Isohormones are hormones synthesized in the body and responsible for various functions of the internal environment of the body. However, they cannot communicate with the receptors of their cells, since their structure differs from the structure of natural hormones. Hormone isoforms are found primarily in animals and plants to regulate metabolic processes and adapt to changing environmental conditions. Typical representatives of this group of hormonal molecules include thyroxine, thyrocalcitonin, somatostatin, cortisol, gonadotropins, lipocortin and others.