Standard Reference Ranges

Cortisol peaks shortly after waking up and drops to its lowest point around midnight. While specific normal ranges vary slightly depending on the testing laboratory, standard reference ranges for adults generally follow these timelines: [1, 2, 3, 4, 5]

• Early Morning (6:00 a.m. to 8:00 a.m.): 10 to 20 mcg/dL (140 to 690 nmol/L).

• Late Afternoon (Around 4:00 p.m.): 3 to 10 mcg/dL (80 to 270 nmol/L).