Across the day
Circadian rhythms are biological cycles lasting about 24 hours. They influence hormone release as
well as sleep, appetite, and body temperature. This is one reason the timing of an assessment can
matter; the collection instructions should specify what is needed for the order.
NIH: circadian rhythms
Across life stages
Hormone production also changes across life stages. During the menopause transition, for example,
the ovaries’ production of reproductive hormones changes and menstrual patterns can become
irregular. That history helps distinguish an expected transition from questions that need further
evaluation.
MedlinePlus: menopause
At the time of collection
Medicines, supplements, food, exercise, and other factors can affect some laboratory results. The
practice should collect the relevant history and communicate the preparation instructions supplied
for the order. Patients should discuss medication changes with their clinician.
MedlinePlus: understanding laboratory results