What are the causes of elevated serum thyroid stimulating hormone?

The thyroid gland is an important organ in the human body and a key organ for maintaining life and health. The thyroid gland relies on the secretion of serum thyroid-stimulating hormone to maintain the body's needs. However, abnormal secretion of this substance will cause functional damage to the body. For example, high serum thyroid-stimulating hormone is a common phenomenon among women. So, what are the reasons for high serum thyroid-stimulating hormone?

1. Elevated thyroid hormone accompanied by decreased TSH is mostly primary hyperthyroidism caused by diseases of the thyroid gland itself, such as diffuse goiter, thyroid adenoma, etc. When thyroid hormones and TSH levels are elevated, it is usually secondary hyperthyroidism caused by hypothalamic-pituitary dysfunction, such as pituitary adenoma. It is seen in secondary hypothyroidism, diffuse goiter with hyperthyroidism, etc.

2. Decreased thyroid hormone accompanied by increased TSH is mostly caused by primary thyroid dysfunction, such as excessive treatment of primary hyperthyroidism and chronic thyroiditis. Serum thyroid hormone and TSH are both decreased, which is mostly secondary hypothyroidism caused by impaired hypothalamic-pituitary function. It is seen in primary hypothyroidism, thyroid-stimulating hormone-secreting pituitary tumors, adenohypophysiism, and the recovery period of subacute thyroiditis.

3. When hyperthyroidism occurs in the human body, the thyroid hormone (T3, T4) increases, which can feedback inhibit the gland from producing and releasing thyroid stimulating hormone (TSH). Therefore, the TSH content in serum will decrease at this time. Even changes in TSH are more sensitive than those of T3 and T4. For example, subclinical hyperthyroidism refers to a serum TSH level below the lower limit of normal, while T3 and T4 are within the normal range, with no or mild hyperthyroidism symptoms. From this, the important guiding role of TSH in clinical practice is evident.