Steroid Hormones

5 substance families belong to the steroid hormones. In each family there are several members, the most important of which is usually called the representative.

1. estrogens: main representatives: estradiol

2. progestin; main representative: progesterone

3. androgens; main representatives: testosterone

4. mineralocorticoids; main representatives: aldosterone

5. glucocorticoids; main representatives: cortisone

What these substance families have in common is that all of them are produced from the parent substance cholesterol. Due to lipophilia in the blood, steroid hormones are bound to larger transport proteins, usually specific to the hormone in question, protecting them from rapid degradation and excretion. Since only the free hormone, not the bound hormone, is biologically active and there is a balance between the bound and free parts, the transport protein-bound hormone can also be regarded as a circulating storage form. The proportion of unbound, free hormones in lipophilic hormones is less than 5%. The plasma half-lives of this hormone group are relatively long (hours to days). The breakdown of steroid hormones occurs mainly in the liver.