Where your DNA places you among other people, and the studies behind it.
Not tailored to your result, and not medical advice
Keep Iodine Intake In Range: Iodine is the raw material for thyroid hormone, and both too little and too much can push the gland into underactivity. Chronic deficiency leaves the thyroid unable to make enough T4, which raises TSH and can enlarge the gland into a goiter, and it remains the leading preventable cause of thyroid disease worldwide. At the other end, chronic over-iodization has been associated with increased odds of overt and subclinical hypothyroidism, because a large iodine load transiently suppresses hormone synthesis (the Wolff-Chaikoff effect) and some people fail to escape that block. Iodized salt, seafood, dairy and eggs cover ordinary needs, while seaweed is the most concentrated dietary source and the easiest one to overshoot with. Nutrients (PMC)
Eat Selenium-Rich Foods Regularly: Selenium is built into several proteins the thyroid depends on. Glutathione peroxidase clears the hydrogen peroxide generated during hormone synthesis, which protects thyroid cells, and the deiodinase enzymes that convert T4 into active T3 are also selenoproteins. A review of trace elements in autoimmune thyroid disease points to nuts and fish as the practical dietary sources. Supplementation trials have lowered thyroid peroxidase antibody levels, but they were small, short and used inconsistent selenium forms, so whether that changes who goes on to develop hypothyroidism is still unresolved. Frontiers in Immunology (PMC)
Keep Body Weight Stable: Obesity is associated with close to a twofold increase in the odds of a hypothyroidism diagnosis, but the direction of that link is not simple. Leptin rises in proportion to fat mass and increases hypothalamic TRH and pituitary TSH drive, and endocrinology reviews describe a mildly raised TSH alongside a normal free T4 in people carrying excess weight as a compensatory shift in the hypothalamic-pituitary-thyroid axis rather than gland failure. Weight gain appears to precede those modest TSH rises, and sustained weight loss can lead to normalization of thyroid indices. Keeping weight stable therefore matters for how the axis behaves, and a borderline thyroid result is something to work through with a clinician rather than to interpret alone. Journal of Mid-Life Health (PMC)
Take Slow-Building Symptoms Seriously: Hypothyroidism develops slowly, and NIDDK notes that symptoms may go unnoticed for months or even years. The common ones are fatigue, weight gain, trouble tolerating cold, joint and muscle pain, dry or thinning hair and skin, heavy or irregular periods, slowed heart rate and low mood. These overlap heavily with other conditions, which is why the diagnosis cannot be made from symptoms alone and rests on blood tests. Women and people over 60 are more likely to develop it, and a persistent cluster of these symptoms is a reasonable thing to raise with a clinician rather than to interpret yourself. NIDDK
Be Skeptical Of Thyroid Diets: Hashimoto's thyroiditis, an autoimmune disorder, is the leading cause of hypothyroidism, and its incidence is higher in women, with advancing age, and in iodine-sufficient populations. A 2026 review of adjunctive strategies found that recent meta-analyses showed no significant benefit from a gluten-free diet in Hashimoto's alone, and described its clinical utility as widely debated. Mediterranean-style eating looked promising as a complementary adjunct, but the studies behind it were small, and physical activity had modest and inconsistent effects on thyroid hormone levels while clearly improving quality of life. The review's own conclusion is that current data are insufficient to support definitive clinical recommendations, so these habits may improve how you feel without having been shown to change the underlying autoimmunity. Gland Surgery (PMC)
How much of this is genetic?
Genetics explains 65% of why people differ in this trait. The rest is environment, daily habits and chance.
Heritability estimate: Twin studies of autoimmune thyroid disease (Brix & Hegedus, Clin Endocrinol 2012)
Background and further reading
Hypothyroidism is a condition in which the thyroid gland does not make enough thyroid hormone (thyroxine, T4, and triiodothyronine, T3), slowing many of the body's metabolic processes. Overt hypothyroidism affects roughly 1-2% of adults, and milder subclinical forms are more common still, with prevalence rising with age. It is several times more common in women than in men. Common symptoms include fatigue, weight gain, cold intolerance, constipation, dry skin, hair thinning, low mood, and slowed heart rate, though many people have mild or nonspecific symptoms. In iodine-sufficient countries the leading cause is autoimmune Hashimoto's thyroiditis, in which the immune system gradually damages thyroid tissue. The condition is readily diagnosed with blood tests and effectively treated in most people.
Genetic Basis: Hypothyroidism and thyroid autoimmunity run strongly in families. Twin studies of autoimmune thyroid disease estimate that a large share of susceptibility is inherited, and circulating levels of thyroid-stimulating hormone (TSH) are themselves highly heritable. The trait is polygenic, meaning many common variants each nudge risk slightly. Genome-wide studies, including a large analysis of self-reported hypothyroidism, implicate immune-regulation genes shared across autoimmune conditions, such as the HLA region, PTPN22, CTLA4, SH2B3, and the thyroglobulin gene (TG), alongside thyroid-related genes including FOXE1, VAV3, and the TSH receptor (TSHR). These signals point to two intertwined mechanisms: a tendency toward autoimmune attack on the thyroid, and variation in how the thyroid axis is regulated.
Environmental Factors: Iodine intake is the single most important environmental influence: both deficiency and excess can impair thyroid function, and adequate but not excessive iodine is protective. Selenium status, pregnancy and the postpartum period, and certain medications (such as lithium and amiodarone) also affect risk, as do prior thyroid surgery or radiation to the neck. Age and female sex substantially raise susceptibility. Cigarette smoking has a complex relationship with thyroid autoimmunity. Because genetic predisposition and these exposures combine to determine whether the condition develops, a polygenic score describes tendency rather than certainty.
The published research behind your score, and the variants it draws on.
18 published scores from 9 studies
The hypothyroidism score combines 18 polygenic scores drawn from 9 published studies.
Chaker L, Bianco AC, Jonklaas J, Peeters RP Hypothyroidism. The Lancet (2017)
These traits are influenced by some of the same genes and variants as this one
WBC Count: The number of immune cells circulating in your blood.
Content updated August 2026.
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