If a clot forms in our body and specifically in our blood vessels, there are ways the body tries to dissolve them and break them up to fragments. D-Dimer is such a fragment when clots undergo a natural process of fibrinolysis. So having low/normal levels of D-Dimers in our blood virtually rules out a clot in our blood vessels. That is the very reason your healthcare provider did what was best and had you screened for clots in the legs and deep vessels. If all was negative, then its all good. Having a high d-dimer is like having a high temperature (fever). As there can be many reasons why you have a fever, in the same way there are multiple reasons why you can have a high d-dimer. Its not necessarily just a clot that leads to high d-dimers in blood. Often infections, inflammations, autoimmune diseases (like rheumatoid arthritis), injections and rarely allergies can lead to a high d-dimer. That is why this test is not specific but it has a good negative predictive value, meaning a negative d-dimer gives us more information about you NOT HAVING a clot than a positive does about you HAVING one. So whoever was looking after you did the right thing by having you scanned for clots and making sure all is ok. Once your pneumonia (an infection and an inflammative process) settles and your back to your normal self. There is no reason why your D-Dimers will not be back to normal in no time. Hope you are all well by the time you get this information. Take care.