Primary, Secondary, Tertiary Disorders
1ƒ - Involve the organs that produce the hormone (e.g. primary hypothyroidism results from an underactive thyroid gland and T4 reduction.
2ƒ - Related to pituitary that produces trophic hormones (e.g. sec. hypothyroidism due to an underactive anterior pituitary, which secondarily _ thyroid function owing to TSH _)
3ƒ - Hypothalamic problems (e.g. tertiary hypothyroidism due to reduced release of TRH which _TSH which reduces synthesis of T4.