Subclinical hypothyroidism affects millions of people in the United States. Its symptoms can go unnoticed, and the long-term risks should not be ignored.
Read below to learn what subclinical hypothyroidism is, its symptoms, its root causes, and a thyroid-boosting diet plan.
What is subclinical hypothyroidism?
Subclinical hypothyroidism exhibits mild hypothyroidism symptoms. With subclinical hypothyroidism, your thyroid-stimulating hormone (TSH) levels are elevated, but your T3/T4 levels are normal.
An estimated 5% of Americans exhibit signs of this precursor to thyroid disease. More than a quarter of those with subclinical hypothyroidism (also called subclinical thyroid disease) could develop into hypothyroidism patients within six years of initial diagnosis.
“Subclinical” refers to a stage before full-blown hypothyroidism — and, for some, these symptoms may never progress to hypothyroidism. The thyroid hormones produced and secreted by your thyroid will still fall within normal reference ranges.
What is the difference between subclinical hypothyroidism and hypothyroidism? Hypothyroidism is characterized by an underactive thyroid gland — high TSH, low T3/T4. In subclinical hypothyroidism, a patient has only high TSH.
Is subclinical hypothyroidism serious? Typically, subclinical hypothyroidism is not serious per se. Sometimes it is a temporary result of inflammation. Even if it is not temporary, subclinical hypothyroidism is usually not life-threatening.
If you are pregnant, however, you most certainly want to treat subclinical hypothyroidism as soon as possible. TSH (also known as thyrotropin) levels outside the normal range increase risk of miscarriage.
Some studies claim your risk of cardiovascular disease goes up with TSH levels, but research on the cardiovascular risk is inconclusive overall.
Causes of Subclinical Hypothyroidism
Subclinical hypothyroidism has several potential root causes separate from hypothyroidism.
The most common root cause of subclinical hypothyroidism is inflammation. This inflammation can be caused by:
- Acute infection, particularly one that requires hospitalization
- Cardiovascular disease
- Elevated insulin and other cardiometabolic issues
- Dietary issues/food sensitivities
- Hormone imbalances or taking birth control pills
Another common cause of subclinical hypothyroidism is stress. Mental stress can kick your pituitary gland into high gear.
Subclinical hypothyroidism may eventually become full-blown hypothyroidism in some cases, so it’s important to work with your healthcare provider to address it as needed.
Unlike full hypothyroidism, 90% of which are autoimmune-related (Hashimoto’s disease), subclinical hypothyroidism is often not related to autoimmunity issues.
Risk Factors of Subclinical Hypothyroidism
Who is at risk of subclinical hypothyroidism?
According to 2019 research, serum thyrotropin rises as you get older, meaning prevalence of subclinical hypothyroidism increases with age.
Females are two to five times more likely to show signs of subclinical hypothyroidism than males.
Family history of Hashimoto’s disease can increase your risk of Hashimoto’s and therefore subclinical hypothyroidism.
If you take medications containing iodine or lithium, you may find yourself at a higher risk of subclinical hypothyroidism.
During a hospital stay, the risk for subclinical hypothyroidism rises.
Symptoms of Hypothyroidism at the Subclinical Level
When TSH levels are only mildly elevated, subclinical hypothyroidism can have no perceivable symptoms.
However, when mild hypothyroid symptoms do appear, you can expect the following:
- Chronic fatigue
- Hair loss
- Unexplained weight gain
- Sensitivity to the cold
- Impaired cognitive function, memory issues
A study published in Archives of Internal Medicine shows that a TSH level of 7.0 mIU/L or greater (within the subclinical range) can lead to congestive heart failure, compared to euthyroid subjects. (Euthyroid means you have a healthy thyroid.) Other studies claim elevated TSH values can lead to heart disease.
Diagnosis & Treatment Plan
As far as diagnosis, we begin with an hsCRP (high sensitivity inflammation blood test). Then, we check if inflammation is occurring in antithyroid antibodies (like anti-thyroid peroxidase) in order to spot inflammation happening at the thyroid itself. Quality of life is also assessed.
Taking biotin supplements can artificially decrease thyrotropin levels. This is why you should stop taking any biotin seven days before thyroid blood work.
Medication is not often used at the subclinical stage because we want to check everything else first, such as nutrient levels, other hormone levels, estrogen dominance, and status of your thyroxine-binding globulin.
Levothyroxine and naltrexone are two medications prescribed at this stage. However, pharmaceuticals are often the last treatment option we suggest (unless pregnancy demands a quicker timeline).
Pregnant women are a different case. To protect fetal growth, we want to ensure your TSH levels do not climb too high.
What TSH level is considered subclinical hypothyroidism?
Normal range for TSH levels are measured by thyroid function tests between 0.4 and 4.0 milliunits per liter (mIU/L). Subclinical hypothyroidism is often defined by TSH levels in the range of 4.6 to 10.0 mIU/L.
Elderly patients (70 years and older) may have a reference range of TSH levels in the 5.0 to 6.0 mIU/L range. They do not need as fast a metabolism and are more susceptible to the risks of over-replacement.
The ideal reference range for a pregnant woman is between 0.5 and 2.5 mIU/L. Outside of that range, the risk of miscarriage increases. Many women who take thyroid medication need to increase their dosage when they become pregnant.
Do you treat subclinical hypothyroidism?
Treatment of subclinical hypothyroidism is simple but sometimes controversial. We will identify if your subclinical hypothyroidism is temporary. If not, we will walk you through the management of subclinical hypothyroidism.
If you are pregnant, even subclinical hypothyroidism needs to be addressed, so you can avoid a miscarriage. Pregnant women with subclinical hypothyroidism should remain closely monitored in follow-up sessions by an OB/GYN.
Natural hypothyroidism treatments may not always be the right choice for pregnant patients (described more in detail below when talk about risks of treatment).
It is uncommon to treat subclinical hypothyroidism during a hospital visit because temporarily high TSH values are so common when you are hospitalized.
Foods to Eat and Avoid for Healthy Thyroid Function
For otherwise healthy adults, following the Autoimmune Paleo (AIP) Diet for 3-6 months offers great success in naturally treating thyroid dysfunction, especially when the cause is Hashimoto’s Thyroiditis. (This is not recommended for pregnant women.)
Foods to Eat:
- Clean protein (especially fatty fish, rich in omega-3 fatty acids)
- Kombucha, kimchi, and other probiotic-containing foods
- Non-nightshade vegetables
- Cruciferous vegetables (like kale and brussels sprouts, and steamed)
- Green tea
- Garlic, turmeric
- Gelatin, bone broth
Foods To Avoid:
- All nightshade vegetables
- Nuts, seeds
- Dried fruits
- Vegetable oil, canola oil
- Beans/legumes (because of the potential allergen lectin)
- Sugar, alternative sweeteners
- Processed foods
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Natural Remedies for Underactive Thyroid
There are a few actions you can take to naturally remedy an underactive thyroid.
Stress relief can be important to treating subclinical hypothyroidism.
Relieving stress can be as easy as getting a good night’s rest, avoiding blue light exposure before bed, meditating, and breathing in fresh outside air. To receive 10% off of our favorite blue light blocking glasses by Ra Optics, enter code “PRIMEHEALTH” at checkout.
We sometimes suggest dietary supplements as a treatment option for an underactive thyroid:
- Vitamin D – for medical grade, 3rd-party tested Vitamin D see our online store.
- Zinc – for medical grade, 3rd-party tested Zinc, see our Prime Zinc
Always consult a healthcare professional before starting a new dietary supplement.
Risks of Treating Subclinical Hypothyroidism
It doesn’t seem fair, but most risks associated with treating subclinical hypothyroidism come with being pregnant.
Although it is necessary to treat subclinical hypothyroidism in pregnant women, treatment can increase their risk of gestational hypertension.
Pregnant women should not adhere to the AIP Diet as with most healthy adults with an underactive thyroid. For example, pregnant women need choline found in egg yolks — which is forbidden on a strict AIP Diet.
Many of the dietary supplements we suggest are most likely safe in pregnant women, but have not been tested for safety during pregnancy.
Finally, geriatric patients should be diagnosed and treated differently than younger healthy adults. In patients over 70 years of age, a higher TSH concentration is not only expected, it may even be preferred. Treatment risks triggering over-replacement or even thyroid failure.
Looking to the Future
Whether your subclinical hypothyroidism is early full-on hypothyroidism or a more temporary condition, it can be critical to address as soon as you can.
With conflicting scientific studies in recent years, we at PrimeHealth use our personal experiences with local Colorado patient successes to determine an individualized treatment plan for you. If you are concerned about subclinical hypothyroidism, make an appointment and put your mind at ease.
If interested in working one-on-one with the PrimeHealth team, please schedule your free phone consultation using this link.
- Subclinical hypothyroidism is characterized by higher than normal serum TSH (thyroid-stimulating hormone) levels while thyroid hormone levels (like free thyroxine, also known as free T4) remain normal.
- Subclinical hypothyroidism can be caused by inflammation, stress, or even birth control.
- Older adults and females are at higher risk of subclinical hypothyroidism.
- Symptoms include fatigue, weight gain, memory problems, and potentially cardiovascular events.
- The AIP Diet is recommended for many subclinical hypothyroidism patients for several reasons, though not recommended if you are pregnant.
- Dietary supplements and stress relief should help to balance thyroid function.
- If you are pregnant or over the age of 70, there are risks in treating subclinical hypothyroidism that you need to discuss with primary care physicians.
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