Hi all I have a question about the d dimer well a few years ago I had pain in my leg and went to hospital they did a d dimer which was positive they then gave me a scan which was clear but what I wondered was does any one know why else this could of been positive if scan was clear .when this happened I didn't even know I had ApS so didn't think to ask questions.
Xx
Hi Moonbug,
What type of scan/where did they scan? Maybe they're missed the clot or it could have moved before they looked for it? When my D dimer was positive they found clots in my lungs but when they scanned my legs for DVT they found none. I think certain things like inflammation, liver problems etc can give false positives. I'm sure there are more experienced Hughies that will chime in.
Hi Moonbug
It is possible as Sassy suggests that clot had moved or they were looking in wrong place, also possible to have false positive and false negative D Dimer tests.
I had dvt and PE, clot had already moved from leg to lungs by the time scan was organised and my D Dimer was negative!!!
Aps a mystery within an enigma?!?!!
Take care gentle hugs love Sheena xxxxx 
Hi Moonbug,
It is possible to have a false negative D-dimer test as this had happened to me on each occasion the docs used a D-dimer test prior to me finally coughing up blood and then they gave me a VQ scan and discovered multiple PE's. Consequently no doctor ever uses a D-dimer test on me anymore. I did read that in some people who have anti-coagulated blood the D-dimer test will give a false negative result.
As far as a false positive result, it may do that also, however when I was researching my own false negative result I also read that sometimes other things can effect a D-dimer test.
This is where I got my information if you wanted to have a read,
Yes, all of the above, pretty well covers your query. I have failed all tests for APS, despite my multiple clots with first pregnancy. Mary F x
D Dimer is frequently high without having any clots. I know mine tends to run high (positive) on a day to day basis.
Here is a very general explanation from Wikipedia giving some causes:
Various kits have a 93-95% sensitivity and about 50% specificity in the diagnosis of thrombotic disease.[7]
False positive readings can be due to various causes: liver disease, high rheumatoid factor, inflammation, malignancy, trauma, pregnancy, recent surgery as well as advanced age[citation needed]
False negative readings can occur if the sample is taken either too early after thrombus formation or if testing is delayed for several days. Additionally, the presence of anti-coagulation can render the test negative because it prevents thrombus extension.
Likelihood ratios are derived from sensitivity and specificity to adjust pretest probability.
In interpretation of the d-dimer, for patients over age 50 a value of ageX10 may be abnormal.[8][9]
Vitamin D
Vit D
Vitamin D and APS, some interesting reading..
:D good news at last 
APS study with vitimin D
