The thyroid, small, butterfly-shaped, sitting quietly at the front of your neck, quietly runs the show for many of your body’s most important functions. From metabolism to heart rate, blood pressure, temperature regulation, and even how your body reacts to other hormones, this little gland packs a big punch. And when it misbehaves, it can cause a wide range of frustrating, confusing, and sometimes serious symptoms.Dr. Ashok Kumar Jhingan, Senior Director at the Centre for Diabetes, Thyroid, Obesity & Endocrinology at BLK-MAX Super Speciality Hospital, says, “The function of the thyroid gland is to control metabolism. By this process, the body transforms the food we consume into energy.All the cells in the body need energy to function. This hormone plays a key role in regulating blood pressure,body temperature , heart rate, metabolism and the reaction of the body to other hormones. The thyroid gland not only controls metabolic processes , but also the activation response of the body to other hormones.”

Why the thyroid matters

Your thyroid produces hormones called T3 (Triiodothyronine) and T4 (Thyroxine). These hormones are essential for metabolism, which is how your body converts food into energy. Every single cell in your body needs energy, so the thyroid indirectly affects nearly everything, from heartbeats to digestion, from your ability to handle stress to how you respond to other hormones.When the gland doesn’t produce enough hormone, it’s called hypothyroidism. Common signs include fatigue, weight gain, constipation, dry skin, feeling cold, and even depression. Hyperthyroidism happens when your thyroid goes into overdrive, producing too much hormone. This can cause weight loss, rapid heartbeat, anxiety, heat intolerance, excessive sweating, and tremors. Then there are autoimmune thyroid diseases like Hashimoto’s, which usually causes hypothyroidism, and Graves’ disease, which leads to hyperthyroidism.Other thyroid-related problems include goiter (enlarged thyroid), thyroid nodules, inflammation called thyroiditis, and, in rare cases, thyroid cancer.

So, what tests should you consider?

The first test most doctors recommend is TSH (Thyroid Stimulating Hormone). It’s a simple blood test that shows whether your thyroid is being told to produce more or less hormone. A high TSH usually points to hypothyroidism, while a low TSH suggests hyperthyroidism. Timing can matter if you’re on thyroid medication, you usually do the test about 4-5 hours after taking your pill. One tip: avoid biotin supplements (common in hair and nail products) for about a week before the test since they can interfere with results.Your doctor might also check T4 and T3. High levels of T4 often indicate an overactive thyroid. T3 levels are especially useful to detect hyperthyroidism.Thyroid-specific antibodies like TPO antibodies indicate Hashimoto’s thyroiditis, and TRAB (TSI antibodies) are seen in Graves’ disease. Knowing your antibody levels helps your doctor figure out if your thyroid issues are caused by your immune system attacking the gland.Imaging can also help. Ultrasound is used to detect nodules. A thyroid scan using a small amount of radioactive iodine helps check the size, shape, and activity of the thyroid, while FNAC (Fine Needle Aspiration Cytology) can confirm whether a nodule is benign or malignant.

Who should get screened and when

Even if you don’t have symptoms, screening can be valuable. Dr. Jhingan recommends that women of reproductive age, those planning pregnancy, should check baseline TSH, free T4, and TPO antibodies. Screening is also important in the first month of pregnancy to ensure both mother and baby are protected.People taking certain medications like Amiodarone or Lithium should also get regular tests. Those undergoing immunotherapy for cancer should be screened too, as these treatments can affect the thyroid.For older adults, thyroid problems can fly under the radar because symptoms often look like normal aging—fatigue, slower metabolism, or minor changes in weight or mood. Annual screening is usually advised for those over 60.

Red flags that shouldn’t be ignored

Some thyroid symptoms are easy to brush off. Feeling unusually tired, gaining or losing weight unexpectedly, changes in appetite, palpitations, tremors, heat or cold sensitivity, changes in bowel habits, or thinning hair and nails could all point to thyroid problems. Swelling at the base of the neck can also be a sign of goiter or nodules.Dr. Jhingan stresses, “Even if you feel fine, if you fall into any of these risk categories, or notice unusual symptoms, get your thyroid checked. Early detection makes management much simpler.”

Making sense of thyroid numbers

TSH levels usually range from 0.5 to 4.5 mIU/L, but doctors adjust these ranges depending on age and other factors. For instance, a TSH of 7 in a 65-year-old might be perfectly normal. High TSH means your thyroid isn’t making enough hormones, and low TSH suggests it’s overactive. T4 and T3 levels help confirm the picture.

Bottom line

Your thyroid may be small, but it has a huge impact on how you feel every day. Whether you’re young, planning a family, on medications, or simply noticing changes in your body, a thyroid check can give you peace of mind, and keep your metabolism, heart, and energy on track.Medical experts consulted This article includes expert inputs shared with TOI Health by:Dr. Ashok Kumar Jhingan, Senior Director at the Centre for Diabetes, Thyroid, Obesity & Endocrinology at BLK-MAX Super Speciality HospitalInputs were used to explain when one should take thyroid tests and what do the numbers mean.