The thyroid is a small gland in the neck that sets the pace of your metabolism. When it runs slow or fast, almost every system in the body is affected, which is why the symptoms are so varied and so easily attributed to something else.
Women are affected several times more often than men, and rates in urban India are high.
Underactive Thyroid: The Common One
Hypothyroidism is far more common, and its symptoms accumulate so gradually that people adjust to them.
- Fatigue and sleeping more without feeling rested
- Weight gain despite unchanged eating
- Feeling cold when others are comfortable
- Dry skin and coarse, thinning hair
- Constipation
- Heavy or irregular periods
- Low mood, poor concentration and memory difficulty
- Muscle aches and cramps
- Puffiness around the eyes
- Hoarse voice
The most common cause in India is Hashimoto thyroiditis, an autoimmune condition in which the immune system gradually damages the gland. Iodine deficiency remains a cause in some regions despite salt iodisation.
Overactive Thyroid: The Opposite Picture
Hyperthyroidism accelerates everything, and it is often mistaken for anxiety.
- Weight loss despite a good or increased appetite
- Palpitations and a fast resting pulse
- Heat intolerance and excessive sweating
- Tremor of the hands
- Anxiety, irritability and difficulty sleeping
- Frequent loose motions
- Lighter or absent periods
- Muscle weakness, particularly climbing stairs
- Eye changes including prominence or gritty discomfort, in Graves disease
A young woman treated for anxiety who is also losing weight and has a resting pulse of 110 deserves a thyroid test before anything else.
Understanding TSH and the Other Numbers
TSH is the pituitary hormone that instructs the thyroid, and it moves in the opposite direction to thyroid activity, which confuses many patients.
- High TSH: the pituitary is shouting at an underactive gland, so it indicates hypothyroidism
- Low TSH: the pituitary has gone quiet because there is already too much thyroid hormone, indicating hyperthyroidism
- Free T4 and Free T3: the actual circulating hormones, measured alongside TSH
- Anti TPO antibodies: confirm an autoimmune cause and predict progression
Subclinical hypothyroidism means a raised TSH with normal T4. Whether to treat it depends on how high the TSH is, whether antibodies are present, whether you have symptoms, and crucially whether you are pregnant or planning to be.
Thyroid and Pregnancy
This is the situation where thyroid function matters most and where thresholds are strictest.
In the first trimester the fetus cannot make its own thyroid hormone and depends entirely on the mother's supply for brain development. Untreated hypothyroidism in early pregnancy is associated with miscarriage, preterm birth and impaired neurodevelopment.
Targets are tighter in pregnancy than outside it, and women already on treatment usually need their dose increased by around a quarter to a third as soon as pregnancy is confirmed. Do not wait for the next scheduled appointment. Contact your doctor when the test is positive.
Thyroid function is checked at the first antenatal visit as part of routine booking bloods.
Thyroid and Fertility
Both underactive and overactive thyroid disrupt ovulation and can cause irregular cycles, and both are associated with difficulty conceiving and with recurrent miscarriage.
Thyroid testing is a standard part of a fertility assessment for exactly this reason. Correcting an abnormal thyroid is one of the simplest fertility interventions there is, and it is sometimes all that is required.
Taking Thyroid Medication Correctly
Levothyroxine is effective and safe, but absorption is easily disrupted, and inconsistent taking is the usual reason a dose seems not to work.
- Take it on an empty stomach, first thing, with water
- Wait thirty to sixty minutes before eating or drinking tea or coffee
- Separate it by at least four hours from calcium and iron supplements, and from antacids
- Take it at the same time every day
- Do not switch brands casually, since preparations differ slightly
Recheck TSH six to eight weeks after starting or changing a dose, then every six to twelve months once stable. Testing earlier than six weeks gives a misleading result, because levels have not yet reached steady state.
Thyroid Nodules and When to Worry
Nodules are common, particularly in women, and are increasingly found incidentally on scans done for other reasons. The overwhelming majority are benign.
Assessment involves thyroid function tests and an ultrasound, which describes features suggesting whether a nodule needs sampling. A fine needle aspiration biopsy is done for nodules with suspicious features or above a certain size.
Features that warrant prompt assessment include rapid growth, a hard fixed lump, hoarseness of voice, difficulty swallowing or breathing, and a nodule in someone with previous neck radiation or a family history of thyroid cancer.
Who Should Be Tested
Universal screening of every adult is not recommended, but testing is appropriate in these groups.
- Symptoms suggesting over or underactivity
- Planning pregnancy, or newly pregnant
- Difficulty conceiving, or recurrent miscarriage
- A goitre or a palpable nodule
- Unexplained high cholesterol or anaemia
- A family history of thyroid disease
- Another autoimmune condition such as type 1 diabetes or coeliac disease
- New atrial fibrillation, or unexplained weight change
A single TSH is inexpensive and available through our laboratory, and it is included in several health check packages.
Thyroid disease is easy to test for, straightforward to treat, and easy to miss because its symptoms sound like ordinary tiredness. If several of the symptoms in this article apply to you, a single blood test settles the question.
Our endocrinology and general medicine departments at T. Nagar manage thyroid conditions, including in pregnancy.
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