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Subclinical hypothyroidism is a form of hypothyroidism that produces sparse, very difficult-to-see symptoms. Therefore, early diagnosis of the disease is not easy, which may have serious consequences, including development of overt hypothyroidism or heart disease. What are the causes of subclinical hypothyroidism? What is its treatment?


  1. Subclinical (latent) hypothyroidism - causes and risk factors
  2. Subclinical (latent) hypothyroidism - symptoms
  3. Subclinical (latent) hypothyroidism - complications
  4. Subclinical (latent) hypothyroidism - diagnosis
  5. Subclinical (latent) hypothyroidism - treatment

Subclinical (latent, subclinical) hypothyroidism(SNT) is a disorder of the thyroid gland in which there is an increase in the concentration of thyrotropin (TSH) in the blood above the upper limit of normal (i.e. 4.5 mIU / l), with the correct concentration of free thyroxine (fT4) and triiodothyronine (fT3).

Subclinical hypothyroidism is the mildest form of hypothyroidism. There is also a moderate and severe form.

Subclinical (latent) hypothyroidism - causes and risk factors

The cause of congenital subclinical hypothyroidism may be dyshormonogenesis - a disturbance in the biosynthesis of thyroid hormones, which is hereditary.

The causes of acquired subclinical hypothyroidism may be: autoimmune thyroid diseases (especially chronic lymphocytic thyroiditis, i.e. Hashimoto's disease), thyroid gland atrophy, previous treatment of hyperthyroidism (radioactive iodine therapy or thyroid removal). In some cases, the disease may be associated with iodine deficiency, type 1 diabetes mellitus, Down's syndrome, or prior radiotherapy to the head or neck.

Some medications, such as lithium, iodine derivatives, anti-thyroid medications, antiepileptic medications (especially carbamazepine and valproic acid) may contribute to SNT.

It's good to know that subclinical hypothyroidism is more common in women than in men, especially after the age of 60.

Subclinical(latent) hypothyroidism - symptoms

Symptoms of subclinical hypothyroidism are very discreet and difficult to notice, therefore SNT is called hypothyroidism little symptomatic or poorly symptomatic. Adults may experience headaches, cold intolerance, constipation, depressed mood, chronic fatigue, and even depression.

In young children, subclinical hypothyroidism is manifested by prolonged jaundice of newborns, delay in mental and physical development of the child, e.g. abnormal growth, difficulty in eating, reduced mobility, hoarse voice, cold, flaky skin.

In older children it is found: growth inhibition, delayed puberty, learning difficulties, as well as intolerance to cold, constipation, drowsiness, slow speech, headaches, dry, brittle and thin hair, dry and rough skin.


Subclinical (latent) hypothyroidism - complications

Subclinical hypothyroidism may not only lead to the development of overt hypothyroidism (the higher the baseline TSH concentration, the greater the likelihood of further development of hypothyroidism). The consequence of the lack of SNT treatment may also be lipid disorders (increased concentration of total cholesterol and LDL fraction coexists with TSH higher than 10 mIU / l), and thus - cardiovascular diseases.

Scientific research proves that subclinical hypothyroidism is associated with a higher risk of cardiovascular disease and higher mortality from these diseases, but only in people under 65 (but no such relationship has been found in people over 65 years).

In addition, neurological dysfunctions (sensory and motor neurogenic disorders, skeletal muscle dysfunctions) and mental disorders (affective and psychotic) may appear.

In womenin pregnancy, subclinical hypothyroidismincreases the risk of miscarriage, and in women of reproductive age it can lead to ovulation disorders and menstrual disorders, and reduce fertility.

CHECK>>What are the effects of thyroid disease?

Subclinical (latent) hypothyroidism - diagnosis

Blood tests and levels of thyroid stimulating hormone (TSH), free thyroxine (fT4), free triiodothyronine (fT3), anti-thyroglobulin and anti-peroxidase antibodies as well as cholesterol levels, which in most cases are elevated, are required.

During diagnosticsother causes of increased TSH levels should be ruled out, e.g. taking certain medications, e.g. metoclopramide, H2-blockers, neuroleptics, lithium, iodine.

  • Testing of thyroid hormones - thyroxine (fT4) and thyrotropin (TSH)
  • Extended thyroid profile - tests evaluating thyroid function

Subclinical (latent) hypothyroidism - treatment

Currently, there are no uniform rules for the management of subclinical hypothyroidism, as there is no common consensus on the value of TSH as an indication for treatment. Therefore, the decision on when to administer thyroid hormones (L-thyroxine is the drug of choice) should be considered on an individual basis.

Not all subclinical hypothyroidism requires treatment. Treatment may not be necessary for people over the age of 65 because subclinical hypothyroidism does not increase their risk of cardiovascular disease.

In turn, in people aged 85-89, elevated TSH levels were not associated with deterioration of performance, cognitive functions or depression. Research also suggests that in people over 80 years of age, elevated TSH levels may extend life expectancy.

Read also:

  • Primary, Secondary, and Tertiary Hypothyroidism
  • Congenital Hypothyroidism - Causes, Symptoms, Screening Test and Treatment
  • Hypothyroidism: Adequate Diet for Hypothyroidism
  • Hypothyroidism diet: sample menu
About the authorMonika Majewska A journalist specializing in he alth issues, especially in the areas of medicine, he alth protection and he althy eating. Author of news, guides, interviews with experts and reports. Participant of the largest Polish National Medical Conference "Polish woman in Europe", organized by the "Journalists for He alth" Association, as well as specialist workshops and seminars for journalists organized by the Association.

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