Rapid Responses to:

EDITORIALS: Pierre-Marie Roy Diagnosis of venous thromboembolism BMJ 2009; 339: b2799 [Full text]

Rapid Responses: Submit a response to this article

Rapid Responses published:

Venous thromboembolism despite normal D-dimers

Jecko Thachil   (21 August 2009)

Running up Snowdon with venous thromboemboli

Mark D Coley   (30 August 2009)

Venous thromboembolism despite normal D-dimers 21 August 2009
Jecko Thachil, Research Fellow University of Liverpool Send response to journal: Re: Venous thromboembolism despite normal D-dimers	Dear Editor It is very heartening to note Professor Pierre-Marie Roy`s editorial comment about “assessing clinical probability first, then performing D- dimer tests” in the diagnostic strategy for venous thromboembolism. Over a hundred D-dimers requests are received in an average size hospital laboratory every week, where very often the results are positive. In most of these cases, it is not clear whether a clinical probability score was assessed before the test has been requested and as such whether the test was actually necessary in the first place. On the contrary, a normal D-dimer is often used as a stand-alone test without enough consideration given to the well-known clinical probability scores. This is despite reports where even major pulmonary emboli were detected despite normal D-dimer results, although clinical probability was moderate to high [1]. Venous thromboembolism can also occur despite normal D-dimer if the symptoms have been present for several days and if thrombi are small. Different laboratories use different assays and different cut-off points for the upper limit of normal, which can also cause difficulties with interpreting normal D-dimer results [2]. Hence, it is of utmost importance to examine the patient and assess the chances of thromboembolism using one of the several established scoring systems (e.g.; Well`s score for deep vein thrombosis or the revised Geneva score for pulmonary embolism), before taking into account the results of the D-dimer tests. 1. Gibson NS, Sohne M, Gerdes VE, Nijkeuter M, Buller HR. The importance of clinical probability assessment in interpreting a normal d- dimer in patients with suspected pulmonary embolism. Chest. 2008; 134: 789 -93. 2. Jennings I, Woods TA, Kitchen DP, Kitchen S, Walker ID. Laboratory D- dimer measurement: improved agreement between methods through calibration. Thromb Haemost. 2007; 98: 1127-35. Competing interests: None declared
Running up Snowdon with venous thromboemboli 30 August 2009
Mark D Coley, F1 Macclesfield District General Hospital, Victoria Road, Macclesfield, Cheshire, SK10 3BL Send response to journal: Re: Running up Snowdon with venous thromboemboli	As someone who was admitted to hospital (quite by accident) with multiple bilateral pulmonary emboli earlier this year, with emboli demonstrated on CTPA in all the major pulmonary arteries, I would be in favour of careful use of d-dimer tests at an earlier stage, even for people who do not have classic symptoms of venous thromboembolism. My d- dimer level on admission in April was 2628 mcgFEU/l and it was this result, a five-month history of not being able to run quite as fast as usual, a new onset right bundle branch block and prominent pulmonary vasculature on x-ray that led to a CTPA being ordered to provide a definitive diagnosis. I had presented to my GP about three months earlier saying my half marathon times were down slightly and that I had found it hard work doing the university running club's annual Christmas run up Snowdon. I had been worried I might have become anaemic for some reason and so was interested in having my haemoglobin level checked. I'd certainly had no classic symptoms of pulmonary emboli and could not recall at that time having anything that could be construed as a deep vein thrombosis in the previous months. My Hb came back at 15.5g/dl, instantly ruling out anaemia, and an ECG, peak flow and chest x-ray were all normal. I presumed exhaustion from final-year exam preparation was to blame. I had spoken to a number of doctors during my clinical attachments and all were intrigued as to what might have been going on. Although improving gradually, after a couple of months I returned to my GP and it was then that I was referred to the hospital for some lung function tests. I was admitted by chance before the appointment had come through following a fortuitous meeting with one of the A&E consultants. Had it been routine to measure d-dimer levels at the slightest hint of reduced exercise tolerance I'm sure the results would have been so suggestive of clot involvement that further investigation would have been warranted. Exercise tolerance was improving at the time of admission (I had completed another half marathon the month before), so I can only presume my d-dimer levels would have been higher in the preceding months. After diagnosis, and whilst trying to establish the cause in my own mind, I remembered that in October 2008 I had strained a calf muscle whilst running and awoken with cramp one morning a day or two later. I believe a small muscle knot, present for a few days, may have clamped a vein causing an asymptomatic calf vein thrombosis, which was the source of the emboli. I had forgotten all about this when I visited the GP a few months later. Had there been laboratory proof to hand that there were circulating breakdown products of blood clots I might have remembered what had happened 2-3 months earlier. The clinical picture, aided by a d-dimer result, would then have been more complete and further appropriate investigations then considered. Of course, mine may be a unique presentation, but I can't help feeling that my treatment may have begun several months earlier if d-dimer levels were assessed more routinely. As with many diagnostic tests in medicine they can be a useful tool if used appropriately. Competing interests: None declared