Hormones are chemical messengers that control how our bodies function.  They allow our bodies to maintain fairly constant in temperature, weight and ability despite huge daily fluxes in food intake energy use and external environment.  Our stability is due to the modulating influence of our hormones.  

Hormones work in concert, with multiple layers of feedback and coordination.  They are also heavily influenced by detoxification processes, nutrition, and  immune system imbalances.  For this reason, symptoms of hormonal imbalance need to be carefully investigated before being treated. Fatigue can be caused by a deficiency in thyroid hormone, adrenal hormones, estrogen, progesterone, testosterone, growth hormone or DHEA, but  is most often caused by a combination of hormonal and non hormonal factors.  

Andropause (low testosterone)
Thyroid problems
Adrenal Imbalances