I had a elevated CA 19.9 myself although not dramatically elevated. At the time i had undiagnosed hypothyroidism (Hashimoto's thyroiditis) and i found out a while later that elevated CA 19.9 can be due to thyroid disease so my results made sense. Hashimoto's thyroiditis is an autoimmune disease and the most common cause of hypothyroidism. And to add, hypothyroidism is one of the causes of ovarian cyst/s. Hashimoto's thyroiditis may show no symptoms earlier on in the disease.
Reading a case report, CA 19.9 was even up to 616U/ml due to Hashimoto's thyroiditis. The article: "Elevated CA 19.9 caused by Hashimoto's thyroiditis. Thyroiditis: Review of the benign causes of increased CA 19.9 Level"
Testing for a full thyroid panel is recommended - TSH, free T3, free T4 and thyroid antibodies - thyroid peroxidase antibody (TPOAb) and thyroglobulin antibody (TgAb).
Hi there!
If the test was done without any specific indication/ symptoms, I would suggest getting a repeat test done from another laboratory. If the CA 19-9 is still elevated, she would require a CT, to look for lesion in the pancreas/ GI and ovaries. It is also possible for the previously diagnosed cyst to cause the elevation. You may like to discuss the situation with her treating doctor.
Hope this helps.
Take care!