Last reviewed: May 12, 2026 Last updated: May 12, 2026

Written by: Jay Hastings , CEO of PlexusDx

Jay Hastings is the CEO of PlexusDx, a precision health company focused on genetic testing, blood biomarker insights, and personalized wellness recommendations. He has more than 20 years of experience across healthcare innovation, genomics, laboratory operations, healthcare investing, and strategic finance. His work has included scaling healthcare startups, leading CLIA lab integrations, and helping expand consumer access to precision health tools.

Medically reviewed by: Jayden Lee, PharmD, EMBA

Jayden Lee, PharmD, EMBA, is the PlexusDx Medical Science Liaison with a PharmD and MBA specializing in pharmacogenomics and clinical product development, with a proven ability to bridge the gap between genomic research and practical patient outcomes. Dr. Lee has more than 10 years of professional experience in clinical pharmacy, academia, and research.

How TSHR Variants Affect Thyroid Health

The thyroid gland produces hormones that regulate metabolism, energy, body temperature, and many other processes. The TSHR gene helps thyroid cells respond to thyroid stimulating hormone, or TSH, which tells the thyroid to make and release hormones. Changes in the TSHR gene can alter how the thyroid responds to TSH and may influence risk for low thyroid hormone and thyroid enlargement, commonly called hypothyroidism and goiter.

What this means for you

Genetic differences are one piece of your overall thyroid health picture. Lifestyle, diet, medications, autoimmune conditions, and nutrient status also play major roles. This article explains the typical effects linked to the common TSHR variant rs1991517, practical steps to support thyroid function, and recommendations for testing and follow up.

Two effect alleles (GG) — higher genetic risk for lower TSH and hypothyroidism

If you have the GG genotype for rs1991517, you carry two copies of the effect allele. This genotype is associated with genetically lower TSH levels and a higher risk for developing hypothyroidism and goiter. The TSHR gene change may affect how well thyroid cells respond when TSH signals them to produce thyroid hormones.

Practical suggestions

  • Ensure adequate iodine intake from iodized salt, seafood, dairy, and seaweed in moderation. Avoid excessive iodine intake.
  • Include selenium rich foods such as Brazil nuts, eggs, and seafood to support conversion and activation of thyroid hormones.
  • Get zinc from pumpkin seeds, nuts, and lean red meat to aid thyroid hormone metabolism.
  • Support vitamin A and D status through diet, sensible sun exposure, and supplementation if advised by your healthcare provider.
  • If iodine intake is low or you have symptoms of hypothyroidism, consider limiting large quantities of goitrogenic foods like broccoli, cabbage, soy, and cassava until you talk with a clinician.
  • Manage stress with relaxation practices, maintain regular sleep patterns, and reduce exposure to potential endocrine disruptors such as certain plastics and personal care products.
  • Discuss baseline and periodic thyroid function testing with your healthcare provider, especially if you notice fatigue, cold sensitivity, unexplained weight gain, dry skin, or changes in mood or cognition.
One effect allele (CG) — modestly increased risk for lower TSH and hypothyroidism

If you have the CG genotype for rs1991517, you carry one copy of the effect allele. This genotype is associated with genetically lower TSH levels and an increased risk for hypothyroidism and goiter, but the effect size is generally smaller than having two effect alleles.

Practical suggestions

  • Maintain balanced iodine intake using iodized salt and a variety of iodine containing foods such as seafood and dairy. Avoid very high iodine doses unless directed by a clinician.
  • Include selenium rich foods like Brazil nuts and eggs and zinc rich foods like pumpkin seeds and lean meats to support hormone activation and metabolism.
  • Support vitamin A and D through diet, safe sun exposure, and testing or supplementation if indicated.
  • If you have low iodine or symptoms such as fatigue, cold intolerance, or weight gain, consider moderating intake of goitrogenic foods and seek medical evaluation.
  • Prioritize stress reduction, good sleep, and reducing exposure to endocrine disrupting chemicals in everyday products.
  • Consider regular thyroid testing if you develop symptoms or have other risk factors, and discuss results with your healthcare provider.
No effect alleles (CC) — typical genetic risk for thyroid function

If you have the CC genotype for rs1991517, you carry two copies of the non-effect allele. This genotype is associated with typical thyroid function and normal TSH levels. Your TSHR variation does not increase your genetic predisposition to hypothyroidism or goiter based on this variant.

Practical suggestions

  • Continue balanced nutrition including iodine from seafood and iodized salt, selenium from Brazil nuts and eggs, and zinc from nuts and seeds.
  • Maintain healthy lifestyle habits for long term thyroid support: quality sleep, stress management, and limiting exposure to endocrine disruptors.
  • Routine thyroid testing is not required solely because of this genotype, but discuss testing with your healthcare provider if you develop symptoms or have other risk factors.

Diet and nutrients that support healthy thyroid function

  • Iodine: Essential for thyroid hormone production. Sources include iodized salt, seafood, dairy, and small amounts of seaweed. Avoid very high doses unless advised by a clinician.
  • Selenium: Important for enzymes that activate thyroid hormones. Sources include Brazil nuts (one to two nuts per day can provide significant selenium), eggs, seafood, and lean meats.
  • Zinc: Supports thyroid hormone synthesis and signaling. Sources include pumpkin seeds, nuts, beef, poultry, and lentils.
  • Vitamins A and D: Support thyroid hormone action and immune health. Include colorful vegetables, liver in small amounts if appropriate, fortified foods, fatty fish, and safe sun exposure. Consider testing and supplementation if levels are low.
  • Goitrogenic foods: Vegetables such as broccoli, cabbage, kale, and soy contain compounds that can interfere with thyroid hormone production in the setting of low iodine. Cooking these foods reduces their goitrogenic effect. If iodine intake is adequate, typical servings are usually fine for most people.

Supplement considerations

  • Do not start high dose iodine or selenium supplements without medical supervision. Excessive amounts can worsen thyroid problems.
  • If testing shows low vitamin D, a healthcare provider may recommend supplementation.
  • If you take supplements, inform your healthcare provider to avoid interactions with medications or thyroid tests.

Lifestyle habits to support thyroid health

  • Manage stress with mindfulness, breathing exercises, yoga, or regular physical activity, since chronic stress can influence hormone regulation.
  • Prioritize 7 to 9 hours of sleep per night to support hormonal balance and metabolic health.
  • Reduce exposure to endocrine disrupting chemicals by choosing glass or stainless steel over plastic for food storage, selecting personal care products with fewer synthetic chemicals, and minimizing consumption of highly processed foods.
  • Maintain a balanced weight through regular activity and whole food based nutrition, and seek guidance if rapid weight changes occur.

When to get tested and who to talk to

Talk to your healthcare provider if you have symptoms such as persistent fatigue, cold sensitivity, constipation, dry skin, unexplained weight gain, hair thinning, or changes in mood. Common tests include TSH, free T4, free T3, and thyroid antibody panels when autoimmune thyroid disease is suspected. Your provider can help interpret results in the context of symptoms, medications, and other health conditions.

PlexusDx provides educational information about genetic tendencies. This content is not medical advice. Always consult your healthcare provider for medical evaluation, testing, and treatment decisions.

If this genetic variant is present in your PlexusDx results, the following tests and reports are commonly used to explore it further:

🧬 Genetic Tests:

🧪 Blood Tests:

📄 Genetic Report:

Frequently Asked Questions About Thyroid and TSHR rs1991517

How does the TSHR rs1991517 variant affect thyroid hormone levels and symptoms?

The TSHR gene helps thyroid cells respond to TSH so they can produce and release thyroid hormones. The common variant rs1991517 is associated with genetically lower TSH levels, which can increase risk for hypothyroidism and thyroid enlargement (goiter). In practical terms, people with higher-risk genotypes may be more likely to develop symptoms like persistent fatigue, cold sensitivity, constipation, dry skin, unexplained weight gain, hair thinning, or mood/cognitive changes.

What do rs1991517 genotypes (GG, CG, CC) mean for hypothyroidism and goiter risk?

GG (two effect alleles): higher genetic risk for lower TSH, hypothyroidism, and goiter. CG (one effect allele): modestly increased risk, typically smaller than GG. CC (no effect alleles): typical genetic risk for thyroid function, with rs1991517 not associated with increased predisposition to hypothyroidism or goiter. Your overall risk still depends on other factors like autoimmune conditions, nutrient status, medications, and lifestyle.

What diet, nutrients, and testing steps support thyroid health if I have a higher-risk TSHR genotype?

Focus on balanced intake of iodine (iodized salt, seafood, dairy; avoid very high doses), selenium (e.g., 1–2 Brazil nuts/day, eggs, seafood), and zinc (pumpkin seeds, nuts, lean meats/lentils). Support vitamin A and D through diet and safe sun exposure, and consider testing if levels may be low. If iodine intake is low or you have hypothyroid symptoms, you may want to moderate large quantities of goitrogenic foods (like broccoli, cabbage, soy, and cassava) until you discuss with a clinician. For evaluation, talk to your healthcare provider about thyroid testing such as TSH, free T4, free T3, and thyroid antibody panels if autoimmune thyroid disease is suspected.

What tests can help me learn more about Thyroid and TSHR rs1991517?

The Hormone, Thyroid, and Reproductive Health Genetic Test delivers over 85 personalized genetic insights through a comprehensive Hormone & Fertility Genetic Report, explaining inherited tendencies related to hormonal balance, reproductive function, and endocrine signaling. The Mens Hormone and Fertility Health Genetic Report translates your results into personalized, actionable guidance. Your healthcare provider can also recommend targeted blood tests based on your specific pathway results and health history to complement your genetic insights with current biomarker data.

Medical and Editorial Standards

Medical review process: This article was reviewed for medical accuracy, scientific clarity, evidence alignment, and appropriate discussion of genetics, medications, supplements, biomarkers, and health-related claims.

Sources and evidence: PlexusDx educational content is developed using peer-reviewed research, clinical literature, reputable medical references, and, where applicable, public health or regulatory guidance. References are included at the end of the article when scientific, medical, or health-related claims are discussed.

Commercial transparency: PlexusDx offers genetic testing, blood biomarker testing, personalized supplement recommendations, and related precision wellness services. Product mentions are intended to help readers understand available options and should not be interpreted as medical advice.

Important disclaimer: PlexusDx educational content is for informational purposes only and should not be used as a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making decisions about medications, supplements, genetic testing, lab testing, or health-related care.