When your thyroid works properly, you never know it’s there. But when it malfunctions, it wreaks havoc on your body.

Your thyroid is a flat, butterfly-shaped gland located directly underneath your Adam’s apple. Everything from brain development, bone strength, heart function, digestion and muscle control are affected by the thyroid. Even so, it is not always easy to tell when your thyroid is not working correctly.

Here are 5 surprising signs that could signal a problem with your thyroid gland.

1. Depression

When your thyroid underperforms, your metabolism slows and makes you tired, less focused and depressed. Called hypothyroidism, the disorder decreases the amount of serotonin that your brain produces, which intensifies feelings of anxiousness and sadness. You might even find that it’s hard to get up in the morning.

How can you tell if you are depressed or if your thyroid isn’t working properly? If you are on antidepressants but don’t feel any better, ask your doctor to check for a thyroid disorder.

2. Hair loss

When metabolism slows, your body kicks into overdrive to protect vital functions. Keeping your hair is not one of them. Severe hair loss or brittle, coarse and dry hair that breaks easily are symptoms of a thyroid problem.

3. Carpal Tunnel

Those aching joints and muscles — even plantar fasciitis in the feet and weakness in the arms — can be clues of undiagnosed thyroid issues. Swelling signals inflammatory issues, which could also be caused by your thyroid.

4. Sensitivity to cold

It makes sense: hypothyroidism causes the body to be sluggish, and a sluggish body is slow to produce energy and warmth. Frequently being cold is a symptom that you should mention to your doctor.

5. Infertility

Anything that upsets the natural rhythm of the menstrual cycle complicates pregnancy. This includes thyroid disorders. Because the thyroid produces hormones, there are a host of reproductive health problems associated with an imbalance in the thyroid: decreased sex drive, miscarriages, and in some cases, infertility. Thyroid screening should be included in tests for women who have irregular periods or are struggling to get pregnant.

Concerned that you might be suffering from a thyroid problem? A simple blood test can dispel your fear.

Visit one of the world-renowned specialists in the USC Tina and Rick Caruso Department of Otolaryngology – Head and Neck Surgery at Keck Medicine of USC. If you are in the Los Angeles area, make an appointment by calling (800) USC-CARE (800-872-2273) or visiting https://www.keckmedicine.org/request-an-appointment/.

By Heidi Tyline King