Why thyroid trouble is so often missed—and how to spot the signs
Millions of Americans have thyroid disorders, but up to 60 percent don’t know it. From subtle tremors to creeping brain fog, here’s what doctors say you shouldn’t ignore.
Tucked at the base of the neck, the thyroid gland quietly influences nearly every system you depend on—from your heartbeat and digestion to bone strength and brain function.
Despite its central role, many people don’t realize when thyroid issues arise. “Symptoms can easily sneak into your everyday life and get brushed off as stress, aging, or just being busy,” says Jodi Fox Mellul, an endocrinologist at Inspira Health in New Jersey. Early signs may be as subtle as difficulty sleeping through the night, unexplained anxiety or irritability, or a slight tremor in your hands when holding a cup of coffee.
Paying attention to such clues matters, as research shows that untreated thyroid issues can lead to serious heart conditions, brittle bones, fertility challenges, and even brain disorders—complications endocrinologists hope to prevent through expanded screening and wider education.
“The importance of broader screening and more public awareness surrounding thyroid disorders cannot be overstated, especially given their high prevalence and the significant impact they can have on quality of life and long-term health,” says Ravali Veeramachaneni, an obesity medicine physician and endocrinologist at Cleveland Clinic in Ohio.
What the thyroid is—and why its imbalances can be felt everywhere
Shaped like a butterfly and no larger than two thumbs pressed together, the thyroid sits just below the Adam’s apple. It produces hormones such as thyroxine (T4), triiodothyronine (T3), and calcitonin—chemical messengers that regulate how nearly every cell in your body uses energy. In fact, these hormones influence metabolism, body temperature, heart rate, brain function, digestion, muscle strength, and more.
“The thyroid makes, stores, and releases these hormones, so it is of vital importance,” explains Marilyn Tan, an endocrinologist and internal medicine physician at Stanford Health Care. What's more, “thyroid hormones regulate the rate at which each cell uses oxygen and converts substrates into energy,” adds Veeramachaneni. "So any imbalance will have ripple effects across virtually all body systems and organs.”
She suggests thinking of thyroid hormones “as the throttle for the body’s engine.” In hyperthyroidism, “the engine is running too fast” by producing too many hormones, she explains. In hypothyroidism, the engine is running too slow and producing too few. At either end, symptoms like moodiness, insomnia, fatigue, muscle weakness, weight fluctuations, hot or cold intolerance, and heart palpitations can occur.
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Thyroid issues can also be autoimmune in nature, as with Hashimoto’s disease and Graves’ disease—where the immune system mistakenly attacks the thyroid gland.
Regardless of type, “thyroid dysfunction can affect your quality of life, your ability to think, keep up with work or parenting, or enjoy things you used to love,” says Mellul.
Over time, dysfunction can also strain the heart and accelerate bone loss, says Tan, increasing the risk of heart disease, fractures, and osteoporosis—especially in older adults.
Thyroid’s surprising role in cognitive decline
Research has also linked thyroid disorders to an increased risk of dementia—particularly vascular dementia. A 2024 meta-analysis similarly found that both overt and milder “subclinical” forms of hyperthyroidism are associated with Alzheimer's risk. “Even subtle thyroid changes,” Veeramachaneni adds, “can quietly erode memory and concentration years before a dementia diagnosis is made.”
Possible explanations for these effects include high thyroid hormone levels damaging brain blood vessels, impairing synaptic connections, and increasing oxidative stress. Long-term hormone excess may also alter neurotransmitters or promote amyloid-beta buildup—a protein linked to Alzheimer’s disease. “Researchers are still investigating all mechanisms,” says Veeramachaneni, “but the association is concerning—especially for older adults, who may not have obvious symptoms yet still face irreversible complications if the condition is missed.”
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This all matters because thyroid dysfunction is far from rare. In the U.S., some 20 million Americans live with some form of thyroid disorder; and more than one in 10 people will develop a thyroid condition during their lifetime. Research shows that when milder cases are counted, the numbers are even higher—particularly among adolescents and elderly adults. In fact, one study found that up to one in four Americans 65 and older may have some level of thyroid dysfunction.
Despite such high numbers, awareness lags. Up to 60 percent of people with a thyroid disorder don’t know they have it, notes the American Thyroid Association. This is largely because thyroid symptoms are “diverse and non-specific, and often mimic other conditions like stress, depression, aging, or general fatigue,” explains Veeramachaneni.
Complicating matters further, "some patients are tremendously affected, while others are surprisingly symptom-free," adds Giuseppe Barbesino, an endocrinologist at Massachusetts General Hospital.
The power of early detection
The good news is that hyperthyroidism and hypothyroidism are highly treatable once identified—and treatment can be life-changing. “As a physician, it can be very rewarding to see a young woman who has been miserable for months with unexplained, disconcerting symptoms return to her usual self within a few weeks of effective treatment,” says Barbesino.
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Prompt diagnosis can protect heart rhythm, preserve bone density, stabilize mood, improve sleep, and guard against cognitive decline. Research shows that early treatment may even improve or reverse eye changes in Graves’ disease before they cause permanent damage.
Conversely, failing to identify thyroid dysfunction can mean irreversible harm. “It can be frustrating to see an elderly man with permanent atrial fibrillation, which could have been prevented had his mild hyperthyroidism been detected earlier,” says Barbesino.
Early detection is supported through public awareness of thyroid disorders and associated symptoms and more frequent screening. The American Thyroid Association recommends screening for thyroid dysfunction starting at age 35 and repeating every five years thereafter. Screening could help “the millions of people who have a thyroid condition and don’t even know it,” says Mellul.
What to watch out for and how diagnoses occur
Because thyroid disorders so often masquerade as other conditions, spotting patterns is key. Signs may appear scattered at first—persistent anxiety or irritability, an unshakable restlessness, or weight slipping off despite a steady appetite. Others pick up on subtler signs: hand tremors, frequent urination, excessive sweating, swelling at the base of the neck, or eye changes like puffiness, bulging, or blurred vision. Women may also experience irregular cycles or fertility issues.
“Most thyroid problems can be detected with a simple blood test,” says Mellul. Your provider may also recommend imaging to get a closer look at the gland. “If testing shows your thyroid hormones are in the normal range, then further investigation should be done to determine what else could be contributing to your symptoms,” says Tan.
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Once diagnosed, treatment depends on the cause and severity of the dysfunction but often involves medication, radioiodine therapy, or surgery.
None of that can happen, however, “until you discuss your symptoms and concerns with your healthcare provider so that appropriate screening and testing can be conducted,” stresses Tan.
“Don’t ignore your gut if something feels off,” adds Veeramachaneni. “A simple conversation and test can give you answers and be instrumental in protecting your long-term health.”
