Is Hypothyroidism the Cause of Your Fatigue and Low Mood?

melakifrim
Jun 14
7 min read

Outline

I. Introduction

Common feelings: tiredness, low mood, busy schedules, stress, lack of sleep.
Persistent fatigue or mental fog: a sign of something more serious.
Hypothyroidism as a possible explanation.

II. What is Hypothyroidism?

Hypothyroidism: thyroid gland not producing enough hormones.
Thyroid hormones (T3 and T4): regulate metabolism, energy, mood.
Importance of these hormones for body function.

III. How Hypothyroidism Affects the Body

Slower metabolism, low energy, weight gain, cold sensitivity, mood changes.
Car engine analogy for thyroid’s role.
Symptoms: fatigue, weight gain, cold sensitivity, mood swings, brain fog, depression.

IV. Common Symptoms of Hypothyroidism

Symptoms: fatigue, weight gain, cold sensitivity, dry skin, brain fog, memory issues.
Women’s symptoms: menstrual cycle, fertility issues.
Mild symptoms: hard to notice, making diagnosis difficult.

V. Diagnosing Hypothyroidism

Blood tests: T3/T4, TSH levels.
TSH’s role in thyroid hormone production.
Challenges: mild symptoms, hard diagnosis.

VI. Treatment Options for Hypothyroidism

Levothyroxine: synthetic thyroxine (T4).
Restores thyroid function, energy.
Regular blood tests for hormone levels, medication dosage adjustments.

VII. Living with Hypothyroidism

Proper medication, regular check-ups: effective management.
Importance of medication instructions and healthcare visits.

VIII. Summary

Hypothyroidism: manageable with early detection and treatment.
Call to action: Ask your doctor to check your thyroid for early detection and treatment.

Introduction

Feeling tired or down lately? You're not alone. Many of us attribute low energy and mood to busy schedules, stress, or not getting enough sleep. While it's perfectly normal to have an off day now and then, feeling constantly drained or mentally foggy might be your body's way of signaling that something more serious is going on.1

One possible explanation is a condition called hypothyroidism. This happens when your thyroid, a small butterfly-shaped gland in your neck, doesn’t produce enough hormones to keep your body running smoothly. These hormones are responsible for regulating important functions like metabolism, energy levels, and mood. When hormone levels are low, it can leave you feeling sluggish, down, and even cause unexpected weight gain.8 7

If you're experiencing persistent fatigue, low mood, trouble concentrating, or changes in weight or temperature sensitivity, it might be a good idea to talk to your doctor. A simple blood test can check how well your thyroid is working, and if something's off, the good news is that it's treatable.8 1

Let’s break it down. “Hypo” means "under" or "below normal." The thyroid is a small, butterfly-shaped gland in your neck, and “-ism” just means it’s a condition. So, hypothyroidism is a condition when your thyroid isn’t working as well as it should.1

What is Hypothyroidism?

Imagine your body as a car, with the thyroid as the engine. Just like a car engine needs the right kind of fuel to run properly, your body depends on specific hormones called T3 (triiodothyronine) and T4 (thyroxine). These thyroid hormones act like fuel, keeping your body’s systems running smoothly and efficiently.2

One of their most important roles is managing your metabolism, which is the process your body uses to turn food into energy. These hormones also help regulate your heart rate, body temperature, brain function, and even how quickly your body uses oxygen and nutrients. In other words, they help keep everything in balance and working at the right speed.2

If your thyroid does not produce enough T3 and T4, it is like trying to drive a car with very little fuel. Things begin to slow down. You might feel unusually tired, gain weight even if you are eating the same, feel cold more often, or notice changes in your mood, memory, or skin. That is why the thyroid is so important to your overall well-being.2

How Hypothyroidism Affects the Body

Now, what happens when your engine isn’t getting enough fuel? Your car starts to slow down. It struggles to accelerate, uses up whatever fuel it has inefficiently, and basic functions like climbing a hill or turning on the headlights may become harder. Things just don’t run the way they should.8 7

This is very similar to what happens in your body when you have hypothyroidism. In this condition, the thyroid gland is not producing enough of the hormones your body needs to function properly. Without enough T3 and T4, your internal “engine” starts to lag. As a result, your metabolism slows down, and you may begin to feel tired all the time, even after a full night’s sleep. Your body may have trouble regulating temperature, leaving you feeling cold more often than others. You might notice weight gain, dry skin, or even a slower heart rate.5 8 7

Common Symptoms of Hypothyroidism

Because the thyroid hormones affect nearly every organ system, the symptoms of hypothyroidism can show up in many different ways. Some people experience brain fog or difficulty concentrating. Others might feel more anxious or depressed. For women, it can even affect the menstrual cycle and fertility.6

The good news is that hypothyroidism is manageable. Once diagnosed, it can often be treated with medication that replaces the missing hormones and helps your body get back to running at the right speed again.8 7

Hypothyroidism is quite common, especially among older people and women.1 Around 10% of Canadians aged 45 and older report having a thyroid disorder, with rates higher in women (16%) compared to men (4%).4 Thyroid issues are also more common in adults over 85, affecting about 16% of this age group.4 In fact, many people have a mild form of it, where symptoms are less noticeable but still there1. Some symptoms of this condition include slower metabolism, constant fatigue, weight gain, and depression.2

Diagnosing Hypothyroidism

Based on these symptoms, the doctor might send you to test the levels of your T3/T4 hormones.3 However, this might not be enough to detect the thyroid gland function properly, often making it hard for doctors to diagnose hypothyroidism and often misdiagnose it. This is because the T3/T4 hormones are just one part of how the body manages energy.3 To get a clear picture, doctors usually check another hormone, called TSH, which shows how hard the body is working to produce more thyroid hormones.3 The pituitary gland which is considered the master gland, is a small structure located at the base of the brain. It produces TSH, which makes the cells in thyroid gland manufacture and produce T3 and T4.3

Treatment Options for Hypothyroidism

Hypothyroidism is a manageable and treatable condition. Just like a car needs the right amount and type of fuel to run efficiently, your body needs a steady level of thyroid hormones to function at its best. When your thyroid is not producing enough of these hormones on its own, treatment can help bring your body back into balance.7 3

The most common and effective treatment is a daily medication called levothyroxine. This medicine is a synthetic version of thyroxine, also known as T4, one of the main hormones your thyroid normally produces. Once taken, your body absorbs it and uses it just like the natural hormone. Levothyroxine helps replace what your thyroid is missing, supporting the normal function of your metabolism and energy levels.7

Living with Hypothyroidism

For many people, taking this medication consistently allows them to feel more energetic, focused, and emotionally balanced. Over time, symptoms like fatigue, weight gain, brain fog, and feeling cold often begin to improve. Regular blood tests help your doctor adjust the dose so your hormone levels stay in a healthy range. It may take a little time to find the right dose for you, but once your levels are stable, most people are able to return to their normal daily activities and feel like themselves again.7

It is important to take the medication as prescribed and to follow up regularly with your healthcare provider. With proper care and monitoring, hypothyroidism can be controlled, allowing you to live a healthy and active life.1

Summary

Feeling constantly tired, down, or foggy may not just be due to stress or a busy lifestyle—it could be a sign of hypothyroidism, a condition where the thyroid gland does not produce enough hormones. These hormones, T3 and T4, are essential for keeping your body’s systems running smoothly, especially your metabolism, mood, and energy levels.

When thyroid hormone levels are too low, your body slows down. This can lead to symptoms like fatigue, weight gain, sensitivity to cold, depression, dry skin, and difficulty concentrating. Hypothyroidism is especially common in older adults and women, but it can affect anyone. Because the symptoms can be mild and vague, it often goes undiagnosed.

Diagnosis involves blood tests that check not only T3 and T4 levels but also TSH, a hormone from the pituitary gland that regulates thyroid hormone production. If diagnosed, hypothyroidism is treatable with daily medication like levothyroxine, which replaces the missing hormone and helps restore energy and balance.

With proper treatment and regular follow-up, most people can manage the condition and return to feeling like themselves.

So, if you’re feeling constantly tired, low, or just not yourself, it might be worth asking your doctor to check your thyroid—it could make all the difference.

References

Gottwald-Hostalek, U., & Schulte, B. (2021). Low awareness and under-diagnosis of hypothyroidism. Current Medical Research and Opinion, 38(1), 1–6. https://doi.org/10.1080/03007995.2021.1997258
Yasaman Pirahanchi, & Ishwarlal Jialal. (2018, December 17). Physiology, Thyroid. Nih.gov; StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK519566/
The Thyroid Solution: A Revolutionary Mind-Body Program for Regaining Your Emotional and Physical Health: Arem, Ridha: 9780345496621: Amazon.com: Books. (2024). Amazon.com. https://www.amazon.com/Thyroid-Solution-Revolutionary-Mind-Body-Regaining/dp/0345496620
Birtwhistle, R., Morissette, K., Dickinson, J. A., Reynolds, D. L., Avey, M. T., Domingo, F. R., Rodin, R., & Thombs, B. D. (2019). Recommendation on screening adults for asymptomatic thyroid dysfunction in primary care. CMAJ : Canadian Medical Association Journal, 191(46), E1274–E1280. https://doi.org/10.1503/cmaj.190395
Gaitonde D, Rowley K, Sweeney L. Hypothyroidism: an update. South African Family Practice [Internet]. 2012 [cited 2025 Apr 6]; 54(5):384–90. Available from: https://www.tandfonline.com/doi/full/10.1080/20786204.2012.10874256.
Chiovato L, Magri F, Carlé A. Hypothyroidism in Context: Where We’ve Been and Where We’re Going. Adv Ther [Internet]. 2019 [cited 2025 Apr 6]; 36(2):47–58. Available from: https://doi.org/10.1007/s12325-019-01080-8.
McAninch EA, Bianco AC. The History and Future of Treatment of Hypothyroidism. Ann Intern Med [Internet]. 2016 [cited 2025 Apr 6]; 164(1):50–6. Available from: https://www.acpjournals.org/doi/10.7326/M15-1799.
Wilson SA, Stem LA, Bruehlman RD. Hypothyroidism: Diagnosis and Treatment. afp [Internet]. 2021 [cited 2025 Apr 6]; 103(10):605–13. Available from: https://www.aafp.org/pubs/afp/issues/2021/0515/p605.html.
Judge A, Dodd MS. Metabolism. Essays in Biochemistry [Internet]. 2020 [cited 2025 Apr 6]; 64(4):607–47. Available from: https://portlandpress.com/essaysbiochem/article/64/4/607/226177/Metabolism.
Salas-Lucia F, Bianco AC. T3 levels and thyroid hormone signaling. Front Endocrinol [Internet]. 2022 [cited 2025 Apr 6]; 13:1044691. Available from: https://www.frontiersin.org/articles/10.3389/fendo.2022.1044691/full.
Dayan C, Panicker V. Management of hypothyroidism with combination thyroxine (T4) and triiodothyronine (T3) hormone replacement in clinical practice: a review of suggested guidance. Thyroid Res [Internet]. 2018 [cited 2025 Apr 6]; 11(1):1. Available from: https://doi.org/10.1186/s13044-018-0045-x.

‌Melak Ifrim, BSc (Hons) in Life Science with Distinction, is passionate about medical writing and as well as sharing scientific knowledge.

Assessed and Endorsed by the MedReport Medical Review Board