Seven possible signs of an underactive thyroid

Doctor examines young woman's thyroid
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What are the tell-tale signs of an underactive thyroid – a chronic condition in which your thyroid gland does not produce enough hormones for your body’s needs?  Symptoms can range from a lack of energy to creeping weight gain, although it’s important to stress that these particular symptoms could also relate to a host of different health problems or simply be a sign that you need more quality rest.

So how do you recognize that your thyroid gland is causing your health problems? Thyroid hormones are directly responsible for how your body uses and stores energy. When their levels are low, your metabolism slows down, which affects nearly every organ in your body and this may be caused by anything from damage to a thyroid gland, autoimmune disorders and lifestyle factors.

If you are worried that you may have thyroid problems, then be sure to read on. But a word of warning: don’t go through this list, identify symptoms and come to your own conclusion. If you believe you may be displaying signs of an underactive thyroid, then you must seek help from a medical professional who can provide a diagnosis.

Dr. Rebecca Breslow
Dr. Rebecca Breslow

Dr. Rebecca Breslow is a physician, researcher, and writer.  A graduate of Yale University, she did her medical training at Harvard Medical School, Brigham and Women’s Hospital, and Boston Children’s Hospital.  She was a practicing physician in academic medicine for 17 years, during which time she authored numerous publications for academic and lay audiences.  Currently, she focuses on freelance medical writing and editing to help make medical, health, and wellness information accessible to a broad audience. 

You struggle to lose weight

There are many reasons why you may struggle with weight loss. You may not be exercising enough or you may be eating too many calories. Maybe you’re suffering from poor sleep or some of your medications are interfering with your metabolism. 

If your struggle is difficult to explain, you’ll want to rule out hypothyroidism. A problem with weight maintenance is one of the most common signs of an underactive thyroid and there are stark reasons for this.

As mentioned earlier, thyroid hormones regulate how your body uses and stores energy. According to a review in Physiological Reviews, reduced levels of thyroid hormones are associated with a slower metabolism, which reduces resting energy expenditure (the number of calories burnt at rest) and can lead to weight gain.

Thyroid hormones also help to regulate your appetite, according to a study in the Journal of Thyroid Research, so an underactive thyroid may cause you to experience more hunger, even if you do not need to eat more food.       

woman's feet standing on a pair of scales

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You’re tired all the time

Fatigue is a very broad symptom, and it may signal many different health problems. It can be a direct result of chronic stress, a lack of sleep, certain medications and physical exertion, but rest usually helps you to rejuvenate. 

If your tiredness does not seem to have a plausible explanation, however, and a good night’s sleep is making little difference to your energy levels, it may be a sign of hormonal problems. 

Indeed, fatigue is considered to be one of the primary signs of an underactive thyroid. In a study published in the European Journal of Endocrinology, fatigue was reported as a symptom in 52% of adult patients, and 31% of pediatric patients. 

Why is that the case? As mentioned previously, thyroid hormones are directly responsible for energy metabolism. With low metabolism, your body will try to conserve as much energy as possible.

You can’t stand the cold

Have you been more sensitive to cold temperatures recently? Having trouble tolerating cold is another sign of an underactive thyroid. Your body is rather adept at regulating your temperature. Whenever it senses that the temperature is dropping, it burns more calories to generate heat. 

Most of the time, it is a seamless process that is barely noticed on a daily basis. But when thyroid hormones don’t work as they should and your metabolism slows down, your ability to keep yourself warm also decreases. According to a study in the Journal of General Internal Medicine, approximately 40% of people with hypothyroidism feel more sensitive to cold than they used to. 

Woman Wrapped Having Drink While Standing At Home

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Your muscles and joints ache

Muscles and joints will ache for various reasons. According to an article in the American Family Physician journal, muscle problems can be down to a host of infectious, neurologic, inflammatory, rheumatologic, genetic, metabolic, electrolyte-induced, or drug-induced causes. But if everything seems to be in perfect condition, yet you find yourself struggling with aches and pains, you may need to check your thyroid hormones. 

But why? People with hypothyroidism have an altered metabolism that is more geared towards catabolism rather than anabolism. Catabolism is a state of breaking down muscle tissue for energy, while anabolism helps you gain muscle. With low thyroid hormone levels, your muscle mass and strength may decrease, leading to feelings of pain and weakness. 

You have dry skin and thinning hair

Dry skin and thinning or dry hair is another sign of an underactive thyroid. Just like any other cells in the body, the growth and metabolism of hair follicles and skin cells are regulated by thyroid hormones. 

A study published in the International Journal of Trichology reported differential levels of thyroid dysfunction in different types of alopecia, and also showed that the prevalence of thyroid dysfunction in alopecia patients increased with age.

Similarly, when skin cells are not replenished frequently enough, dead skin cells don’t shed as they normally would. This accumulation of damaged skin can lead to a flaky, dry appearance.

Close up of dry skin on woman's hand

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You experience heavy or irregular menstrual periods

Changes to the menstrual cycle can happen for many different reasons. While some can be relatively harmless and relate to lifestyle factors like stress, dieting, traveling or changes to body weight, others signify serious health problems. 

Indeed, heavy and/or irregular menstrual periods are one of the signs of an underactive thyroid. That’s because thyroid hormones are linked to the functioning of the reproductive system.

The complex interplay between different hormones helps regulate the menstrual cycle and ensure that ovaries and uterus work properly. According to a review published in the Annals of the New York Academy of Sciences, women with hypothyroidism tend to experience heavier and more irregular periods. 

You struggle with low mood

One of the less apparent signs of an underactive thyroid is depression. It is worth pointing out though that of all the symptoms mentioned so far, this one may be the least clear-cut. 

Scientists are still unsure whether there is a direct link between hypothyroidism and mood disorders. According to a meta-analysis published in JAMA Psychiatry, the link between hypothyroidism and depression is not as strong as previously assumed, and may be more pronounced in females than males. Another meta-analysis published in Translational Psychiatry found that hypothyroidism may be related to mood disorders in younger patients, but not in older ones. It also demonstrated that thyroid hormone replacement therapy does not seem to improve symptoms of depression.    

This article is for informational purposes only and is not meant to offer medical advice.

Anna Gora
Health Writer

Anna Gora is a health writer at Live Science, having previously worked across Coach, Fit&Well, T3, TechRadar and Tom's Guide. She is a certified personal trainer, nutritionist and health coach with nearly 10 years of professional experience. Anna holds a Bachelor's degree in Nutrition from the Warsaw University of Life Sciences, a Master’s degree in Nutrition, Physical Activity & Public Health from the University of Bristol, as well as various health coaching certificates. She is passionate about empowering people to live a healthy lifestyle and promoting the benefits of a plant-based diet.