Department of Laboratory Diagnostics, University Hospital Centre Zagreb, Zagreb, 
      Croatia.
FAU - Loncar Vrancic, Ana
AU  - Loncar Vrancic A
AD  - Department of Laboratory Diagnostics, University Hospital Centre Zagreb, Zagreb, 
      Croatia.
FAU - Coen Herak, Desiree
AU  - Coen Herak D
AD  - Department of Laboratory Diagnostics, University Hospital Centre Zagreb, Zagreb, 
      Croatia.
FAU - Rogic, Dunja
AU  - Rogic D
AD  - Department of Laboratory Diagnostics, University Hospital Centre Zagreb, Zagreb, 
      Croatia.
LA  - eng
PT  - Case Reports
PL  - Croatia
TA  - Biochem Med (Zagreb)
JT  - Biochemia medica
JID - 9610305
RN  - 0 (Anticoagulants)
RN  - 9005-49-6 (Heparin)
RN  - 9007-41-4 (C-Reactive Protein)
SB  - IM
MH  - Anticoagulants/*administration & dosage/pharmacokinetics
MH  - C-Reactive Protein/*metabolism
MH  - Heparin/*administration & dosage/pharmacokinetics
MH  - Humans
MH  - Male
MH  - Partial Thromboplastin Time
MH  - Sepsis/*blood/*drug therapy
PMC - PMC8183121
OTO - NOTNLM
OT  - activated partial thromboplastin time
OT  - hemostasis
OT  - pre-analytical phase
OT  - unfractionated heparin
COIS- Potential conflict of interest None declared.
EDAT- 2021/06/19 06:00
MHDA- 2021/08/20 06:00
PMCR- 2021/06/15
CRDT- 2021/06/18 06:41
PHST- 2021/01/16 00:00 [received]
PHST- 2021/03/17 00:00 [accepted]
PHST- 2021/06/18 06:41 [entrez]
PHST- 2021/06/19 06:00 [pubmed]
PHST- 2021/08/20 06:00 [medline]
PHST- 2021/06/15 00:00 [pmc-release]
AID - bm-31-2-021003 [pii]
AID - 10.11613/BM.2021.021003 [doi]
PST - ppublish
SO  - Biochem Med (Zagreb). 2021 Jun 15;31(2):021003. doi: 10.11613/BM.2021.021003.