Autoimmune hypophysitis is defined as inflammation of the pituitary gland due to autoimmunity. Signs and symptoms
Autoimmune hypophysitis can lead to deficiencies in one or more pituitary hormones, causing central diabetes insipidus if the posterior pituitary gland is affected as well as central adrenal insufficiency and central hypothyroidism if the anterior pituitary gland is affected. The symptoms depend on what part of the pituitary is affected. Lymphocytic adenohypophysitis (LAH) occurs when the anterior pituitary cells are affected by autoimmune inflammation resulting in either no symptoms, adrenal insufficiency (if the ACTH producing cells are affected), hypothyroidism (if the TSH producing cells are damaged), or hypogonadism (if the LH and/or FSH producing cells are involved). In some cases, the presence of inflammation within the pituitary gland leads to interruption of dopamine flow from the hypothalamus into the pituitary causing high levels of the hormone prolactin and, often as a consequence, milk production from the breasts (in older girls and women). Lymphocytic Infundibuloneurohypophysitis (LINH) occurs when the posterior pituitary is affected resulting in diabetes insipidus. Both LAH and LINH may also lead to symptoms of an intracranial mass such as headache or disturbance of vision, i.e. bitemporal hemianopia. The pituitary produces multiple hormones relating to various metabolic functions. Sufficiently low production of certain pituitary hormones can be fatal resulting in the failure of the thyroid or adrenal glands. Common symptoms include nausea, vomiting, fatigue, loss of libido, amenorrhea, and dizziness. It is estimated that, typically, it takes from 12 to 40 years for autoimmune destruction to present symptoms.
Biopsy of the pituitary gland is not easily performed with safety as it sits under the brain, however, a test does exist to detect antibodies to the pituitary without biopsy: autoantibodies to M(r) 49,000 pituitary cytosolic protein may represent markers for an immunological process affecting the pituitary gland. Tests for normal pituitary gland hormone production tend to be expensive and in some cases difficult to administer. In addition, certain hormone levels vary largely throughout the day and in response to metabolic factors, making abnormal levels difficult to calibrate—further hampering diagnosis. Assessment for other autoimmune and inflammatory diseases should also be performed by obtaining complete blood count, complete metabolic panel, c-reactive protein, erythrocyte sedimentation rate, antinuclear antibody, and lupus antibodies at the very least. Gadolinium-enhanced MRI of the pituitary is the imagining of choice as well, and it is important to distinguish lymphocytic hypophysitis from a pituitary adenoma. Treatment
Inflammation resolves usually after several months of glucocorticoid treatment For those that show no improvement with corticosteroids or have relapsed after treatment with corticosteroids, immunosuppressive medications such as methotrexate, azathioprine, and cyclosporine can be used as well. There have also been some cases where dopamine agonists such as cabergoline/bromocriptine have also been successfully used in those with hyperprolactinemia due to pituitary inflammation. Surgery is only an option for those suffering from visual problems/ophthalmoplegia, have a mass like an effect from compression of nearby structures, or for those that require histology for diagnosis. Epidemiology
A large scale study on cadavers done in Sweden, performed biopsies on hundreds of pituitary glands.