Thyroid nodules are very common, especially as we get older. It is very common for thyroid nodules to be discovered on imaging for parathyroid disease. Do the nodules need to be biopsied prior to parathyroid surgery? It depends. I would want to see more information about the nodule before giving a recommendation.

Most thyroid nodules are completely benign; some nodules will contain cancer. If you do have thyroid cancer, then it is better to diagnose that prior to parathyroid surgery so that both the parathyroid disease and thyroid disease can be treated at the same time. The best way to rule out thyroid cancer is with a fine needle aspiration (FNA) biopsy of the nodule. During this procedure, a thin needle is inserted into the thyroid nodule and some cells of the nodule are sucked into the needle. These cells are then evaluated under the microscope and evaluated for features suggesting cancer. Sometimes the findings are equivocal, and further testing is needed, but the FNA biopsy is often very helpful.

Not all thyroid nodules need to be biopsied, though. Some nodules are very clearly benign on ultrasound, and do not need biopsies. Radiologists have specific ways to report about thyroid nodules, and should give a TIRADS score for each nodule. This score adds up the points for different features seen with ultrasound (for example, whether tiny calcifications were seen within the nodule). The TIRADS (or TR) score is then used to estimate the risk of cancer. The risk of cancer rises as the TR score goes up. If a nodule is deemed TR1, it is almost surely benign. TR2 has a very very low chance of cancer. TR1 and TR2 nodules do not need to be biopsied. TR3 is most likely benign, but there is some risk of cancer. Once you get to TR5, the likelihood of containing cancer is high. Whether the nodule needs to be biopsied depends on the TR score as well as the size. The larger the nodule, the more likely you will need a biopsy.

Current guidelines recommend getting an FNA biopsy on 2.2 cm nodule if they are TR4 or TR5. If your nodule has a concern for malignancy, then it makes sense to get an FNA biopsy prior to parathyroid surgery. If your nodule is more likely benign, then I would not recommend a biopsy.

One more thing: I have seen many cases in which the parathyroid adenoma has been called a “thyroid nodule” on ultrasound. If you biopsy a parathyroid adenoma, it can make the parathyroid operation much more difficult. I discourage ever getting parathyroid tumors biopsied. If the “thyroid nodule” has features of a parathyroid tumor (e.g. it is hypoechoic and located on the back side of the inferior thyroid lobe), then I am less eager to get that biopsied.

You do not need to have the nodule biopsied prior to a consultation with a surgeon. Your labs indicate primary hyperparathyroidism so you are going to need parathyroid surgery. If you need thyroid surgery as well, it can be dealt with during the same operation. If I think that a nodule should be biopsied prior to surgery, I will let patients know that.