Hypothyroidism, also known as an underactive thyroid, is a condition in which the thyroid (that's the butterfly-shaped gland located at the front of your neck) doesn't generate enough of its vital hormones to meet the body's needs. Hypothyroidism occurs in about 5 out of every 100 Americans over the age of 12, although many cases aren't diagnosed because the symptoms are so mild. There are many factors that increase the likelihood of developing hypothyroidism, including being female and having a family history of the condition. In this article, we'll look at the genetics of hypothyroidism, how it's diagnosed and treated, and how you can be vigilant about your thyroid health. (Source, Source)
What Is Hypothyroidism?
First, a little thyroid 101. The thyroid is part of your body’s endocrine system, which uses hormones to control things like metabolism, reproduction, energy, and your response to injury and stress. The pituitary gland, a pea-sized organ that's located at the base of your brain, produces a hormone called TSH. TSH prompts your thyroid to secrete triiodothyronine (T3), and tetraiodothyronine (thyroxine or T4), two other hormones that control your metabolism, in addition to other important functions. (Source, Source)
If you have hypothyroidism, it means there aren't enough hormones making their way into your body and regulating things like your body temperature, your period, how you bounce back from injuries, and how your food digests and processes. According to the Mayo Clinic, symptoms of hypothyroidism can include:
- increased sensitivity to cold
- dry skin
- weight gain
- puffy face
- muscle weakness, aches, tenderness, and stiffness
- pain, stiffness, or swelling in your joints
- heavier than normal or irregular menstrual periods
- thinning hair
Diagnosis and Treatment of Hypothyroidism
If your health care provider suspects your thyroid isn't functioning normally, they will take blood to assess your levels of TSH, the hormone that lets your thyroid know how much T3 and T4 to make. If you're making too much TSH, that's an indication of hypothyroidism. Why? Because the pituitary is releasing increased amounts of TSH to stimulate the thyroid to produce more of its hormones. Elevated TSH suggests the thyroid is not responding. (Source)
There are actually two types of hypothyroidism:
- overt hypothyroidism, when your TSH levels are high and your levels of T4 are low, and
- subclinical hypothyroidism, when your TSH is high, but the rest of your thyroid hormones are fine.
Overt hypothyroidism needs to be treated immediately, but the jury is still out in some corners of the medical community as to whether everyone with subclinical hypothyroidism needs treatment. (Source, Source)
When hypothyroidism is left untreated, in time it may result in fertility challenges, heart issues, and birth defects. While there’s no cure for hypothyroidism, it may be treated with daily doses of synthetic thyroid hormone, which is monitored and adjusted by a health care provider.
Symptoms of hypothyroidism tend to start out mild and intensify over time, so it's possible you wouldn't notice them right away. In fact, according to the American Thyroid Association, there's no single set of symptoms that always occurs in people who have hypothyroidism, and it's important to be aware that many of the symptoms listed above also occur in people who have other medical conditions. (Source)
Risk Factors for Hypothyroidism
As we mentioned up top, women are 5 to 8 times more likely to develop hypothyroidism. (Source)
Additional risk factors include:
- a previous thyroid problem (like a goiter, an enlarged thyroid that causes visible swelling in the neck)
- surgery or radioactive iodine to address a thyroid problem
- radiation treatment on the thyroid, neck, or chest
- pregnancy within the previous 6 months
- other health problems such as Turner syndrome, celiac disease, diabetes, lupus, or rheumatoid arthritis
- family history of thyroid disease
It’s important to share with your health care provider as much as you know about your family’s medical history — especially when it comes to thyroid issues — because in some cases there may be a genetic connection.
Genetics and Hypothyroidism
Many studies suggest an individual’s thyroid hormone and TSH levels are determined genetically. Additionally, a study published in Clinical Endocrinology found that first degree relatives (parents, siblings, children) of patients with hypothyroidism due to Hashimoto’s disease — a common cause of autoimmune thyroid dysfunction — have an overall 9-fold higher risk of developing it as well. In the same study, women were more likely than men to have thyroid antibodies (indicating attack by their immune system) and hypothyroidism due to Hashimoto’s thyroiditis. (Source, Source)