Posterior pituitary hyperfunction disorders Flashcards
what causes Syndrome of inappropriate ADH (SiADH)?
- Small cell carcinoma lung****
Most common cause
- Central nervous system disease (injury, tumor etc.)
- Drugs:
- Chlorpropamide, an oral sulfonylurea
- Lung infection (tuberculosis)
what are the 3 Effects of excess ADH?
- ADH acts on the distal tubules and collecting ducts to promote excessive water retention
- Hyponatremia
- Urine osmolarity > serum osmolarity
Clinical findings based on retention of free water in SIADH?
- Hyponatremia
- Low serum osmolality
- Mental status changes
what is the diagnostic criteria for SIADH?
- Hyponatremia (serum Na usually
- Plasma hypo-osmolality
- Increased urine sodium concentration
- Euvolemia ( edema absent)
what is the treatment for SIADH?
Demeclocycline
Pituitary hypofunction (Hypopituitarism) can be of 2 types?
- Anterior pituitary hypofunction
- Posterior pituitary hypofunction
what is Anterior pituitary hypofunction?
Refers to partial or complete loss of anterior pituitary function.
what can cause Anterior pituitary hypofunction?
- Non-functioning (null) pituitary adenomas**
- Sheehan’s post partum pituitary necrosis**
- Craniopharyngioma: (children)**
- Pituitary apoplexy**
- Empty Sella syndrome
- Ablation of pituitary by surgery or radiation
what is MCC of hypopituitarism in adults**?
what is it associated with?
Nonfunctioning pituitary adenoma
multiple endocrine neoplasia (MEN) I syndrome*.
what are the Clinical findings for Nonfunctioning pituitary adenoma?
The adenoma expands causing:
- Loss of anterior pituitary parenchyma resulting in loss of trophic hormones and hypofunction of target organs.
- Enlarged sella turcica
- Headache, visual field defects (bitemporal hemianopsia- due to compression of optic chiasm), diplopia (due to oculomotor nerve palsies).
what is Sheehan’s postpartum pituitary necrosis?
Pregnancy related infarction of the pituitary gland.
- Pituitary doubles in size during pregnancy but blood supply does not increase sufficiently.
- Hypovolemic shock resulting from postpartum hemorrhage causes infarction of pituitary gland.
how does sheehan’s postpartum pituitary necrosis present?
- Sudden cessation of lactation due to loss of prolactin
- Loss of pubic hair and fatigue
- Eventual development of panhypopituitarism.
what is the most common cause of hypopituitarism in children?
from where does it come from?
where can it be located?
Craniopharyngioma (adamantinoma)
rathke’s pouch
above the sella turcica
symptoms of craniopharyngioma?
- Headache
- endocrine deficiency,
- visual disturbances
- central diabetes insipidus
how does craniopharangioma look on micro and gross?
- Cystic tumor filled with fluid = machinery oil
- Shows areas of calcification
- Stratified squamous cells, keratinized
identify the parts of a micro photo of a craniopharyngeoma
upper left: calcification
lower right: keratinized squamous cells
magnification: cholesterol crystals
what is Pituitary apoplexy?
what is Empty sella syndrome?
Sudden enlargement of a pituitary adenoma due to bleeding within the adenoma
Refers to abscense of the pituitary due to compression and atrophy or surgical removal.
decreased gonadotropins in hypopituitarism will cause what effects on adult women, men, children?
and how will these changes reflect in a lab report?
adult woman = 2ry amenorrhea, decreased libido, diminished 2ry sex characteristics
adult men = impotence, diminished 2ry sex characteristis
children = growth and sexual maturation retardation (delayed fusion of epiphyses)
labs: low FSH and LH, low estradiol/testosterone
growth hormone deficiency found in hypopituitarism will affect adults and children how?
adults = only hypoglycemia
children = pituitarism dwarf, delayed growth and sexual maturation
TSH deficiencty found in hypopituitarism will affect individuals how?
ACTH deficiency found in hypopituitarism will affect individuals how?
Prolactin deficiency found in hypopituitarism will affect individuals how?
- Secondary hypothyroidism
- Decreased serum T4 and TSH
- Secondary adrenal insufficiency
- Hypoglycemia (cortisol is gluconeogenic)
- Failure of lactation in post-partum patients
what are the most important hormonal deficiencies to recognize in hypopituitarism?
- Adrenal insufficiency
- Hypothyrodism
adrenal insufficiency and hypothyroidism should be treated with?
Glucocorticoids first (to avoid adrenal crisis) and then with Thyroid hormone
Name a Posterior pituitary hypofunction disease
Diabetes insipidus
what is Diabetes insipidus?
Condition that results due to Deficiency of ADH
or Failure of the kidney to respond to ADH causing
passage of large volumes of dilute urine
what are the 2 types of diabetes insipidus?
how do we differentiate each?
Central diabetes insipidus: Deficiency of ADH
Nephrogenic diabetes insipidus: Failure of the kidney to respond to ADH
what can cause central diabetes insipidus?
- Transection of pituitary stalk (e.g. trauma)
- Hypothalamic disease (e.g. histiocytosis X and sarcoidosis)
- Posterior pituitary disease (e.g. metastasis)
- Pituitary surgery
what are the causes of nephrogenic diabetes insipidus?
- Hypokalemia: vacuolar nephropathy of Collecting tubules
- Drugs: Lithium, demeclocycline
- Nephrocalcinosis: calcification of BM of collecting tubule
Clinical features o fdiabetes insipidus are based on what?
What are the clinical features of diabetes insipidus?
water loss
- Polyuria, polydipsia with risk of life threatening dehydration.
- Hypernatremia and high serum osmolality
- Low urine osmolality and specific gravity.
How to Distinguish CDI from NDI?
Look for response to exogenous administration of ADH
Concentrated urine –> Central DI
No effect –> Nephrogenic DI
