Thyroid 101

Thyroid 101

We have a gland in the front lower part of our neck (just below our Adam’s apple) that is in the shape of a tiny shield.  The thyroid provides a remarkable service as it regulates the metabolic rates of almost every tissue in the body.  Unfortunately, it is rather prone to malfunction, and this is more likely if an individual has relatives with thyroid disease.  The thyroid is controlled by the hypothalamic-pituitary system in your brain.  This extraordinary system samples the amount of thyroid hormone in the blood and then sends a chemical message (via TSH–thyroid stimulating hormone) to increase or decrease thyroid hormone production as needed.

Symptoms of thyroid disease are wide-ranging and often non-specific.  Thus, it is helpful when evaluating someone’s thyroid status to think in three different spheres:

The first sphere of concern is whether or not the amount of thyroid hormone that is being produced is appropriate. To answer this question, we most often inquire of the pituitary by sampling the blood level of TSH. If the TSH level is within normal range, then we usually stop there.  When the TSH is normal, we say the person is “euthyroid.”  If the TSH is elevated, it usually indicates that the thyroid gland is underproducing and the person in hypothyroid.  If the TSH is suppressed or low, then we suspect an overactive gland, a nodule, too much replacement therapy, or thyroiditis as causing hyperthyroidism.  Both situations require further medical evaluation.

The second issue is to decide whether or not the gland is enlarged (called a “goiter”).  Because of its strategic location in the neck, if it becomes enlarged, it can trigger “compressive symptoms” resulting in difficulty swallowing or breathing.  It is important to recognize these compressive symptoms and decide appropriate intervention.  This scenario can occur with or without an abnormal thyroid lab test.

The third sphere of concern even if there are no compressive symptoms or impaired function is whether there is any evidence of thyroid cancer.  Depending on the demographic of the person one is examining, the chances of finding a thyroid nodule can be as much as 70% (highest rate in elderly females).  These thyroid nodules can often be found incidentally on CT scans done to evaluate other conditions.  Statistically only 5% of thyroid nodules harbor a malignancy, and most of those are quite treatable.  Serial sonograms offer the ability to follow larger thyroid nodules over time without radiation exposure and help decide which ones may need fine needle aspiration, biopsy, or removal.

Nestled in behind the four corners of the thyroid lie the parathyroid glands—they must be saved for another blog.