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Introduction

In the U.S., the most common cause of hypothyroidism – an underactive and slower-than-normal thyroid – is Hashimoto's thyroiditis, an autoimmune disease. Having Hashimoto’s or hypothyroidism increases your risk of hearing loss. Unfortunately, this important connection is frequently overlooked by both health care providers and thyroid patients. Ahead, a look at hearing loss, and the relationship with Hashimoto’s and hypothyroidism.

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The ear is a highly sophisticated sensory organ that transmits sound to your brain and helps to maintain your balance. There are three parts to your ear: the outer (or external) ear, the middle ear, and the inner ear.

The outer ear is the actual physical ear. And that extends into the ear canal all the way up to your eardrum where sounds transmit through your ear canal to your eardrum (also known as the tympanic membrane). The ear canal contains earwax, which helps collect dust and debris and prevent it from reaching the eardrum. The eardrum itself is highly sensitive to pressure changes from sound waves, which cause it to vibrate.

The function of the middle ear is to amplify the sound waves before they enter the inner ear. The middle ear contains three small bones – the hammer (malleus), anvil (incus), and stirrup (stapes). It also has the oval window – a membrane that covers the entrance to the inner ear. When your eardrum vibrates, the bones in the middle ear further transmit the sound waves to the oval window. Finally, the eustachian tube helps equalize pressure between the eardrum and the oval window.

The maze-like inner ear is called the labyrinth. The labyrinth contains the cochlea, the auditory nerve, and the vestibular apparatus. The cochlea looks like a snail shell and contains fluid that moves microscopic hairs. The auditory nerve carries information from the cochlea to the brain. The vestibular apparatus is a 3-ringed passage with fluid that helps detect movements in our body.

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In our Paloma Speaker Series event on hearing loss, audiologist Dr. Katie Keese explained the three different types of hearing loss: sensorineural hearing loss, conductive hearing loss, and mixed hearing loss.

“Sensorineural hearing loss makes up 90% of all problems, making it the most common type of hearing loss. Conductive hearing loss deals with the outer and the middle portion of the ear. That type of hearing loss can be anything from a blockage from ear wax, an injury, or allergies and fluid behind the middle ear. And then there's mixed hearing loss, a combination of the two.”

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The signs and symptoms of hearing loss can be subtle, and develop over time. Some of the most common symptoms and signs include:

• Ringing in the ear (known as tinnitus)
• A sensation of fullness or pressure in the ears
• Noticing that you need to turn up the volume on devices to better hear and understand speech
• Difficulty understanding people when there’s significant background noise

Says Dr. Keese, “A very common complaint is ‘I hear people, but don't understand what they're saying.’  Or, one on one you're doing okay, but throw in some background noise and it's really hard to distinguish what someone is saying. Some people notice they are turning the TV up – and up and up -- but even when it’s louder, it doesn't make it more clear. You also might have ringing in the ears.”

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Hearing loss is one of the frequently overlooked symptoms of hypothyroidism and Hashimoto’s. The most common types of hearing loss in seen in patients with an underactive thyroid and Hashimoto’s include:

• Sensorineural hearing loss – as with the general population, sensorineural type hearing loss makes up about 90% of the hearing issues seen in people with a thyroid dysfunction, including Hashimoto’s and hypothyroidism.
• Conductive hearing loss – commonly due to obstructions like excessive earwax, a problem that appears to be more common in people with hypothyroidism.
• Autoimmune inner ear disease, also known as AIED, which is more common in people with Hashimoto’s and other autoimmune conditions.

One specific hearing-related symptom frequently reported by thyroid patients is tinnitus – a constant or intermittent ringing or buzzing in the ears.

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Hearing loss is much more common in people with hypothyroidism compared to the general population. Some estimates suggest that at least 25% of people with acquired hypothyroidism have mild to moderate sensorineural hearing loss.

Hypothyroidism also increases the risk of a condition known as sudden sensorineural hearing loss (SSNHL), especially after the age of 50. SSNHL is characterized by rapid onset of hearing loss, either immediately, or over a period of up to three days.

The risk of hearing loss is much higher in people born with a condition known as congenital hypothyroidism, who face a three times higher risk of hearing loss compared to the general population. Overall, around 20% of people with congenital hypothyroidism have mild hearing loss, and it’s estimated that some 17% require hearing support by adulthood.

Autoimmune Hashimoto’s thyroiditis is linked to an increased risk of autoimmune inner ear disease. AIED is a condition in which autoimmune antibodies attack the inner ear, causing ringing in the ears, and increasing or sudden hearing loss. Some studies have found that people may have both Hashimoto's and AIED.  

Hashimoto’s is also linked to an increased risk of another autoimmune condition called Meniere's disease, which is an autoimmune inner ear disease that can cause hearing loss.

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If your hearing loss is caused by undiagnosed or insufficiently poorly treated hypothyroidism, we have some good news. Studies have shown that getting optimal treatment for hypothyroidism for a period of six to twelve months can improve hearing in around half of all patients with hypothyroidism. And, even better, around 15 percent of patients have complete resolution of their hearing loss!

What is “optimal thyroid treatment? If you have Hashimoto's, that means Thyroid Stimulating Hormone (TSH), Free Thyroxine (Free T4) and Free Triiodothyronine (Free T3 levels) that are in the optimal and not just normal range. It also includes dietary, lifestyle, and medical management of your thyroid autoimmunity, to reduce Thyroid Peroxidase (TPO) Antibody levels, and calm your overall autoimmune inflammation.

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At first, you may not notice subtle changes in your hearing. A good starting point is to periodically take an online test to assess whether you have any degree of hearing loss. You'll need headphones or earbuds, and this simple test takes just a few minutes. The results can help you determine if you might benefit from a checkup with a hearing healthcare professional. A reputable online test is located online at HealthyHearing.com.

‍Many experts also recommend that everyone diagnosed with hypothyroidism have a baseline hearing evaluation at the time of diagnosis. This gives you an assessment of your hearing that can be used as a point of comparison later. They also recommend that you have a hearing evaluation annually.

If you notice some gradual hearing loss or other hearing-related symptoms, your best course of action is to see an ear, nose and throat (ENT) doctor. The ENT can evaluate hearing loss that results from factors unrelated to your thyroid. Some causes of hearing loss include:

• Inner ear damage (as seen with aging and chronic exposure to loud noises)
• Infection
• Abnormal bone growths or tumors
• Ruptured eardrum
• Ear wax build-up or a foreign body in the external canal

According to Dr. Keese, in many cases, “When we're looking at conductive hearing loss, there's something going on in the outer or the middle ear. A lot of times that can be medically managed. Your hearing organ is working great, but something in the outer or the middle ear is making it worse at the moment. If it's ear wax, we can remove it. If it's a foreign object, we can remove it. If there's fluid behind the eardrum, they can put in PE tubes, which are pressure equalization tubes. A physician, ideally, an ear nose and throat physician who could perform whatever medical management needed.”

Finally, if you have sudden, new, or acute hearing loss? Dr. Keese confirms the recommendations of all hearing professionals: go to an ear, nose and throat (ENT) doctor immediately! Says Dr. Keese: “If anyone ever says that they had a sudden hearing loss, where you wake up one day and your hearing is gone, that is a huge red flag. Call your closest ENT physician and say the word ‘sudden hearing loss.’ And you will skip any sort of waiting period, because you have a short window of time for treatment. The sooner you can get in to see an ENT, the sooner they can start treatments.”

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During out Paloma Speaker Series presentation on hearing loss, Dr. Katie Keese described what happens during a baseline or followup hearing evaluation.

“First, the audiologist will gather your medical history – and be sure to let them know about your thyroid condition.

They will look in your ears and check for any sort of blockages.

They'll also do something called a tympanogram. It's a tiny probe that they put in your ear. It creates a seal and it blows some air in your ear. And it kind of feels like you're going up and down in an airplane. And what that's doing is that's checking to see how the bones in the middle ear are working, and if your eardrum is moving the way it should.

Then they'll do the beep test that everyone is familiar with. They do the test with headphones that sit on the ear, or they might use little foam tips that they put in the ear. And we plot the information on what’s called an audiogram, a graph. They want to find out what’s the softest sound that you can hear. We call that your threshold.

Then they'll do a bone conduction test. Instead of headphones, it's a little headband with an oscillator. If you just take your finger and feel right behind your ear, that's your bone right there. And we set it on the bone and it actually skips the outer and middle ear and is just testing how your inner ear is working.

Then we go on to test your speech understanding. Sometimes we might do speech and noise testing to see how you're doing in noise.

It’s the least painful thing you can do for your overall health, and not a scary appointment at all. The whole evaluation can take maybe about 30 minutes max.”

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For hypothyroid patients, reducing or eliminating symptoms – including hearing impairment – starts with optimizing your thyroid function. The Paloma home thyroid test kit makes thyroid testing easy. You can also schedule a virtual visit with one of Paloma’s knowledgeable thyroid practitioners, who can work with you to ensure that you are getting the best possible thyroid treatment.

And one final thing to keep in mind: some hearing loss can be prevented! According to Dr. Keese, “Hearing protection is the biggest thing that you can do to prevent noise-induced hearing loss. I like loud concerts, for example, but the ringing in your ears after a concert is actually called a temporary threshold shift, a TRT, and it damages your hearing and the hair cells a little bit. Basically, every time you damage the hair cells, they come back, but not as strong as they were before. So, the best thing that you can do to prevent hearing loss is try and protect it as much as possible.”

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