Thyroid problems, and why they are missed

Thyroid disease is common, affects women considerably more often than men, and becomes more likely with age — and its symptoms are so unremarkable that people live with them for years.

What the thyroid does

It produces hormones that set the metabolic rate of essentially every tissue.

The pituitary monitors the level and adjusts its own output — thyroid stimulating hormone — to compensate, which is why TSH rises when the thyroid is failing and falls when it is overactive.

Understanding that inversion prevents most of the confusion people have when reading their own results.

Underactive thyroid

The more common problem, usually caused by autoimmune thyroiditis, and sometimes following treatment for an overactive thyroid, surgery, radiotherapy, certain medications, or iodine deficiency in regions where that persists.

Symptoms: fatigue, weight gain, cold intolerance, dry skin, hair thinning, constipation, low mood, poor concentration, muscle aches, heavy or irregular periods, and slowed heart rate.

Each of these has a dozen other explanations, which is exactly why it is missed.

Treatment is levothyroxine, taken daily, on an empty stomach and separated from calcium, iron and several other medications that impair absorption — which is a genuinely important practical point that is often omitted.

Dose is adjusted against TSH after around six to eight weeks, since the system responds slowly.

Overactive thyroid

Most commonly Graves' disease, an autoimmune condition, and sometimes nodules producing hormone autonomously or a transient inflammatory thyroiditis.

Symptoms: weight loss despite appetite, heat intolerance, sweating, palpitations, tremor, anxiety, irritability, insomnia, frequent bowel movements, and in Graves' disease eye changes that require specific attention.

Treatment options are antithyroid medication, radioactive iodine and surgery, each with different consequences and different likelihoods of eventual underactivity.

Untreated, it carries genuine risks including atrial fibrillation and bone loss, so it is not something to observe indefinitely.

Subclinical disease

Where most of the argument is.

Subclinical hypothyroidism means a raised TSH with normal thyroid hormone levels.

It is common, particularly in older people, and a proportion resolves spontaneously — which is why repeating the test after an interval before treating is standard.

Guidelines generally reserve treatment for higher TSH elevations, for those with symptoms and positive antibodies, for younger patients, and for pregnancy or those planning it, where thresholds are different and the stakes higher.

Treating mild elevations in older adults has not shown benefit in trials and carries risks of overtreatment, which include atrial fibrillation and bone loss.

Why people remain symptomatic on treatment

A genuine and frequently dismissed problem.

A proportion of treated patients report persistent symptoms despite normalised TSH.

Possible explanations include coexisting conditions producing the same symptoms, expectations of what treatment can resolve, individual variation in how thyroxine is converted to the active hormone, and the limits of TSH as a marker of tissue-level status.

Combination treatment with liothyronine remains contested: trials have not shown consistent benefit overall, though some patients report improvement, and guidance in several countries permits a specialist trial in selected cases.

Desiccated animal thyroid extract is used by some patients and is not recommended in most guidelines because of variable hormone content.

The reasonable position is that persistent symptoms deserve investigation of other causes rather than either dismissal or automatic escalation of thyroid treatment.

Pregnancy

Where the stakes are highest.

Thyroid requirements increase in pregnancy, and women on treatment generally need a dose increase early, which is why anyone treated for hypothyroidism should contact their clinician as soon as they know they are pregnant.

Untreated hypothyroidism in pregnancy is associated with adverse outcomes, and thresholds for treatment are lower than outside pregnancy.

Postpartum thyroiditis affects a notable minority of women in the year after birth and is frequently mistaken for postnatal depression or ordinary exhaustion.

Nodules and lumps

Thyroid nodules are extremely common, particularly with age, and the overwhelming majority are benign.

Any new lump in the neck warrants assessment, usually with examination, blood tests and ultrasound, and biopsy where features are suspicious.

Incidental detection through scans done for other reasons has increased substantially, which has produced a documented rise in diagnosis of small thyroid cancers without a corresponding rise in mortality — a recognised overdiagnosis problem that has changed how small nodules are managed.

The practical summary

If you have several of the symptoms persistently, ask for the test, which is cheap and definitive.

If you are on treatment, take it consistently and away from interfering substances.

And if you remain unwell on treatment with normal results, that is a reason to look further rather than a reason to be told nothing is wrong.

General information only, not medical advice. Consult a qualified clinician about symptoms or test results, and do not adjust thyroid medication yourself.