Hypopituitarism

Basics

Description

Hypopituitarism refers to deficiencies of one or more pituitary hormones.

  • “Panhypopituitarism” (pan meaning “all”) technically requires deficiency of all eight pituitary hormones; however, the term is often used for deficiencies of >1 pituitary hormone.

Epidemiology

  • Congenital forms affect both sexes equally and are diagnosed early in childhood.
  • The epidemiology of acquired or secondary forms depends on the underlying cause.

Risk Factors

Genetics

There is increasing understanding of the genetic etiology of familial and/or congenital forms of hypopituitarism. Patterns of inheritance include autosomal recessive, autosomal dominant, X-linked, and digenic forms; can occur in the setting of other complex medical syndromes

Pathophysiology

  • Pathology is based on specific deficiency or deficiencies.
  • Adrenocorticotropic hormone (ACTH): hypocortisolism
  • Thyroid-stimulating hormone (TSH): hypothyroidism
  • Growth hormone (GH): GH deficiency, which can manifest as hypoglycemia in newborns and poor growth in patients >6 to 12 months
  • Luteinizing hormone (LH)/follicle-stimulating hormone (FSH): hypogonadism
  • Antidiuretic hormone (ADH): diabetes insipidus (DI)
  • Note: prolactin (PRL): Hyperprolactinemia can accompany hypothalamic causes of hypopituitarism.

Etiology

  • Idiopathic
  • Congenital
    • Absence of the pituitary (empty sella syndrome is a risk)
    • Pituitary malformations (ectopic posterior pituitary, hypoplastic infundibular stalk, hypoplastic pituitary)
    • Rathke cleft cyst
    • Genetic disorders due to mutations in genes important for CNS development, including transcription factors can be associated with de novo or familial forms (POUF1, HESX1, LHX3, LHX4, OTX2, SOX2, SOX3, PTX2, PROP1, etc.).
    • Antenatal exposures/insults may precipitate.
  • Mechanical
    • Birth trauma or perinatal insult
    • Surgical resection of the gland or damage to the stalk
    • Traumatic brain injury
  • Infiltrative
    • Hypophysitis (inflammation of the pituitary gland)
    • Iron deposition secondary to chronic transfusion therapy (e.g., β-thalassemia)
    • Histiocytosis
    • Sarcoidosis
  • Infection
    • Viral encephalitis
    • Bacterial or fungal infection
    • Tuberculosis
  • Vascular
    • Pituitary infarction
    • Pituitary aneurysm
  • Cranial irradiation
  • Tumors
    • Craniopharyngioma
    • Germinoma
    • Glioma
    • Pinealoma
    • Primitive neuroectodermal tumor (medulloblastoma)

Commonly Associated Conditions

  • Midline defects such as cleft lip/palate, hypotelorism, single central maxillary incisor
  • Septo-optic dysplasia (de Morsier syndrome)
  • Holoprosencephaly

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