Causes of a low thyroid count include surgical removal of a thyroid gland, autoimmune diseases and radiation treatment, notes Healthline. Other causes of this condition include certain medications, pituitary diseases and infiltration. This condition is more common in women who are over 50 years.
Autoimmune thyroiditis and Grave's disease trigger the production of antibodies that attack the thyroid gland, explains Healthline. Viruses can also cause the condition. The most common types of autoimmune diseases include Hashimoto’s thyroiditis and atrophic thyroiditis.
Radiation treatment usually alleviates the symptoms of Hodgkin's lymphoma and cancers of the head and neck, according to Healthline. This may lead to insufficient thyroid hormone production by the gland, resulting in inefficient metabolism.
Children with thyroid glands that don't function properly or those born without the glands may suffer from a condition known as congenital hypothyroidism, states Healthline. Too little or excessive iodine may also cause this condition. Stroke, trauma or a tumor can damage the pituitary gland, thus inhibiting the production of thyroxine and causing hypothyroidism.
Medications for viruses and cancer, such as interleukin 2, and lithium, which is used to treat bipolar diseases, may cause a low thyroid count, explains Healthline. Other medications that can result in this condition include amiodarone, which is a medication for severe ventricular arrhythmias.