If someone has an underactive thyroid and signs of an overactive immune system — especially bulging eyes — doctors should still think about Graves’ disease, even if the thyroid isn’t overactive.

Sometimes people with Graves’ disease get eye or skin problems even when their thyroid hormone levels are normal, which suggests these issues might be caused by the immune system attacking tissues directly, not just from too much thyroid hormone.

Sometimes people can have Graves’ disease and show symptoms like bulging eyes or skin issues even if their thyroid isn’t overactive—this can happen if their thyroid doesn’t work well enough to produce excess hormones, and it means doctors might miss the disease if they only check thyroid levels.

In Graves' disease, the body's immune system accidentally attacks the thyroid by making antibodies that turn it on too much, causing it to overproduce hormones and leading to a condition called hyperthyroidism.

A young adult had sudden psychosis — like hearing voices and mood changes — and it turned out to be the first sign of an overactive thyroid caused by an immune system problem. This shows that sometimes, mental health symptoms can actually be caused by a physical illness.

When someone has Graves’ disease, their thyroid hormones get too high, which tells the brain to stop making a hormone that stimulates the thyroid — so that hormone ends up being very low or even missing in blood tests.