Hormones are the chemical regulators and messengers of the body.
They are released in very succinct and rhythmic amounts and even the slightest imbalance can have major influences on the processes of the body.
Some hormones are quick acting and quickly subside but most of them embed their molecules in cellular walls and change the expression of DNA - they remain in the wall of the cell often until the cell dies which may range from a few days to a few years.
The body is an analogue device.. Hormones and electrochemical signals propagate in waves throughout the body, smoothly and without break.
Things taken externally which pertain to exact chemicals that are normally produced within the body ie pharmaceutical medicines are digital in the respect that they are either on or off. Off is fine as this leaves the body to do its natural thing but when on, it is on continuously which is against the nature of the body to operate in waves.
The fine balance that the body achieves of its own accord is disrupted by a continuous flow of something which comes from within.. This often leads to inhibition of the natural production of said thing along with downregulation of other factors which depend on coexistent hormones or nervous signals.
The hypothalamic pituitary adrenal axis or HPA is an interplay between the three major endocrine glands which produce 70 % of the body's hormones. This involves signaling hormones produced by the hypothalamus which causes the pituitary gland to produce a hormone whose effect reaches the adrenal glands and produces a further effect. This then has effects on the whole body.
If one takes a hormone that replicates the adrenal gland output (as an example, there is also an axis with the thyroid and organs of sexual development ie testes and ovaries) then this downregulates both the hypothalamic and pituitary output.
If one can imagine that each hormonal chemical does not merely have one target, one purpose then you must understand that even the corticotropins produced by the pituitary have an effect on other tissues before they reach the adrenal gland.. And perhaps the corticotropin-releasing hormone produced by the hypothalamus has an effect on mood or other neurological structures in the brain where it is released and therfore this impact is also reduced to almost nil by the introduction of artificial adrenal hormones.
Adrenal hormones are related to blood pressure, blood composition regulation and the fight flight response and perhaps are a bad example, but if one considers the above in terms of sex hormones, one only has to see the effects puberty has on the body as a whole to understand that the gonadotropins, luteinising hormone and follicle stimulating hormones which rule the productions of progesterone, estrogen and testosterone in the ovaries and testes also have wider effects on the body, the balance of which is destroyed by the digital 1 (as opposed to zero as in binary digits) of pharmaceutically introduced hormonal therapy.
This is especially true over the longer term, and does not necessarily prevent short term hormone therapy for instance taking adrenalin to save your life as single doses are not enough to harm the axis.. It is when the blood concentration is above a certain level for longer than it would be naturally that it starts to become a problem.
Of course, if your body naturally does not produce a hormone anymore, due to aging etc. Then adding that hormone actually helps balance the levels of the - tropin and - releasing hormones whose levels rise dangerously as they try to release a hormone which your body can no longer produce.
So in some instances it is an essential therapy however this situation is almost exclusively reserved for women who have undergone menopause and there are risks associated with it because once again, the hormones are not introduced in a cyclic fashion which is in tune with the human body.