ABSTRACT
The thyroid axis is biologically fascinating and is the target of several common diseases – especially diseases in which the body attacks itself, called autoimmune diseases. The HPT axis performs homeostasis by keeping nearly constant T4 levels, whereas the HPA axis is an input-response circuit, designed to produce a wide range of x3 concentrations according to stress inputs. There are at least 50 such known mutations in the thyroid stimulating hormone (TSH) receptor gene that cause toxic nodules. The mutant cell proliferates and over many years grows to a toxic nodule that causes hyperthyroidism. In infants, hypothyroidism can lead to impaired development of the brain – that is why a TSH test at birth is so important. The most common cause of hypothyroidism is Hashimoto’s disease. In Hashimoto’s disease, white blood cells called T-cells attack and kill thyrocytes. Many people with subclinical disease therefore rely on compensation by gland-mass changes for health.
