[Molecular forms of pituitary and plasma ACTH in physiology and pathology].

Immunoreactive ACTH has been found in human pituitary and plasma under different molecular forms: Big ACTH, intermediate ACTH, ACTH 1-39 and fragments of ACTH. In the literature, there are some controversies especially regarding to the importance of Big ACTH in plasma and tissue. Big ACTH is absent or present in only low amounts in plasma and pituitary extracts from normal subjects. However, the proportion of Big ACTH is very high in tumor extracts and plasma obtained from patients with ectopic ACTH syndrome High concentrations of small ACTH fragments are also present in this syndrome.