Low Molecular Weight Heparin Anti-Xa Level
(a.k.a Heparin -low molecular weight, Factor Xa, LMW, LMWH)
minimum sample volume required ~ 2.7ml
Tube type: 9NC
Special instructions
 
	
	For assessment of peak anti-Xa activity, a citrate sample should be taken 4 hours after subcutaneous administration.
If heparin accumulation is suspected, a trough sample at 12 hours may be useful.
Warning: Blood samples taken through in situ lines cannot be accepted as they are commonly contaminated with unfractionated heparin.
Haemolysed samples should not be tested.  Time limit for add on = 6 hours
Recommend using as per trust protocols or advice from clinical haematologist before requesting assay. Please inform the haematology laboratory prior to sending sample.
Urgent samples will be analysed within one hour from receipt of sample, laboratory must be informed prior to receiving sample.
		Contact Laboratory before requesting
	
	
	
Reference range 
	Once daily regime therapeutic range: 0.8-1.6 Twice daily regimes therapeutic range: 0.5-1.1
	
Units
	IU/ml
	
Turnaround Time
    1
			day
		
	
Department: Haematology
Clinical Application
	Please note: routine monitoring of anti-Xa activity is not recommended in clinically stable adults with uncomplicated disease. Monitoring may be warranted for patients with renal insufficiency, extremes of body weight, during pregnancy or in paediatrics.