Hypothalamic–pituitary–thyroid axis and TSH receptor antibodies may be the reason for the observation that the relation between free T4 concentration and TSH levels deviates from a pure loglinear relation that has previously been proposed. Standard procedures cover the determination of serum levels of the following hormones: For special conditions the following assays and procedures may be required: Hypothalamic–pituitary–thyroid axis The hypothalamic–pituitary–thyroid axis (HPT axis for short, a.k.a. thyroid homeostasis or thyrotropic feedback control) is part of the neuroendocrine system responsible for the regulation of metabolism. As its name suggests, it depends upon the hypothalamus, the pituitary gland, and the thyroid gland. The
Pituitary adenoma interacting protein" ("AIP") gene , and duplications in chromosome Xq26.3 that include the "GPR101" gene that also causes X-linked acrogigantism (X-LAG) syndrome. About 15-20% of FIPA families carry a germline "AIP" gene mutation or deletion, and the disease occurs as autosomal dominant with incomplete penetrance, meaning that about 20% of AIP mutation carriers will develop a pituitary adenoma. "AIP" mutation associated pituitary adenomas (either presenting as FIPA or as individual, non familial cases) are usually growth hormone secreting (acromegaly) or prolactin secreting (prolactinoma) adenomas that are large (macroadenomas) and often occur in children, adolescents and young adults. Daly and colleagues