Secretory tumors of the pituitary gland: a clinical biochemistry perspective

The pituitary gland is responsible for the production and/or secretion of various hormones that play a vital role in regulating endocrine function within the body. Secretory tumors of the anterior pituitary predominantly, pituitary adenomas, collectively account for 10%-25% of central nervous system tumors requiring surgical treatment. The most common secretory tumors are prolactinomas, which can be diagnosed by basal prolactin levels. Acromegaly can be diagnosed by basal insulin growth-like factor 1 levels and the failure of growth hormone (GH) to suppress during an oral glucose tolerance test. Cushing disease can be diagnosed by demonstrating hypercortisolemia evidenced by increased salivary cortisol levels in the evening, increased urine free cortisol excretion and failure of plasma cortisol to suppress following oral dexamethasone given overnight (1.0 mg). We also discuss the diagnosis of the rarer thyroid-stimulating hormone and gonadotrophin secretory tumors. Morbidity is associated with tumor occurrence, clinical sequelae as well as the related medical, surgical and radiological management. This review focuses on the pathogenesis of secretory tumors of the anterior pituitary with emphasis on molecular mechanisms associated with tumorigenesis and the major role of the clinical chemistry laboratory in diagnosis and management of these tumors.