Hypopituitarism; Defination, Causes, Symptoms, Diagnosis, Treatment, Complication, Preventions

Hypopituitarism is the decreased (hypo) secretion of one or more of the eight hormones normally produced by the pituitary gland at the base of the brain. If there is decreased secretion of one specific pituitary hormone, the condition is known as selective hypopituitarism. If there is decreased secretion of most or all pituitary hormones

Causes of Hypopituitarism

  • Grave disease
    • Mechanism: thyroid-stimulating antibodies
    • Female > Male (10x)
    • Findings: ophthalmopathy (lid lag), infiltrative dermopathy (pretibial)
  • Toxic adenoma, toxic multinodular goiter
    • Mechanism: Excess thyroid hormone production
  • Thyroiditis
    • Mechanism: inflammation results in increased thyroid hormone release, typically followed by depletion and TSH suppression resulting in hypothyroidism
    • Signs/symptoms: tachycardia, weight loss, irritability, sweating, anxiety, heat intolerance
    • Subacute thyroiditis
      • Post-viral
      • Symptoms: hoarseness, dysphagia, painful thyroid
    • Hashimoto
      • Typically hypothyroidism
    • Drug-induced: Lithium, amiodarone
    • Trauma: surgical, direct
  • Additional Causes
Type Causes
Tumors Most cases of hypopituitarism are due to pituitary adenomas compressing the normal tissue in the gland, and rarely other brain tumors outside the gland—craniopharyngioma, meningioma, chordoma, ependymoma, glioma or metastasis from cancer elsewhere in the body.
Infection,
inflammation and
infiltration
The pituitary may also be affected by infections of the brain (brain abscess, meningitisencephalitis) or of the gland itself, or it may be infiltrated by abnormal cells (neurosarcoidosis, histiocytosis) or excessive iron (hemochromatosis). Empty sella syndrome is unexplained disappearance of pituitary tissue, probably due to outside pressure. Autoimmune or lymphocytic hypophysitis occurs when the immune system directly attacks the pituitary.
Vascular As a pregnancy comes to term, a pregnant woman’s pituitary gland is vulnerable to low blood pressure, such as may result from hemorrhage; pituitary damage due to bleeding after childbirth is called Sheehan’s syndrome. Pituitary apoplexy is hemorrhage or infarction (loss of blood supply) of the pituitary. Other forms of stroke are increasingly recognized as a cause for hypopituitarism.
Radiation Radiation-induced hypopituitarism mainly affects growth hormone and gonadal hormones.[14] In contrast, adrenocorticotrophic hormone (ACTH) and thyroid stimulating hormone (TSH) deficiencies are the least common among people with radiation-induced hypopituitarism.[14] Changes in prolactin-secretion is usually mild, and vasopressin deficiency appears to be very rare as a consequence of radiation.
Other physical External physical causes for hypopituitarism include traumatic brain injury, subarachnoid hemorrhage, neurosurgery and ionizing radiation (e.g. radiation therapy for a previous brain tumor). Bites from Russell’s vipers have also been known to cause hypopituitarism in approx 29% of cases
Congenital Congenital hypopituitarism (present at birth) may be the result of complications around delivery, or may be the result of insufficient development (hypoplasia) of the gland, sometimes in the context of specific genetic abnormalities. Mutations may cause either insufficient development of the gland or decreased function. Forms of combined pituitary hormone deficiency (“CPHD”) include:

Type OMIM Gene
CPHD1 613038 POU1F1
CPHD2 262600 PROP1
CPHD3 600577 LHX3
CPHD4 602146 LHX4
CPHD5 (Septo-optic dysplasia) 182230 HESX1

Kallmann syndrome causes deficiency of the gonadotropins only. Bardet-Biedl syndrome and Prader-Willi syndrome have been associated with pituitary hormone deficiencies.

Symptoms of Hypopituitarism

  •  Adenoma
    • Symtoms/Signs
  • Ischemic necrosis
    • Sickle cell disease, vasculitis, cavernous sinus thrombosis, infection, TBI, post-partum (Sheehan)
  • Pituitary apoplexy
    • Acute loss of pituitary function from infection/hemorrhage, rarely tumor
    • Symptoms/Signs
Constitutional Weight loss, heat intolerance, perspiration
Cardiopulmonary Palpitations, chest pain, dyspnea
Neuropsychiatric Tremor, anxiety, double vision, muscle weakness
Neck Fullness, dysphagia, dysphonia
Musculoskeletal Extremity swelling
Reproductive Irregular menses, decreased libido, gynecomastia

 

Signs

Vital signs Tachycardia, widened pulse pressure, fever
Cardiovascular Hyperdynamic precordium, CHF, atrial fibrillation, systolic flow murmur
Ophthalmologic Widened palpebral fissure, periorbital edema, proptosis, diplopia, restricted superior gaze
Neurologic Tremor, hyperreflexia, proximal muscle weakness
Dermatologic Palmar erythema, hyperpigmented plaques or non-pitting edema of tibia
Neck Enlarged or nodular thyroid

Treatment of Hypopituitarism

Treatment of hypopituitarism is threefold removing the underlying cause, treating the hormone deficiencies, and addressing any other repercussions that arise from the hormone deficiencies.

Prolactinomas may respond to dopamine agonist treatment–medication that mimics the action of dopamine on the lactrotrope cells, usually bromocriptine or cabergoline. This approach may improve pituitary hormone secretion in more than half the cases, and make supplementary treatment unnecessary.

Other specific underlying causes are treated as normally. For example, hemochromatosis is treated by venesection, the regular removal of a fixed amount of blood. Eventually, this decreases the iron levels in the body and improves the function of the organs in which iron has accumulated.

Hormone replacement

Most pituitary hormones can be replaced indirectly by administering the products of the effector glands: hydrocortisone (cortisol) for adrenal insufficiency, levothyroxine for hypothyroidism, testosterone for male hypogonadism, and estradiol for female hypogonadism (usually with a progestogen to inhibit unwanted effects on the uterus). Growth hormone is available in synthetic form, but needs to be administered parenterally (by injection). Antidiuretic hormone can be replaced by desmopressin (DDAVP) tablets or nose spray. Generally, the lowest dose of the replacement medication is used to restore wellbeing and correct the deranged results, as excessive doses would cause side-effects or complications.Those requiring hydrocortisone are usually instructed to increase their dose in physically stressful events such as injury, hospitalization and dental work as these are times when the normal supplementary dose may be inadequate, putting the patient at risk of adrenal crisis.

Long-term follow up by specialists in endocrinology is generally needed for people with known hypopituitarism. Apart from ensuring the right treatment is being used and at the right doses, this also provides an opportunity to deal with new symptoms and to address complications of treatment.

Difficult situations arise in deficiencies of the hypothalamus-pituitary-gonadal axis in people (both men and women) who experience infertility; infertility in hypopituitarism may be treated with subcutaneous infusions of FSH, human chorionic gonadotropin–which mimics the action of LH–and occasionally GnRH.

Complications

Several hormone deficiencies associated with hypopituitarism may lead to secondary diseases. For instance, growth hormone deficiency is associated with obesity, raised cholesterol and the metabolic syndrome, and estradiol deficiency may lead to osteoporosis. While effective treatment of the underlying hormone deficiencies may improve these risks, it is often necessary to treat them directly

References

  1.  Hypopituitarism” at Dorland’s Medical Dictionary
  2.  Ignatavicius, Donna; Workman, Linda (2015). Medical-Surgical Nursing: Patient-Centered Collaborative Care (8 ed.). Saunders. pp. 1266–67. ISBN 9781455772551.
  3.  Panhypopituitarism” at Dorland’s Medical Dictionary
  4.  synd/2008 at Who Named It?
  5. Simmonds disease” at Dorland’s Medical Dictionary
  6. Yalow RS, Berson SA (July 1960). “Immunoassay of endogenous plasma insulin in man”J. Clin. Invest39 (7): 1157–75. doi:10.1172/JCI104130PMC 441860PMID 13846364.
  7. Harsoulis P, Marshall JC, Kuku SF, Burke CW, London DR, Fraser TR (November 1973). “Combined test for assessment of anterior pituitary function”Br Med J4 (5888): 326–29. doi:10.1136/bmj.4.5888.326PMC 1587416PMID 4202260.
  8.  Fernandez A, Brada M, Zabuliene L, Karavitaki N, Wass JA (September 2009). “Radiation-induced hypopituitarism”. Endocr. Relat. Cancer16 (3): 733–72. doi:10.1677/ERC-08-0231PMID 19498038.
  9. Cohen LE, Radovick S (August 2002). “Molecular basis of combined pituitary hormone deficiencies”. Endocr. Rev23 (4): 431–42. doi:10.1210/er.2001-0030PMID 12202459.
  10.  Kelberman D, Dattani MT (August 2007). “Hypothalamic and pituitary development: novel insights into the aetiology”. Eur. J. Endocrinol. 157 Suppl 1: S3–14. doi:10.1530/EJE-07-0156PMID 17785694.
  11.  Guillemin R (January 2005). “Hypothalamic hormones a.k.a. hypothalamic releasing factors”. J. Endocrinol184 (1): 11–28. doi:10.1677/joe.1.05883PMID 15642779.
  12. Arafah BM, Nasrallah MP (December 2001). “Pituitary tumors: pathophysiology, clinical manifestations and management”. Endocr. Relat. Cancer8 (4): 287–305. doi:10.1677/erc.0.0080287PMID 11733226.
  13. Kaushal K, Shalet SM (2007). “Defining growth hormone status in adults with hypopituitarism”. Horm. Res68 (4): 185–94. doi:10.1159/000101286PMID 17389809.
  14.  Dorin RI, Qualls CR, Crapo LM (2003). “Diagnosis of adrenal insufficiency”. Ann. Intern. Med139 (3): 194–204. doi:10.7326/0003-4819-139-3-200308050-00017PMID 12899587.

Hypopituitarism

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