The small, butterfly-shaped thyroid gland is in the neck and packs a punch when it comes to regulating the body’s metabolism, energy production, body temperature, heart rate, and many other essential bodily functions. But what happens when it’s no longer balanced? What happens when it is working too hard or not hard enough? Let’s explore the difference between two common thyroid disorders- hypothyroidism and hyperthyroidism.

Hypothyroidism: An Underactive Thyroid

Hypothyroidism has to do with the thyroid’s inability to produce enough thyroid hormone.¹ The most common cause of hypothyroidism is Hashimoto’s disease, an autoimmune disorder where antibodies attack the thyroid gland.² There is a deficiency in the T4 hormone (thyroxine) that causes an elevation in thyroid-stimulating hormone (TSH). TSH regulates thyroid hormone production. Because of the deficiency, the body compensates by trying to produce more thyroid hormone, hence the elevated TSH. When T4 is low, the body slows down. This results in fatigue, weakness, weight gain, cold intolerance, dry skin, constipation.² Additional symptoms may include depression or low mood, hair thinning, and a slowed heart rate. Hypothyroidism is more common than hyperthyroidism and occurs more often in females.

Hypothyroidism Is Becoming More Common

Hypothyroidism is one of the most common endocrine disorders in the United States, and recent research suggests its prevalence is increasing. Historically, hypothyroidism was estimated to affect approximately 4.6% to 5% of the U.S. population. However, newer analyses using National Health and Nutrition Examination Survey (NHANES) data and large insurance claims databases found that prevalence increased from approximately 9.5% in 2012 to 11.7% in 2019, indicating that more than 1 in 10 Americans may now be affected by some form of hypothyroidism.³

Researchers estimate that nearly 19 million Americans are living with hypothyroidism, with women accounting for the majority of diagnosed cases.⁴

Although the number of people diagnosed with hypothyroidism continues to rise, the exact reasons remain unclear. Experts believe several factors may contribute, including:

• Increased awareness and screening efforts
• An aging population
• Greater recognition of subclinical thyroid disease
• Rising rates of autoimmune conditions such as Hashimoto’s thyroiditis

However, current evidence has not identified a single definitive cause for the observed increase in prevalence. Additional research is needed to better understand the factors driving these trends.³

These findings highlight the importance of early recognition, routine monitoring in high-risk populations, and patient education regarding symptoms that may otherwise go unnoticed.

Hyperthyroidism: An Overactive Thyroid

On the other hand, hyperthyroidism is the complete opposite. The most common cause of hyperthyroidism is Graves’ disease which is also an autoimmune disorder where antibodies stimulate increased thyroid production of the T4 hormone.² There is an increase in T4 hormone that causes TSH to be low. When T4 is high, the body speeds up. This results in anxiety, tremor, fatigue, weakness, weight loss, heat intolerance, increased sweating, frequent bowel movements, difficulty sleeping, and in some cases a rapid or irregular heartbeat.² Hyperthyroidism is more common among females of older age.

Diagnosis and Treatment

Making an accurate diagnosis is crucial as both conditions involve the thyroid, and some symptoms may appear similar even though there is still a difference. Measuring thyroid hormone levels via laboratory blood tests will confirm diagnosis.

Treatment for hypothyroidism involves thyroid hormone replacement such as levothyroxine (Synthroid®, Levoxyl®, Unithroid®), which remains the first-line treatment, or liothyronine (Cytomel®) in select situations. Treatment for hyperthyroidism may involve antithyroid medications such as methimazole, which is generally preferred as first-line therapy for most patients, or propylthiouracil (PTU), which is typically reserved for specific situations such as the first trimester of pregnancy or thyroid storm. Additional treatment options include thyroid surgery or radioactive iodine therapy to reduce thyroid hormone production.²

Pharmacists play a role in managing these disorders through collaboration with other healthcare providers. Such actions involve providing dosing guidance, counseling patients on medication usage and side effects, offering recommendations for symptom management, and addressing potential complications of not treating the disorder that could result in cardiovascular and fertility issues alike. They can monitor drug interactions and educate patients on the importance of medication adherence. Pharmacists may also educate patients on proper administration of thyroid medications, identify symptoms that warrant further medical evaluation, reinforce routine monitoring recommendations, and support patients in managing chronic thyroid conditions over time.

In Summary

Hypothyroidism and hyperthyroidism- two sides of an imbalanced thyroid gland have a profound effect on the body. Appropriate treatment and ongoing monitoring are important because untreated thyroid disorders may contribute to cardiovascular complications, fertility concerns, bone health issues, and reduced quality of life. To understand and manage each condition, appropriate understanding is required as to what makes them different, what symptoms to watch out for, and how to treat each condition accordingly to achieve thyroid balance once more.

Original Author: Midrara Kashmari

Editorial Update (June 2026): Elizabeth Rodriguez

RxPharmacist Team

References:

1. Hypothyroidism vs. hyperthyroidism: What’s the difference? NIH MedlinePlus Magazine. https://magazine.medlineplus.gov/article/hypothyroidism-vs-hyperthyroidism-whats-the-difference.
2. Hyperthyroidism vs. Hypothyroidism: Here’s How to Tell The Difference | Hartford HealthCare | CT. hartfordhealthcare.org. https://hartfordhealthcare.org/about-us/news-press/news-detail?articleid=32994&publicId=395.
3. Wyne KL, Nair L, Schneiderman CP, et al. Hypothyroidism Prevalence in the United States: A Retrospective Study Combining National Health and Nutrition Examination Survey and Claims Data, 2009–2019. Journal of the Endocrine Society. 2023;7(1):bvac172. https://doi.org/10.1210/jendso/bvac172
4. American Thyroid Association. Clinical Thyroidology for the Public. September 2025. Hypothyroidism prevalence and population estimates in the United States. Available at: https://www.thyroid.org