The American Thyroid Association recommends that all adults get their first thyroid screening at age 35, then repeat it every five years. But several situations call for testing much sooner: unexplained symptoms, pregnancy, a family history of thyroid disease, or having another autoimmune condition. Here’s how to know if it’s time for you.
Routine Screening by Age
Even without symptoms, thyroid problems become more common as you get older. The American Thyroid Association’s baseline recommendation is a blood test starting at 35, repeated every five years. The American Academy of Family Physicians goes further for older adults, recommending screening for everyone over 60 regardless of gender. That emphasis on older adults reflects real numbers: the Framingham study found that 4.4% of people over 60 had clear thyroid deficiency.
The U.S. Preventive Services Task Force, which sets screening guidelines for many conditions, currently says there isn’t enough evidence to recommend for or against screening in nonpregnant adults who have no symptoms. That doesn’t mean screening is harmful. It means the task force hasn’t found enough data to make a universal call. In practice, many doctors still follow the ATA’s age 35 recommendation, especially if you have risk factors.
Symptoms That Should Prompt Testing
Your thyroid controls your metabolism, heart rate, and body temperature, so dysfunction tends to show up in ways that affect your whole body. The tricky part is that many thyroid symptoms overlap with stress, aging, or other conditions. A blood test is the only way to confirm what’s going on.
An underactive thyroid (hypothyroidism) typically causes fatigue and sluggishness, constipation, hair thinning or loss, dry skin, puffiness or swelling in the face or legs, feeling cold when others are comfortable, and unexplained weight gain. An overactive thyroid (hyperthyroidism) tends to produce the opposite pattern: anxiety, tremors, insomnia, a racing or irregular heartbeat, heat intolerance, and weight loss despite eating more than usual.
Some symptoms deserve faster attention. An irregular heartbeat, whether too fast, too slow, or skipping beats, warrants a prompt call to your doctor. Menstrual irregularities, including very heavy flow, cycles that come too frequently or too far apart, or difficulty conceiving, are also worth investigating. Neck pain or swelling after a viral illness, combined with tremors, heart palpitations, or feeling wired but exhausted, can signal a temporary but treatable thyroid inflammation.
Physical Changes in Your Neck
A visible or palpable lump in the front of your neck, just below the Adam’s apple, is one of the most straightforward signs that your thyroid needs evaluation. This swelling, called a goiter, can develop gradually enough that you don’t notice it yourself. Other people may spot it first.
Beyond the visible lump, pay attention to a feeling of tightness in your throat, hoarseness that doesn’t resolve, neck vein swelling, or dizziness when you raise your arms above your head. If the swelling progresses, it can compress your windpipe and esophagus, making it harder to breathe or swallow. Any lump in the front of your neck is worth getting checked, even if it isn’t causing discomfort yet.
If You’re Planning a Pregnancy or Currently Pregnant
Thyroid health has an outsized impact on fertility and fetal development, so the testing timeline around pregnancy is more aggressive than general screening.
If you’re struggling to conceive, thyroid testing should be part of the workup. Current guidelines recommend checking levels in all women seeking treatment for infertility. For women undergoing IVF or similar assisted reproduction, treatment is recommended if levels are even mildly off, with a target that’s tighter than the general population range. Women already on thyroid medication who are planning a pregnancy should have their levels checked with a goal of keeping them in the lower end of normal before conception.
Once you’re pregnant or even suspect you might be, testing should happen right away. Guidelines recommend a blood test as soon as pregnancy is confirmed, then every four weeks through mid-pregnancy (when thyroid function tends to stabilize), and at least once more around 30 weeks. If you’re already taking thyroid medication when you find out you’re pregnant, contact your provider immediately. The standard recommendation is to increase your dose right away, typically by adding two extra doses per week on top of your current daily amount, because your body’s demand for thyroid hormone rises quickly in early pregnancy.
Higher-Risk Groups
Certain conditions make thyroid dysfunction significantly more likely. If you have any autoimmune disease, your risk of developing a thyroid problem is elevated. The conditions most strongly linked include type 1 diabetes, celiac disease, pernicious anemia, lupus, rheumatoid arthritis, Sjögren’s syndrome, and Addison’s disease. If you’ve been diagnosed with any of these, periodic thyroid testing makes sense even if you feel fine.
A family history of thyroid disease, a personal history of radiation to the head or neck, or a previous thyroid problem that resolved also puts you in a higher-risk category. Women are affected far more often than men. Population studies have estimated that overt hypothyroidism affects about 2% of women over 70 but only about 0.1% of men over 60.
What the Blood Test Actually Measures
The standard screening test measures TSH, a hormone produced by your pituitary gland that tells your thyroid how hard to work. It’s the single most sensitive marker for thyroid dysfunction. When your thyroid is underactive, TSH rises because your brain is trying to push the gland harder. When your thyroid is overactive, TSH drops because the brain is pulling back.
Most labs flag a TSH above 10 as clearly elevated and a TSH below 0.1 as clearly suppressed. The gray zone in between, sometimes called subclinical thyroid disease, is where things get murkier. If your TSH is mildly off, your doctor may order a follow-up test for free T4 (the active thyroid hormone) to get a fuller picture.
In some cases, your doctor may also test for thyroid antibodies. These are most useful when there’s diagnostic uncertainty, for example, if your TSH is only marginally elevated and it’s unclear whether you have a real problem or a temporary blip. A positive antibody result points toward autoimmune thyroid disease (the most common cause of thyroid dysfunction) and, in people with borderline levels, signals a higher risk of progressing to full-blown hypothyroidism over time.
Follow-Up Testing After Starting Treatment
If you’re prescribed thyroid medication, the testing schedule shifts. Because the medication takes about a week to reach half its steady-state level in your blood, doctors typically recheck your levels six weeks after starting or changing a dose. That six-week window gives the medication enough time to stabilize so the blood test reflects your true new baseline.
Once your levels are where they should be, expect a confirmation test in three to six months, then annual checks from that point forward. Life changes like significant weight gain or loss, pregnancy, starting new medications, or aging can all shift your thyroid needs, so those annual tests aren’t just a formality. They catch drift before symptoms return.