I have an elevated ddimer of .8, cut off is .49 my ct was clear except it noted atecelactasis of both lung bases & residual thymus help please! ?

False positive test: The D dimer is a frustrating test to doctors because it has a high false positive rate. When it is positive, you need a CT scan to make sure you don't have blood clots in your lung. It sounds like you had that, and don't have blood clots. Atelectasis occurs when the lungs compress. Get moving, that will go away. Residual thymus is a normal thing, like freckles.

DDimer confounding : There are many reasons why the DDimer may be elevated. Inflammation and a healing bruise are two examples of cases where the DDimer would likely be elevated without there are necessarily being a blood clot. The CT angiogram of the chest with the pulmonary embolism protocol that you apparently have done is a more sensitive and specific study for blood clots of the lung. Atelectasis is harmless.

See below: All laboratory results need to be interpreted in the clinical context and the doctor who ordered the tests is usually in the best position to do that. Having said that, a negative D-dimer result is good for ruling out blood cots, but a positive test is not very useful. The atelectasis in your lungs could be causing it.