Thyroid and Adrenal Health: What Labs Can and Cannot Tell You

The thyroid is a small gland in the front of the neck. It makes two hormones, thyroxine, called T4, and triiodothyronine, called T3. Those hormones affect how the body uses energy, including the heart. The National Institute of Diabetes and Digestive and Kidney Diseases explains that clinicians usually start with a blood test for thyroid-stimulating hormone, or TSH, which comes from the pituitary gland. A high TSH most often means the thyroid is underactive. A low TSH usually means the thyroid is overactive. If TSH is outside the expected range, the next test is often a free T4, and sometimes a T3. Antibody tests help when an autoimmune thyroid condition is suspected. Ultrasound looks at lumps in the gland. A picture of a lump does not, by itself, say whether the gland is making too much hormone or too little.

A thyroid result is a clue that has to be read with the rest of you. Pregnancy, birth control pills, serious illness, steroid medicines, and biotin from supplements can change the numbers. Feeling tired, feeling cold, or seeing a change on the scale can come from thyroid disease and from many other causes. Treating a lab line without that context can miss the actual problem. It can also treat a person who did not need thyroid hormone.

The adrenal glands sit above the kidneys and make cortisol and other hormones. Adrenal fatigue is a phrase used online for tiredness, trouble sleeping, and cravings for salt or sugar, blamed on stress wearing the glands out. The Endocrine Society states that there is no scientific proof that adrenal fatigue is a real diagnosis, and that saliva or blood tests sold to detect it are not supported by good studies. Mayo Clinic says the same: it is not an official diagnosis, and there is no evidence for the idea that everyday stress causes a mild adrenal failure that standard tests miss. Taking that label can delay a real explanation, such as depression, sleep apnea, thyroid disease, or true adrenal insufficiency. Adrenal insufficiency is uncommon. It is diagnosed with standard hormone tests, and sometimes imaging, by a clinician. Hormone supplements taken when you do not need them can suppress your own adrenal glands. Stopping them later can be dangerous.

If you are exhausted, ask for an evaluation. Sleep, meals, and movement often help people feel better while the cause is being sorted out. They are not a substitute for finding a real hormone deficiency when one is present, and they are not a reason to order a panel that cannot answer the question.

Sources

• Thyroid Tests. National Institute of Diabetes and Digestive and Kidney Diseases.
• Adrenal Fatigue. Endocrine Society.
• Adrenal fatigue: What causes it?. Mayo Clinic.

This page is general education, not medical advice. It is not a diagnosis or a treatment plan. Decisions about testing and treatment belong in a visit with your own clinician.