A plain-English tour of cortisol, thyroid, insulin, estrogen and testosterone — and how they talk to each other.
Aug 26, 2026
8 min read
Dr. Elena Marquez
Hormones rarely misbehave alone. Read one in isolation and you get a number; read five together and you get an explanation. These are the ones we run first, and what each one is actually telling you.
Cortisol, thyroid and insulin
Cortisol should be high in the morning and low at night — the shape matters more than any single value, which is why we draw it twice. Thyroid sets the pace underneath everything, and TSH alone misses the picture without free T3 and T4. Insulin is the earliest marker of metabolic drift, often abnormal years before glucose is.
Oestradiol and testosterone
Both fall with age, both affect mood, sleep, strength and libido in every body, and both need context: where you are in your cycle, what time you drew, what you were training that week. Without that context the number is close to meaningless.
The practical takeaway: test them together, test at the right time, and re-test before you conclude anything from a single reading.
Dr. Elena Marquez
Endocrinologist, Verdia
