Hormone blood tests
A hormone blood test measures the concentration of a specific hormone in a blood sample. Clinicians combine these results with your symptoms, history, and examination to evaluate how the endocrine system is functioning. Each guide below explains what a test measures and how results are generally interpreted.
Browse blood tests
Testosterone Blood Test Explained
Learn what a testosterone blood test measures, why a clinician may order it, how to prepare, and how high and low results are generally interpreted.
Free Testosterone Test Explained
Understand what a free testosterone test measures, how it differs from total testosterone, why it is ordered, how to prepare, and how results are read.
Estradiol (Estrogen) Blood Test Explained
Learn what an estradiol blood test measures, why clinicians order it, how cycle timing affects preparation, and how high and low results are interpreted.
Progesterone Blood Test Explained
Discover what a progesterone blood test measures, why timing in the menstrual cycle matters, why clinicians order it, and how results are interpreted.
TSH Test: Thyroid Function Explained
Learn what a TSH blood test measures, why it is the first-line thyroid test, how to prepare, and how high and low TSH results are generally interpreted.
Free T4 (Thyroxine) Test Explained
Understand what a free T4 blood test measures, how it complements TSH, why clinicians order it, how to prepare, and how results are generally interpreted.
Free T3 (Triiodothyronine) Test Explained
Learn what a free T3 blood test measures, how it relates to TSH and free T4, why clinicians order it, how to prepare, and how results are interpreted.
Cortisol Blood Test Explained
Learn what a cortisol blood test measures, why timing of day matters, why clinicians order it, how to prepare, and how high and low results are read.
DHEA-Sulfate (DHEA-S) Blood Test Explained
Understand what a DHEA-sulfate blood test measures, why clinicians order it for androgen evaluation, how to prepare, and how results are interpreted.
LH (Luteinizing Hormone) Blood Test Explained
Learn what an LH blood test measures, why clinicians order it for fertility and puberty, how cycle timing affects it, and how results are interpreted.
FSH (Follicle-Stimulating Hormone) Test Explained
Learn what an FSH blood test measures, why clinicians order it for fertility and menopause, how cycle timing matters, and how results are interpreted.
Prolactin Blood Test Explained
Understand what a prolactin blood test measures, why clinicians order it, how to prepare, what can raise prolactin, and how results are interpreted.
SHBG Blood Test Explained
Learn what an SHBG blood test measures, how it affects free hormone levels, why clinicians order it, how to prepare, and how results are interpreted.
IGF-1 Blood Test Explained
Learn what an IGF-1 blood test measures, why it reflects growth hormone activity, why clinicians order it, how to prepare, and how results are read.
Hemoglobin A1c (HbA1c) Test Explained
Learn what an HbA1c blood test measures, why it reflects average blood sugar over months, why clinicians order it, how to prepare, and how results are read.
Fasting Insulin Test Explained
Learn what a fasting insulin blood test measures, why clinicians order it, why fasting matters, and how high and low insulin results are generally interpreted.
AMH (Anti-Mullerian Hormone) Test Explained
Learn what an AMH blood test measures, why it reflects ovarian reserve, why clinicians order it, how to prepare, and how high and low results are read.
Vitamin D Blood Test Explained
Learn what a vitamin D blood test measures, why clinicians order it, how to prepare, and how low and high 25-hydroxyvitamin D results are generally interpreted.
Parathyroid Hormone (PTH) Blood Test Explained
Learn what a PTH blood test measures, why it is checked with calcium, why clinicians order it, how to prepare, and how high and low results are read.
Aldosterone Blood Test Explained
Learn what an aldosterone blood test measures, why it is checked with renin, why clinicians order it, how to prepare, and how results are generally interpreted.
ACTH Blood Test Explained
Learn what an ACTH blood test measures, why it is checked with cortisol, why clinicians order it, how to prepare, and how high and low results are read.
Thyroid Antibodies Test (TPO, Tg, TRAb) Explained
Learn what thyroid antibody tests measure, why TPO, thyroglobulin, and TRAb antibodies are ordered, how to prepare, and how high and low results are read.
Reverse T3 (rT3) Blood Test Explained
Learn what a reverse T3 blood test measures, why it is sometimes ordered, how to prepare, how results are interpreted, and why it is rarely used routinely.
17-Hydroxyprogesterone (17-OHP) Test Explained
Learn what a 17-hydroxyprogesterone test measures, why it is ordered to screen for congenital adrenal hyperplasia, how to prepare, and how results are read.
Renin Blood Test Explained
Learn what a renin blood test measures, why it is ordered with aldosterone to evaluate blood pressure and potassium, how to prepare, and how results are read.
Calcium Blood Test Explained
Learn what a calcium blood test measures, why total and ionized calcium are ordered, how to prepare, how high and low results are read, and related tests.
Plasma Metanephrines Test Explained
Learn what a plasma metanephrines test measures, why it is ordered to screen for pheochromocytoma, how to prepare, and how high and low results are read.
Fasting Glucose Test Explained
Learn what a fasting glucose blood test measures, why it is ordered to screen for diabetes, how to prepare, how high and low results are read, and more.
C-Peptide Blood Test Explained
Learn what a C-peptide blood test measures, why it is ordered, how it reflects insulin production, how to prepare, and how high and low results are read.
Oral Glucose Tolerance Test (OGTT)
Learn what an oral glucose tolerance test measures, why it is ordered, how the glucose challenge works, how to prepare, and how results are interpreted.
Dexamethasone Suppression Test Explained
Learn what a dexamethasone suppression test assesses, why it is ordered for cortisol problems, how the protocol works, how to prepare, and how results read.
ACTH Stimulation Test Explained
Learn what an ACTH stimulation test assesses, why it is ordered, how the adrenal challenge works, how to prepare, and how cortisol responses are read.
24-Hour Urine Cortisol Test Explained
Learn what a 24-hour urine cortisol test measures, why it is ordered, how the collection works, how to prepare, and how high and low results are read.
Thyroglobulin Blood Test Explained
Learn what a thyroglobulin blood test measures, why it is ordered in thyroid care, how the test works, how to prepare, and how results are interpreted.
Tests are often ordered together as a group. See our hormone test panels guides to understand what common bundles include and why.
Before any hormone test
Some hormone tests are sensitive to time of day, fasting, recent medications, and (for some hormones) the menstrual cycle. Follow the specific preparation instructions from the ordering clinician or laboratory. Our guide to preparing for a hormone test explains the common factors.
Sources
- MedlinePlus (U.S. National Library of Medicine). Lab Tests. https://medlineplus.gov/lab-tests/
- MedlinePlus. How to Understand Your Lab Results. https://medlineplus.gov/lab-tests/how-to-understand-your-lab-results/