In which condition is increased total T4 and T3 typically observed?

Increased total T4 (thyroxine) and T3 (triiodothyronine) levels are typically observed in primary hyperthyroidism. In this condition, the thyroid gland is overactive and produces excess amounts of thyroid hormones, leading to elevated levels of both T4 and T3 in the bloodstream. Common causes include Graves' disease, toxic nodular goiter, or thyroiditis.

Primary hyperthyroidism results in elevated hormone levels due to intrinsic abnormalities of the thyroid gland itself, which leads to an overproduction of thyroid hormones independent of pituitary stimulation. This contrasts with secondary hyperthyroidism, where the issue lies with the pituitary gland overstimulating the thyroid through increased secretion of thyroid-stimulating hormone (TSH), which may also elevate hormone levels but is specifically associated with a different etiology.

Hypothyroidism and myxedema are characterized by decreased levels of T4 and T3 due to insufficient production from the thyroid gland, not increased levels. Thus, recognizing the unique hormonal dynamics and their pathophysiological implications is crucial in accurately identifying conditions associated with elevated thyroid hormones.