Hyperpituitarism

Hyperpituitarism causes two categories of symptoms: some caused by abnormal hormone secretion and others induced by the tumor itself. The latter consist of headaches and visual impairment, caused by optic nerve compression, or even hypopituitarism. If prolactin hypersecretion occurs in a pubertal girl, she will present with pubertal arrest. Galactorrhea may also be present in this case. Pubertal boys and prepubertal children complain about growth failure, visual impairment, and headaches, but the first category also experiences pubertal arrest [1]. Medical history and physical examination reveal menstrual abnormalities, acanthosis nigricans, and gynecomastia, in addition to other traits of the disease the patients notice.

Excess growth hormone causes acromegaly in adults and gigantism in children. Gigantism presents as accelerated complete growth in children, whereas acromegaly is characterized by the growth of the extremities (fingers and toes) and facial coarsening [2], as well as occlusion changes and apertognathia [3] [4]. Additional features include macrocephaly, prognathism, frontal bossing, irregular menses in women, and hyperhidrosis. The distance between teeth increases and the lips become thicker and darker [5]. In adult patients, cardiac hypertrophy sets in during the progression of the disease. Uterine, prostate, and colon benign tumors seem to have an increased incidence in these patients. The physician must also keep in mind the fact that these patients are prone to develop diabetes mellitus and peripheral neuropathies, as well as muscular and articular disorders, and conduct an active surveillance in this area [6] [7].

If the adrenocorticotropic hormone (ACTH) is involved, patient present with symptoms of excessive glucocorticoid secretion: hypertension, hirsutism, weight gain, acne, fatigability, and sleep apnea signs [8]. The clinician is often able to highlight the presence of the typical Cushing facies, as well as a dorsal cervical fat pad and bruising.

Hyperpituitarism workup should concentrate on detecting abnormal pituitary gland function based on whatever clinical findings the physician encounters. For instance, if hyperprolactinemia is suspected, serum prolactin should be measured several times if the obtained values are normal, but one determination is sufficient if a value above 200 ng/mL is found. A thyrotropin-releasing hormone (TRH) stimulation test can also be performed if a doubt exists, given that intravenous administration of TRH leads to an abrupt increase of prolactinemia 15 to 30 minutes later in normal individuals. Prolactinoma patients usually do not show this increase in prolactin serum levels.

A patient with an adrenocorticotropic hormone (ACTH) - releasing adenoma should undergo a urinary free cortisol excretion measurement, as well as a plasma cortisol determination. The first test accurately measures the cortisol secretion rate, while the second one needs to be interpreted based on the time the blood sample was drawn, keeping in mind that cortisol levels are normally highest from 6 to 8 AM and decline during the day. The lack of variation suggests Cushing disease. Additional investigations include the dexamethasone suppression testing and the corticotropin-releasing hormone (CRH) stimulation testing in uncertain cases.

When growth hormone oversecretion is suspected, the following tests should be ordered: serum insulin-like growth factor-I (IGF-I) measurement, serum insulin-like growth factor-binding protein-3 (IGFBP-3) dosage, and an oral glucose tolerance test (OGTT). After 1.75-g/kg oral glucose ingestion (maximum 75g), the serum growth hormone level should decrease to less than 5 ng/dL within 3 hours in healthy individuals.

The presence of the pituitary adenoma itself may be revealed by magnetic resonance imaging (MRI) with gadolinium administration, what is considered to be the gold standard [9] [10].

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