Hypothyroidism: Prevention, Diagnosis, and When to See a Doctor

Hypothyroidism is one of the most common endocrine conditions and at the same time one of the simplest to diagnose: in most cases a few blood tests are enough. The problem is that the symptoms develop slowly and are easily attributed to fatigue or excessive training. The editorial team explains what can really be done for prevention, how to undergo an examination without errors, and in which situations not to postpone a visit to the doctor.

Prevention: what depends on us

The most frequent cause of hypothyroidism — autoimmune thyroiditis — cannot be prevented today: there are no proven ways to stop the appearance of antibodies to the thyroid gland. Neither a gluten-free diet, nor selenium, nor specific “thyroid” complexes have convincing evidence of a preventive effect in healthy people.

A truly manageable factor is adequate iodine intake. For Ukraine, which historically belongs to iodine-deficient regions, the simplest way recommended by the WHO is the use of iodized salt in usual amounts. For pregnant and breastfeeding women, a doctor may additionally prescribe iodine preparations, because the need increases during this period.

At the same time, one should not overdo it in the opposite direction. An excess of iodine from kelp, iodine-containing “detox” supplements, or the thoughtless intake of high-dose preparations can provoke both hypo- and hyperthyroidism in susceptible people, especially in the presence of antibodies or nodules. The rule “more is better” does not work here.

For athletes, a separate block of prevention is avoiding situations that disrupt the work of the hormonal axis: prolonged energy deficiency and self-directed intake of thyroid hormones. Adequate nutrition that covers the expenditure on training protects against low-T3 syndrome, and refusing hormones “for cutting” protects against suppression of one's own gland.

• iodized salt instead of regular salt, without an excess of iodine supplements;
• a diet that matches energy expenditure, especially during periods of weight loss;
• refusing thyroid hormones without medical indications;
• regular TSH screening if there is a family history or other autoimmune diseases.

Which tests to take

The main screening test is thyroid-stimulating hormone (TSH). In primary hypothyroidism it rises earlier than the level of gland hormones falls, so a normal TSH in most cases allows primary insufficiency to be ruled out. The reference interval in most laboratories is approximately 0.4–4.0 mIU/L, but the exact limits depend on the method.

If TSH is deviated, free thyroxine (free T4) is added. It is exactly the ratio of TSH to free T4 that determines whether we are dealing with overt, subclinical, or central hypothyroidism. Free T3 is usually of little use for diagnosing hypothyroidism, although in athletes it can be useful for detecting energy deficiency.

Antibodies to thyroid peroxidase (anti-TPO) confirm the autoimmune nature of the process and help assess the risk of progression of subclinical hypothyroidism into overt. Ultrasound examination of the thyroid gland is ordered for palpable changes, nodules, or enlargement of the gland, and not as a routine test for everyone.

For the results to be reliable, blood is given in the morning, in a stable state — not during an acute infection and not right after competitions or a hard week of training. Supplements with high doses of biotin should be stopped at least a few days before the test, because it distorts the results of immunochemical tests. If you are already taking levothyroxine, the doctor will advise whether to give blood before the morning tablet.

How the results are interpreted

The classic picture of primary hypothyroidism is elevated TSH and reduced free T4. If TSH is elevated but free T4 is normal, this is called subclinical hypothyroidism. A single moderate elevation of TSH is confirmed by a repeat test after 6–12 weeks: TSH fluctuates over the course of the day, rises during recovery after an illness, and in older people.

A reduced free T4 with a normal or reduced TSH may indicate central hypothyroidism — a rare condition that requires examination of the pituitary. A similar picture occurs after withdrawal of self-administered thyroid hormones, while the axis recovers, and in severe general illnesses.

The decision about treatment of subclinical hypothyroidism is made individually. The European Thyroid Association (Pearce et al., 2013) recommends considering therapy at a TSH above 10 mIU/L, and at lower values — taking into account age, symptoms, the presence of antibodies, and pregnancy planning.

When to see a doctor

An endocrinologist or family doctor should be seen if, over several weeks, unexplained fatigue, drowsiness, sensitivity to cold, dry skin, hair loss, constipation, facial puffiness, weight gain without dietary changes, or menstrual cycle disturbances persist — especially if rest and load correction do not help.

TSH screening is appropriate even without symptoms if there is a thyroid disease in the family, you have other autoimmune diseases (type 1 diabetes, celiac disease, vitiligo), you are planning a pregnancy, or you have had surgery or irradiation in the neck area.

Emergency attention is required for a rapidly increasing enlargement of the neck, difficulty swallowing or breathing, as well as a sharp deterioration with pronounced weakness, confusion, and hypothermia — signs of severe decompensated hypothyroidism, which occur rarely but are life-threatening.

Athletes who have taken or stopped thyroid hormones on their own and who have pronounced symptoms should see a doctor and honestly tell them about it: the correct interpretation of the tests and the management strategy depend on it.

Treatment and training

The standard treatment of hypothyroidism is replacement therapy with levothyroxine, a synthetic analog of T4 (Jonklaas et al., 2014). The dose is selected by the doctor according to body weight, age, comorbidities, and the TSH level, which is monitored 6–8 weeks after each dose change. The goal is to keep TSH within the normal range, not to “rev up” metabolism.

Levothyroxine is taken on an empty stomach, usually 30–60 minutes before breakfast, washed down with water. Coffee, iron and calcium preparations, protein shakes with soy, and some antacids reduce its absorption, so they are taken at an interval of a few hours. Athletes with a large number of supplements should draw up a clear schedule with a doctor.

Levothyroxine is not on the WADA Prohibited List, so treatment of hypothyroidism does not interfere with participation in competitions. At the same time, increasing the dose on one's own for the purpose of weight loss makes the therapy dangerous — an excess of hormones causes tachycardia, arrhythmias, and loss of bone mass.

Against the background of compensated hypothyroidism a person can train fully. At the start of treatment, while TSH has not yet normalized, it is reasonable to temporarily reduce volume and intensity and gradually return to the usual regimen, guided by well-being and tests.

Editorial conclusions

Primary prevention of autoimmune hypothyroidism is impossible, but you can ensure adequate iodine intake, without excess, avoid prolonged energy deficiency, and not take thyroid hormones without indications.

Diagnosis begins with TSH, and if it is deviated — with free T4 and antibodies to TPO. The result should be confirmed with a repeat test, giving blood in a stable state and without biotin supplements.

With confirmed hypothyroidism, treatment with levothyroxine allows a person to live and train fully, and the drug itself is not banned in sport.

We also recommend reading our materials on the causes of hypothyroidism in athletes, on the TSH test, and on the diagnosis of hyperthyroidism.

References

1. Jonklaas J, Bianco AC, Bauer AJ, et al. Guidelines for the treatment of hypothyroidism: prepared by the American Thyroid Association Task Force on Thyroid Hormone Replacement. Thyroid. 2014;24(12):1670–1751.
2. Garber JR, Cobin RH, Gharib H, et al. Clinical practice guidelines for hypothyroidism in adults: cosponsored by the American Association of Clinical Endocrinologists and the American Thyroid Association. Thyroid. 2012;22(12):1200–1235.
3. Pearce SHS, Brabant G, Duntas LH, et al. 2013 ETA guideline: management of subclinical hypothyroidism. Eur Thyroid J. 2013;2(4):215–228.
4. Chaker L, Bianco AC, Jonklaas J, Peeters RP. Hypothyroidism. Lancet. 2017;390(10101):1550–1562.
5. Mountjoy M, Ackerman KE, Bailey DM, et al. 2023 International Olympic Committee's (IOC) consensus statement on Relative Energy Deficiency in Sport (REDs). Br J Sports Med. 2023;57(17):1073–1097.
6. World Anti-Doping Agency. The World Anti-Doping Code: International Standard — Prohibited List. Montreal: WADA; чинна редакція.