Cortisol is known as the stress hormone. It is possible to have both an excess and deficiency in Cortisol. This means during times of stress your cortisol is too high, and the rest of the time your cortisol is too low. Excess Cortisol can cause weight gain, muscle weakness, severe fatigue, and irritability. Deficient Cortisol can cause weakness, fatigue, and low blood pressure. Cortisol levels can be regulated through Testosterone Replacement Therapy (TRT), helping to alleviate your symptoms.