A young patient has has a new onset of persistent aPTT derangement, around 20 seconds above the upper limit of the reference range. No spontaneous bleeding episode but increased bleeding post venipuncture, one-off episode epistaxis, oral mucosal bleeds on and off, hematuria on and off, none of which can be explained by other definitive local causes. Full evaluation and complete coagulation assessment has been non-revealing. LA absent, no coagulation factor deficiencies or inhibitors found. Mild elevation of Homocysteine (30) was the only other laboratory abnormality related to coagulation, but has not had any clinical significance. Liver panels, PT/INR, platelets etc all unremarkable.
Patient has earlier undergone surgical procedures including teeth extraction uneventfully, with old coagulation reports being normal.
What could be the cause? Any articles relating to unexplained coagulation abnormalities and their clinical significance?
Does the patient take an Aspirin ?
Does the patient have factor V, VIII or IV deficiency ?
Ahmed Osama Hassen - Thanks for your reply!
No anticoagulant or anti-platelet medication.
Vitamin K deficiency would affect factors II, VII,IX and X so would not cause an isolated aPTT derangement, rather would be manifested as a prolonged PT and INR which are normal in this case. Coagulation factors II, VII, VIII,IX, X, XI are within normal range. Its a bit puzzling.
Link : https://litfl.com/isolated-elevated-aptt/
Isolated Elevated APTT
by Dr Chris Nickson, last update April 25, 2019
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OVERVIEW
- APTT measures the activity of the intrinsic and common pathways of coagulation
CAUSES
- Lupus anti-coagulant (antiphospholipid syndrome)
- Heparin exposure
- Haemophilia A and B (Factor VIII and IX deficiency respectively)
- Factor XII deficiency
- Factor XI deficiency
- Contact factor deficiency e.g. prekallikrein (not clinically important)
- Artefact (incorrect amount of blood in the tube)
INVESTIGATIONS
- Repeat test (to exclude artefact)
- Coag screen and fibrinogen (if normal then excludes DIC)
- Heparinase assay or antibodies
- Mixing test with normal plasma (excludes clotting factor deficiency)
- Factor assay (excludes clotting factor deficiency)
- anticardiolipin antibody (antiphospholipid syndrome)
- Thrombin time and reptilase time (used to establish whether heparin contamination occurred: reptilase not prolonged in heparin contamination but thrombin time is)
- Lupus anticoagulant tests (antiphospholipid syndrome) -> APTT, dilute Russell viper venom time, kaolin clotting time, dilute PT, Textarin time, Taipan time.
- Link address : https://litfl.com/isolated-elevated-aptt/
Thank you Sir, that article covers the investigations for aPTT derangement very concisely. Performed all of them and got a hematologists consult. unfortunately still looking for an answer.