Cortisol (morning)

The main stress hormone, measured here as the morning peak of a rhythm that falls through the day.

It sets blood sugar, blood pressure and how you respond to illness, and both too much and too little cause real symptoms.

The time of the draw is the single most important thing about this number -- an afternoon sample is expected to be low and says nothing. It also measures hormone bound to protein, so the pill and pregnancy raise it without more active hormone.

Worth discussing a low morning value, especially with persistent fatigue or dizziness on standing.