When pregnant my older sister had big panel of antibody studies done due to multiple miscarriages. if abnormal, will she have lifelong problem?

Yes: If she has a positive anti-phospholipid antibody , which can cause miscarriages, she may have a life-long propensity to clotting, but this condition may be managed. This positive antibody may occur alone, or in association with other autoimmune cconditions, such as lupus. These conditions can vary widely in their severity.

Agree with Dr. M.: Some antibodies are life long problems but there are treatments for most auto-antibodies, including those causing miss-carriages.