Hypopituitarism
Hypopituitarism
- As part of this process, we can evaluate hormone levels (or use stimulation tests for GH and ACTH), and use brain imaging to look for pituitary tumors, etc.
Anatomy Review
- Hypothalamus, pituitary stalk, and the anterior and posterior pituitary lobes.
Causes of Hypopituitarism
- Pituitary Adenoma: The most common cause in this category is pituitary adenoma; we show a tumor invading the space around the gland and compressing the anterior lobe where it sits in the sella turcica.
- Pituitary apoplexy, which is associated with adenomas, can cause infarction or hemorrhaging, which further impairs hormone production.
- Craniopharyngiomas are a cause of invasive and compressive hypopituitarism in children, in whom we see disturbed growth from the loss of growth hormone.
- Risk factors for empty sella syndrome include female sex and hypertension.
- Hypopituitarism may be evident soon after birth, or later, in the form of low blood pressure, vision deficits, the inability to lactate or menstruate, or other deficiencies.
- Two examples include sarcoidosis (neurosarcoidosis, esp. of the pituitary stalk), and Langerhans histiocytosis (which is associated with posterior pituitary involvement and diabetes insipidus).
- Two examples of this:
- Combined hormone deficiencies include mutations in POU1F1, PROP-1, HESX1, and PITX2.
- Isolated hormonal deficiencies have also been associated with specific mutations (for example, recall that defects in the TRH receptor can lead to TSH deficiencies).
Signs and Symptoms of Hormone Deficiency
- Deficiencies in children produce slowed growth.
- Adults may experience a vague sense of lowered well-being with lethargy and loss of interest; more specific signs include a shift in body composition with decreased muscle mass and increased fat, hyperlipidemia, insulin resistance, and cardiovascular effects including endothelial dysfunction and reduced cardiac output.
- Indicate that the effects of reduced luteinizing hormone and follicle stimulating hormone may be particularly subtle, but when the deficiency is extreme, patients can experience amenorrhea, erectile dysfunction, and infertility.
- Kallman Syndrome is a genetic absence of GnRH receptors leading to LH/FSH deficiency – this is an example of a genetic etiology for a specific hormonal deficiency.
- Lack of thyroid stimulating hormone produces hypothyroidism without the goiter.
- Symptoms are usually less severe than in primary hypothyroidism, but still include cold intolerance, fatigue, weight gain, muscle/joint pain, constipation, and bradycardia.
- ACTH deficiency and adrenal insufficiency can cause serious problems due to loss of glucocorticoid actions, including fatigue, hypotension, increased risk of infections, and hypoglycemia.
- These effects are usually worse when the patient experiences stress - recall that cortisol is released in response to stress, but is lacking in these patients.
- Mineralocorticoid levels (aldosterone) are often preserved, since they are primarily maintained by the renin-angiotensin-aldosterone system.
- Prolactin deficiency is most obvious when lactation is deficient.
- Antidiuretic hormone (aka, vasopressin) can be deficient when the posterior pituitary is involved – recall that ADH deficiency causes diabetes insipidus, in which the kidneys produce large volumes of hypo-osmolar urine. Patients are hypovolemic and dehydrated.
- For references, please see the full tutorial on Hypopituitarism.