Pregnenolone is a steroid hormone that is synthesized from cholesterol mainly in the adrenal glands. It is an important intermediate in the formation of other steroid hormones: cortisol, aldosterone, estrogens, progesterone, testosterone, and others. In addition, pregnenolone is produced in certain structures of the brain, where it acts as a neurosteroid, participating in the development of neurons, the process of myelination and exerting a neuroprotective effect. Determining the level of pregnenolone is most often used in the diagnosis of adrenogenital syndrome, a congenital hyperplasia of the adrenal cortex associated with a deficiency of one of the enzymes of steroid hormone synthesis. The lack of these enzymes leads to a decrease in the production of end hormones and a compensatory increase in adrenal stimulation from the pituitary gland. As a result, synthesis intermediates, including pregnenolone, accumulate. The study can be performed both in blood and in saliva. Saliva analysis allows you to determine the free, biologically active fraction of the hormone, since the protein-bound part does not pass through the salivary glands. This makes it possible to more accurately assess the level of the hormone available for interaction with the receptors of target organs.