What does abnormal uptake on a thyroid nuclear scan mean?

Low or high?: Low uptake could indicate hypothyroidism, while high uptake might indicate hyperthyroidism (grave's disease). The test (scan) you had would have also detected a hot nodule, which would need to be surgically removed. But it does not appear by your question that this is of concern.

Several things: The result of a thyroid uptake test could be abnormally increased or decreased. In the usa, the normal thyroid uptake range is approximately 10-30% at 24 hours. An increased result may be due to various reasons including: grave's disease, multinodular toxic goiter or hashitoxicosis. A decreased uptake could be due to subacute thyroiditis, iodine or amiodarone induced thyrotoxicosis among others.

See below: High uptake suggest hyperthyroidism and low uptake may suggest hypothyroidism and its multiple variations. See your doctor to discuss results of the test.

Various possibilitie: Thyroid uptake must be interpreted with the results of some blood tests such as TSH , T3 (liothyronine) and T4 values and the clinical context. Usually high uptake ( more than 30%) is related to hyperthyroidism ( graves disease, thyroiditis..) and decreased uptake to hypothyroidism. However, there are various possibilities and all these data should be interpreted together. You should ask your physician.