Thyroid disease is common, frequently missed for years, diagnosed with a single blood test, and very treatable. An underactive thyroid causes exhaustion, weight gain, feeling cold, dry skin, constipation and low mood. An overactive one causes exhaustion with weight loss, a racing heart, anxiety, tremor and heat intolerance. The reason it goes undiagnosed is that every one of those symptoms has an easier explanation — age, stress, menopause, a busy life.
If that list describes your last six months, ask us for a TSH test. It is one blood draw, and our laboratory is in the building.
What the thyroid does
A small gland at the front of your neck that sets your metabolic rate — how fast your body uses energy. Too little hormone and everything slows down. Too much and everything speeds up. Because it influences nearly every system, the symptoms are diffuse, which is exactly why they get attributed elsewhere.
Underactive (hypothyroidism) — the common one
- Exhaustion that sleep does not fix
- Weight gain, or difficulty losing weight despite no change in habits
- Feeling cold when others are comfortable
- Dry skin, brittle nails, thinning hair — including the outer third of the eyebrows
- Constipation
- Low mood, or depression that does not respond as expected to treatment
- Brain fog, poor concentration, forgetfulness
- Muscle aches, cramps, weakness
- Heavy or irregular periods, or difficulty conceiving
- Hoarse voice
- Slow heart rate
- Raised cholesterol with no other explanation
The most common cause in the US is Hashimoto’s thyroiditis, an autoimmune condition. It runs in families and is considerably more common in women.
Overactive (hyperthyroidism)
- Weight loss despite a normal or increased appetite
- Racing or irregular heartbeat, palpitations
- Anxiety, irritability, restlessness
- Tremor, usually of the hands
- Heat intolerance and increased sweating — genuinely miserable in an Arizona summer
- Difficulty sleeping
- Frequent bowel movements
- Muscle weakness, especially in the thighs
- Lighter or absent periods
- Eye changes — bulging, grittiness, double vision (associated with Graves’ disease)
- A visible swelling in the neck
One urgent note: an overactive thyroid can cause atrial fibrillation, an irregular heart rhythm that raises stroke risk. Palpitations with breathlessness or dizziness should be assessed rather than tolerated.
Who should be tested
Ask for a test if you have the symptoms above, and particularly if you also have: a family history of thyroid disease, another autoimmune condition such as type 1 diabetes or coeliac disease, a history of neck radiation or thyroid surgery, or you take lithium or amiodarone.
Also worth testing: after pregnancy, since postpartum thyroiditis is common and easily mistaken for ordinary new-parent exhaustion; during pregnancy or while trying to conceive, because untreated thyroid disease affects both fertility and fetal development; and in older adults with new atrial fibrillation, unexplained weight loss, or cognitive change, where thyroid disease often presents atypically and gets attributed to ageing.
Women are affected far more often than men, and risk rises with age — which in our community means a lot of people who have never had it checked.
The test, and what the numbers mean
TSH is the screening test, and usually the only one needed first. Confusingly, TSH moves *opposite* to thyroid function: a high TSH means an underactive thyroid, because the pituitary is shouting at a gland that is not responding. A low TSH means overactive.
If TSH is abnormal we add free T4, sometimes free T3, and thyroid antibodies to identify an autoimmune cause. A neck ultrasound follows if there is a lump or swelling.
Two honest caveats. Reference ranges vary between laboratories, and there is genuine clinical debate about borderline results — a mildly raised TSH with no symptoms is not automatically treated, and treating it reflexively is not harmless. And normal TSH with persistent symptoms does not end the conversation: it means we look elsewhere, at iron, vitamin B12, vitamin D, blood sugar, sleep apnoea, or mood. See sudden fatigue and weakness.
Be wary of direct-to-consumer “full thyroid panels” and supplements sold for thyroid support. Some contain actual thyroid hormone or large iodine doses, both of which can do real harm and can make a genuine problem harder to diagnose.
Treatment, plainly
Underactive: a daily tablet of levothyroxine, a synthetic version of the hormone you are short of. Inexpensive, effective, and for most people a permanent but entirely unremarkable part of the day. Take it on an empty stomach, and keep calcium, iron and antacids at least four hours apart from it, since they block absorption. We recheck TSH about six to eight weeks after any dose change, then annually once stable.
Overactive: options are anti-thyroid medication, radioactive iodine, or surgery, depending on the cause and your circumstances. Beta blockers often help the symptoms while a longer-term plan takes effect.
Thyroid nodules are common and the large majority are benign. A lump in the neck still warrants examination and usually an ultrasound.
Once treated, most people feel substantially better — and a good number describe getting years back that they had written off as ageing.
Where to go
Book our Medical Clinic for a TSH test and a proper look at the symptoms. Blood work is drawn and run in this building, so results usually come back the same day. Call (602) 671-7981.
Come with notes: when it started, what changed, your weight trend, your periods if relevant, your family history, and everything you take including supplements.
Come to our Emergency Room — open 24 hours — for a rapid irregular heartbeat with chest pain or breathlessness, severe agitation with a high temperature, or profound weakness and confusion. Both thyroid extremes have rare but genuine emergencies: (602) 671-7990.
Related: sleep problems · women’s health 45 to 75
Sources
- American Thyroid Association — Hypothyroidism and hyperthyroidism
- NIDDK — Hypothyroidism
- NIDDK — Hyperthyroidism
- US Preventive Services Task Force — Thyroid dysfunction screening