The cause-and-effect relationship between thyroid dysfunction and obesity has been somewhat questioned in recent years.
In particular, when an isolated increase in TSH (<10) is observed against the background of obesity and is not accompanied by abnormalities in other laboratory parameters, this change may be caused by obesity itself, and not vice versa.
The fact is that Hypothyroidism Treatment results in only a small reduction in weight - most often less than 10% of body weight.
This gives reason to believe that obesity is not always of secondary origin and Hormonal changes may be a compensatory event in response to obesity.
In addition to TSH, other parameters should be considered for differentiation. If there is an increase in autoimmune markers, a decrease in thyroid hormones (FT4 and FT3), and other symptoms characteristic of hypothyroidism, this definitely indicates the presence of a primary thyroid disease.
Most obese individuals do not experience functional or structural changes in the thyroid gland.
In other cases, according to the analysis of conducted studies, the following type of effect occurs: losing weight leads to a decrease in TSH and FT3, while gaining weight, on the contrary, increases these indicators.
When obesity is the cause and not the result, the free thyroxine (FT4) level is normal or close to the upper limit of normal.
This distinguishes it from true subclinical hypothyroidism (a type of hypothyroidism in which TSH is elevated but FT4 remains within the formal normal range), which is more characterized by a near-normal FT4 level.
Hypothyroidism In addition to the increased risk of developing, obesity can also cause other types of damage to the thyroid gland.
According to studies, obesity also increases the risk of developing autoimmune thyroiditis.
This effect is particularly pronounced in children and is manifested by an increase in anti-thyroid antibodies (Anti-TPO, Anti-TG).
Changes can also be observed on ultrasound, which is manifested by diffusely decreased echogenicity and an increase in the total volume of the gland.
Often these manifestations coincide with the signs that are characteristic of Hashimoto's thyroiditis.
Therefore, the diagnosis of autoimmune thyroiditis in the setting of obesity should not be made solely on the basis of ultrasonography, without antibody testing, to avoid diagnostic errors.
An increase in TSH causes the thyroid cells to activate and grow in size, resulting in an increase in the total volume/size of the entire gland.
For the same reason, the risk of developing nodules in the gland, including malignant tumors, is high.
Treatment features
Obesity-induced hyperthyrotropinemia (high TSH) is transient and will resolve with weight loss.
Even a small change in lifestyle, which manifests itself By increasing physical activity And the development of muscle mass, even without a change in body mass index, leads to a decrease in TSH and FT4 levels.
Ultrasound changes are also subject to normalization.
Some recommendations state that this condition does not require replacement therapy. However, it is important to consider the effects of elevated TSH on the structure of the gland, which can lead to the formation of a thyroid tumor. Especially if weight loss and normalization do not occur.
In addition, if proper differentiation is not achieved and obesity is accompanied by “true” hypothyroidism, if left untreated, it can further increase the risks associated with obesity in terms of developing cardiovascular diseases and various metabolic disorders.
Hypothyroidism causes disruption of fat metabolism and in this regard also contributes to vascular damage.
Finally, untreated hypothyroidism can be a cause of failure in weight loss efforts.
Therefore, since both testing and treatment are inexpensive and safe, it is better to routinely screen for hypothyroidism in obese patients.
Therefore, in both cases, hormonal balance must be corrected with appropriate treatment.
However, the patient should be informed that even in the case of primary hypothyroidism, the weight gain caused by it is usually mild.
Therefore, he should not have excessive expectations that treating hypothyroidism in isolation without other interventions will produce significant results against obesity.
Moreover, the desired result will not be achieved when obesity is the primary cause and thyroid dysfunction is only its consequence.
Author: Elga Giorgadze (Endocrinologist)
