Secondary PCOS: Well-defined causes, leading to the PCOS phenotype

Introduction

PCOS has had a complex history punctuated by a constant improvement in its understanding and evolution of diagnostic criteria . These include an awareness of forms of PCOS that are secondary to other endocrinopathies, and therefore the need for them to be recognized in the diagnostic approach to PCOS and, when possible, treated with tailored therapies . The management of secondary forms of PCOS is now possible and also thanks to the availability of increasingly precise, and extensive laboratory support . In this chapter, we describe the well-defined endocrinopathies that lead to secondary forms of PCOS, in particular, hyperprolactinemia, thyroid disorders, nonclassic congenital adrenal hyperplasia due to 21-hydroxylase deficiency (21-NCAH), Cushing's syndrome, acromegaly, and severe insulin resistance states together with the recommended diagnostic approach to differentiate between these forms and PCOS.