This claim suggests that checking a specific thyroid hormone called rT3 in the blood could help doctors better understand mood and thinking problems. Adding this test to regular thyroid checks might lead to more accurate diagnoses and treatments tailored to how a patient's body processes hormones.

People with certain mental health conditions like depression, bipolar disorder, and schizophrenia often have different thyroid hormone levels in their blood compared to healthy people. Specifically, they tend to have higher levels of a hormone called rT3 and a lower ratio of T3 to rT3. This pattern suggests that these different brain conditions might share the same underlying metabolic issue.

For people with mental health conditions, having higher levels of a specific thyroid hormone byproduct and a lower ratio of active thyroid hormones seems to go hand-in-hand with worse symptoms and less response to usual psychiatric medications. This suggests that how the body processes thyroid hormones might play a direct role in how severe the condition is and how well treatments work.

A substance called rT3 blocks your body's active thyroid hormones from working properly by taking their place on cellular receptors. This prevents your cells from getting the energy signals they need, which ultimately slows down your metabolism.

A thyroid hormone byproduct called rT3 might block the active thyroid hormone from working properly in your brain cells. This blockage could lower the hormone's effectiveness, which might play a role in causing certain mental health and brain development issues.

When your body is under severe stress or you take certain medications like amiodarone, your thyroid hormone levels change in a way that can confuse standard blood tests. This means doctors need to look at the bigger picture before diagnosing thyroid problems.