i think there are distinct stages,i'm still researching but my BF has adrenal issues and has very low histamines....he's 2 1/2 weeks into treatment and the change is dramatic...i think insurance will cover if your doc orders the labs but i just paid for it thru ineedlabs.com...the big difference we've ntices is that he never gets sick or catches a cold and i catch one easily...i also have food and chemical allergies while he has none at all....i don't get depressed and gets gets major depression...i have more bipolar type symptoms....this all coincides with low and high histamines types....plus i'm super type A and he has a hard time motivating....