What could cause my inr to be 1.9 last week, and 4.4 this week with no diet or medication changes? can lupus anticoag. do it?

INR: There are a bunch of things which can cause variation of inr which is why we monitor with at least every two week inrs when the patient is on warfarin. One of the things is also lab error. Lupus anticoag could contribute to an abnormal inr measurement. As inr of 4 can be associated with excess bleeding should get the situation clarified by your doc.

Changing INR : It is relatively common for inr to change even though a person keeps taking the same dose of Coumadin (warfarin) and is careful with diet, taking the same amount of green foods (salads, green vegetables). Lupus antibodies do raise inr but unless there is a change in the level of lupus antibodies, it would not affect the inr. Some individuals have a very labile (changing) inr for no apparent reason.