The pituitary gland controls the function of other endocrine organs.
The anterior pituitary gland produces the hormones: thyrotropin (thyroid-stimulating hormone [TSH]), corticotropin (adrenocorticotropic hormone [ACTH]), luteinizing hormone (LH), follicle-stimulating hormone (FSH), growth hormone (GH), and prolactin (PRL).
The anterior pituitary is controlled by hypothalamic-releasing hormones.
The posterior pituitary produces vasopressin (antidiuretic hormone [ADH]) and oxytocin.
Panhypopituitarism is a condition of inadequate or absent production of the anterior pituitary hormones.
Results from the deficiency of trophic hormones caused by destructive processes, including ischemia, surgery, radiation and inflammatory reactions.
Nonfunctional pituitary adenomas may destroy adjacent pituitary tissue and be responsible for this process.
Target endocrine gland failure secondary to insufficient hypothalamic or pituitary hormone stimulation of the target gland or tissue.
Related to secondary adrenal insufficiency, secondary hypothyroidism, secondary gonad failure, deficiency of growth hormone, and or diabetes mellitus alone or in combination.
Loss of all pituitary function is ref2242ed to as panhypopituitarism, while loss of one or more pituitary hormones is ref2242ed to as partial hypopituitarism.
Most common cause is a lesion on the pituitary: pituitary adenoma, craniopharyngioma, Rathke’s cleft cyst lymphocytic infiltration, hypophysitis, acidosis, and metastatic tumor.
Larger pituitary lesions associated with more permanent loss of pituitary function.
Pituitary function may improve after the selective removal of a pituitary adenoma.
May be a result of whole brain radiation, pituitary radiation and head and neck cancer radiation.
Head trauma may lead to this process and may be seen in as many as 36% of individuals.
Hypothalamic developmental abnormalities may be associated with this process.
The effects of hypopituitarism in children dependon the specific defect: GH deficiency can result in hypoglycemia and short stature.
Gonadotropin deficiency can to prenatal micropenis and delayed puberty in older children.
Corticotropin deficiency interferes with normal carbohydrate, protein, and lipid metabolism and may result in weight loss, hypoglycemia, fatigue, hypotension, and even death.
Thyrotropin deficiency leads to hypothyroidism.
Morbidity and mortality related to hypopituitarism are caused by the individual hormone deficiencies or the underlying cause of hypopituitarism.
Acute mortality due to hormonal deficiencies is rare event , but when deaths occur due to hormonal deficiencies, they are usually caused by adrenal insufficiency secondary to ACTH deficiency.
Childhood hypopituitarism may be associated with a shortened adult lifespan, due to cardiovascular abnormalities.
GH deficiency is associated with dyslipidemia.
Hypopituitarism in children is suspected with midline defects or optic atrophy, and in boys with micropenis.
Infants with hypopituitarism may develop hypoglycemia, hypernatremic dehydration due to diabetes insipidus, growth retardation, dry skin, fatigue, constipation, nausea,vomiting and malaise.
Pituitary function should be evaluated in children with craniopharyngiomas or other hypothalamic or pituitary tumors or have received cranial irradiation.
Older children may present because of altered puberty and girls may have primary or secondary amenorrhea.
Polyuria and polydipsia due to central diabetes insipidus may also be a presenting symptom.
ACTH deficient patients may present with hyponatremia.
diagnosis requires hormonal studies of target gland and their respective stimulatory pituitary hormone.
Testing includes:
ACTH (Cortrosyn) stimulation test (or morning cortisol and ACTH)
TSH and thyroxine
FSH, LH, and either estradiol (if amenorrheic) or morning testosterone (as appropriate for sex)
Prolactin
GH testing