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For further information, see CMDT Part 26-05: Nonfunctioning Pituitary Adenomas

Key Features

Essentials of Diagnosis

  • Clinical and biochemical evaluation for pituitary hormone hypersecretion is negative

  • MRI shows a pituitary microadenoma (<1 cm diameter) or macroadenoma (≥ 1 cm diameter)

  • Headache, visual field compromise and anterior hypopituitarism are common with macroadenomas

  • Elevated serum PRL with macroadenomas may be due to stalk compression

General Considerations

  • Benign neuroendocrine neoplasms that do not produce symptoms from hormone oversecretion

  • Nonfunctioning pituitary microadenomas (< 1 cm) are common, detected as an incidental finding in 4–37% of brain CT or MR imaging

  • Account for up to 14–54% of all pituitary adenomas and are more frequent with advancing age

Clinical Findings

Symptoms and Signs

  • Nonfunctioning pituitary macroadenomas

    • Measure 1 cm or larger

    • Tend to be more aggressive than functioning pituitary adenomas

    • Frequently present with mass effect symptoms, including

      • Headache

      • Visual field compromise

      • Cranial nerve palsies affecting extraocular muscles

      • Pituitary apoplexy

  • Larger macroadenomas frequently cause some hypopituitarism, particularly hypogonadotropic hypogonadism

  • Nonfunctioning pituitary microadenomas are asymptomatic

Differential Diagnosis

  • Pituitary craniopharyngiomas

  • Gliomas

  • Meningiomas

  • Skull base osteosarcomas

  • Rathke cysts

  • Lymphocytic hypophysitis

  • Infection

  • Metastases

Diagnosis

Laboratory Findings

  • All patients with a pituitary adenoma require testing for pituitary hormone hypersecretion

    • A serum PRL is obtained to screen for prolactin hypersecretion

    • Women with hyperprolactinemia are tested for pregnancy with a serum hCG.

    • Clinical suspicion should dictate whether to formally test for Cushing disease or acromegaly

  • Pituitary macroadenomas

    • All patients require evaluation for anterior hypopituitarism

    • Serum free T4, thyroid-stimulating hormone (TSH), morning serum testosterone and free testosterone (men)

    • Serum luteinizing hormone (LH) and follicle-stimulating hormone (FSH) (men with low serum testosterone, women who are postmenopausal, and younger women with amenorrhea)

    • Serum sodium and glucose

    • A serum IGF-I is drawn to screen for growth hormone (GH) deficiency

    • Younger patients with short stature who have not fused their epiphyses should have a full evaluation for growth hormone deficiency

    • Patients with a macroadenoma that impinges upon the optic chiasm require formal visual field testing

    • A cosyntropin stimulation test is performed for patients with hyponatremia or symptoms of possible hypoadrenalism

Imaging

  • Pituitary dynamic contrast-enhanced MRI (3T)

    • Modality of choice for the evaluation and follow-up of pituitary adenomas

    • About 10% of nonfunctioning pituitary microadenomas enlarge over several years, whereas 23% of pituitary nonfunctioning macroadenomas enlarge significantly

    • Nonfunctioning pituitary microadenomas that are < 5 mm require no further MRI follow-up

    • For nonfunctioning pituitary adenomas ≥ 5 mm, repeat MRI is recommended at 6 months then yearly for 3 years

    • If no enlargement is noted, MRI surveillance can be done less frequently

Treatment

  • No treatment needed for ...

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