Subclinical thyrotoxicosis

We continue the theme of erased, “disguised” states in endocrinology. First you need to define the concepts.

If you have the following symptoms: feeling of internal tremors, anxiety, nervousness, rapid heartbeat, increased sweating, slight spontaneous weight loss, tenderness in the thyroid gland, fever – an endocrinologist, therapist, or other doctor may send you a hormone test.

The following picture: in the analyzes, a reduced TSH below 0.4 mIU / ml (below the laboratory’s lower limit!) With a normal free T4 level and / or a normal free T3 level is the concept of subclinical thyrotoxicosis.

Most experts have adopted the definition of subclinical thyrotoxicosis (STyr) – “This is a phenomenon in which a reduced level of TSH is determined at normal levels of free T3 and T4” (according to V. Fadeyev).

Determining the level of TSH is the most frequent hormonal test in the world! Its reduced or suppressed level requires interpretation quite often.

If everything is clear with the true thyrotoxicosis syndrome, then with its erased form – “subclinical thyrotoxicosis”, the endocrinologist will still have to smash his head.

Subclinical thyrotoxicosis (the official abbreviation is STyr) may or may not have noticeable symptoms. But this symptom is both “subclinical” and the main questions here will be: is it dangerous? And should this condition be treated? To clarify the first question, it is necessary to find out the reason for the appearance of STyr.

The reasons may be:

multinodular toxic goiter
single-nodular goiter with transformation into a toxic adenoma (if the node size is more than 2.5 cm)
Hashi-toxicosis with AIT
debut of DTZ (diffuse toxic goiter) in the erased version,
STyr as a symptom of a tumor located outside the thyroid gland (eg, lung tumor)
overdose of L-thyroxine
the effect of other drugs (for example, after an X-ray contrast study using a large dose of iodine)
syndrome of euthyroid pathology, etc.
Naturally, the doctor determines the cause, you can only help him – telling in detail about the change in well-being over the next 3-6 months.

An interesting fact: it happens – a physiological decrease in TSH from 0.1 – 0.39, typical for the first trimester of pregnancy, but with the conception of twins, the TSH level can drop to 0.005 mIU / ml – and this is not a pathology. Therefore, before starting diagnostics and treatment, young women, and sometimes women after 45 years old, need to determine with the help of a test or blood test for hCG – are you pregnant?

To clarify the diagnosis, a detailed blood test is taken for thyroid hormones: TSH, free T4, free T3, antibodies to TPO, antibodies to TG, antibodies to the TSH receptor. The doctor decides whether to do a thyroid scintigraphy or an iodine uptake curve, less often an MRI of the neck organs.

In order to determine the treatment, take into account:

the cause of STyr
patient age
concomitant diseases, especially cardiovascular, stroke, the presence of atrial fibrillation or atrial fibrillation, heart failure and some others
the severity of the condition.

The severity of the STIR. There are only two of them

Grade 1 – with a TSH level of 0.1-0.39 mIU / ml

Grade 2 – with a TSH level below 0.1 mIU / ml.

In addition, sublinic thyrotoxicosis can be persistent (permanent) or transient (transient) – therapy will also depend on this.

STyr treatment is required for the following groups of patients:

patients under 65 years of age, with symptoms of thyrotoxicosis, especially if antibodies to the TSH receptor are elevated or the uptake of iodine is increased during the iodine uptake curve / signs of thyrotoxicosis on thyroid scintigraphy
patients over 65 years of age with / without signs of TTZ, with ischemic heart disease, angina pectoris, atrial fibrillation, Pritzmetal’s angina, stroke or transient ischemic attack
in patients with a proven cause of STIR – toxic adenoma or multinodular toxic goiter, treatment is more often with radioiodine
Surgical treatment is recommended for patients with STIR in combination with a very large goiter, symptoms of compression compression), concomitant hyperparathyroidism or suspected thyroid cancer
in addition, the treatment of subclinical thyrotoxicosis is indicated for severe osteoporosis with or without a history of fractures, since STIR increases the risk of fractures in elderly patients at times (especially over 65 years)
Thyrostatic drugs (Tyrozol, Mercazolil, Propicil) are the first choice in the treatment of young patients with Graves ‘disease (diffuse-toxic goiter) with STIR of the 2nd degree, and in patients over 65 years of age with Graves’ disease with STIR 1- degree, since the probability of remission after 12-18 months of therapy with thyreostatics is high and can reach 40-50%.

Radioactive iodine therapy is indicated in a situation of poor tolerance of thyreostatics, as well as in case of recurrence of thyrotoxicosis and in patients with concomitant cardiac pathology.

If the decision is made for lifelong therapy with thyrostatics, such cases also happen (when it is impossible to operate on the thyroid gland) – it must be remembered that these drugs can cause a sharp drop in the level of leukocytes – leukopenia with the transition to agranulocytosis, angina, that is, it is necessary periodically (1 time in 3 months .) control the clinical blood test and, preferably, liver biochemistry – ALT, AST, GGTP.

In other cases, monitoring the state of the thyroid gland, primarily the state of the hormonal background, is shown, first monitoring TSH, free T4, free T3 after 3 months, and in the absence of symptoms and hormone level dynamics – monitoring tests every 6-12 months.