What are the causes for anterior pituitary hypofunction?

Answer

Anterior pituitary hypofunction

• Hypothalamic defect
• Pituitary gland defect
  • Tumors
  • Granulomas
  • Vascular necrosis
  • Surgery
  • Radiation
  • Compression by a space occupying lesion

What are the hormones generated from anterior pituitary gland?

Answer

• somatomammotropins
  • growth hormone
  • Prolactin / lactogenic
  • Chorionic somatomamotropin
• Corticotrophin (ACTH)
  • stimulate secretion of glucocorticoid by adrenal cortex
• pituitary glycoprotein hormones
  • thyroid stimulating hormone (TSH)
  • Follicle stimulating hormone (FSH)
    • regulate ovulation and secretion of steroid by ovary
  • Leuteinizing hormone (LH)
    • regulate ovulation and secretion of steroid by ovary

What are the clinical features of  anterior pituitary hypofunction?

Answer

• Growth hormone
  • Short stature
  • Delayed puberty
• ACTH
  • Symptoms of adrenal cortical deficiency
• TSH
  • Symptoms of hypothyroidism
• Gonadotropin
  • Amenorrhea
  • Diminished libido
  • Loss of pubic and axillary hair
  • Atrophy of breast and Testis

What are the steps in evaluating anterior pituitary hypofunction?

Answer

• Establish deficiency of major target organ products
• Differentiate from polyglandular deficiency states 
• Demonstrate absence of compensatory increases of tropic hormones of pituitary
• Establish abnormality in the hypothalamic-pituitary-axis
• Use of stimulation studies
• Use of hypothalamic releasing factors to distinguish between Hypothalamic and pituitary dysfunction

Answer

How do you differentiate hypopituitarism from polyglandular deficiency states ?

Answer

How will you demonstrate absence of compensatory increases of tropic hormones of pituitary?

Answer

How will you establish abnormality in the hypothalamic-pituitary-axis?

Answer

How will you use stimulation studies to help in the localization of lesion?

Answer

How do you stimulate or suppress production of ACTH? How is it useful to distinguish pituitary from hypothalamic problem?

Answer

• ACTH / undetectable in normal basal state
• Deficiency: Stimulation by induced hypoglycemia / of hypothalamus
  • CRF not available for clinical use
  • Hypothalamic problem
    • Positive CRF test
    • Negative response to hypoglycemia
  • Pituitary problem
    • Negative CRF test
    • Negative response to hypoglycemia
• ACTH excess
  • Suppression with dexamethasone

How do you stimulate or suppress production of TSH?

• Deficiency:
  •  TRH stimulation: TSH levels increase up to 15
    • Pituitary problem: Flat response
    • Hypothalamic problem: Normal response
• Excess
  • Flat response to TRH

How do you stimulate or suppress production of gonadotropins?

• Deficiency
  • GnRH stimulation
  • Clomiphere stimulation
    • Hypothalamic dysfunction
      • Normal response to GnRH stimulation
      • Response to Clomiphere stimulation
    • Pituitary dysfunction
      • no response
• Excess

What are the characteristics of prolactin? How do you stimulate or suppress production of prolactin?

Answer

• Prolactin

How do you stimulate or suppress production of growth hormone?

Answer

• Measurable
• Deficiency:
  • stimulation by 
    • hypoglycemia
    • L-dopa
    • GRF
• Excess:
  • suppression by
    • Glucose loading

Describe Hypothalamus.. What are the hormones generated from Hypothalamus?

Answer

• TRH, GnRF, CRF, GRF are releasing hormones
• dopamine inhibits prolactin secretion
  • under neural regulation by variety of neurotransmitters
  • regulated by closed -loop feedback system

How will you  make use of hypothalamic releasing factors to distinguish between Hypothalamic and pituitary dysfunction?

Answer

How do you treat anterior pituitary hypofunction?

Answer

• Replacement of specific hormones
  • Caution in thyroid replacement. Concomitant or preceding replacement of glucocorticoids
• Treat etiology

How does anterior pituitary hyperfunction clinically present?

Answer

• Neurological symptoms (Headache)
• Visual defects (bitemporal hemianopsia)
• Pituitary insufficiency
• Excessive secretion of any of the anterior pituitary hormones
  • Prolactin / Galactorrhea
  • Growth hormone / Acromegaly, Gigantism (in young)
  • ACTH / Cushing's syndrome

How do you diagnose anterior pituitary hyperfunction?

Answer

• Clinical picture
• Excess of the hormone
• Inability to suppress by physiological maneuvers
• MRI and high resolution CT for evaluation of tumor

What are the treatment options for anterior pituitary hyperfunction?

Answer

• Correct deficiencies
• Surgery
• Radiation
• Bromocriptine

Describe posterior pituitary gland.

Answer

• neurohypophysis
• anatomical extension of hypothalamus
• derived from diencephalon
• Located in sella tursica
• in the base of brain

What are the major hormones of posterior pituitary gland?

Answer

• Oxytocin
• Anitdiuretic hormone (ADH) 

What is the function of oxytocin?

Answer

• Oxytocin 
  •  release of breast milk
  •  promote uterine contraction in labor

What is the function of anitdiuretic hormone?

Answer

• Response to serum osmolality, hypovolemia and hypotension
• Normal serum osmolality 285
• Acts on distal nephron to induce an increased water permeability

What happens when there is excess of ADH?

Answer

• Water intoxication. 
• Syndrome of inappropriate ADH secretion

What happens when there is deficiency of ADH?

Answer

• AVP is stored in pituitary but synthesized in the hypothalamus
• Polyuria (>3 L/day) and polydypsia
• Dilute urine (sp gr <1010 or osmolality <300)

How do you distinguish central diabetes insipidus from psychigenic polydypsia?

Answer

• Need to distinguish from psychogenic polydypsia

What is water deprivation test?

Answer

• Water deprivation test followed by pitressin 

What is Nephrogenic diabetes insipidus?

Answer

How do you distinguish central from nephrogenic diabetes insipidus?

Answer

Central vs Nephrogenic 

Is diabetes insipidus is due to hypothalamic or pituitary problem?

Answer

How would you treat diabetes insipidus?

Answer

• Chlorpropamide
• ADH replacement by nasal insufflations