Posterior Pituitary- Hypo/hypernatremia

Question 1

Diabetes means

Answer 1

urinating too much

Question 2

What is Central Diabetes Insipidus

Answer 2

Lack of ADH secretion due to posterior pituitary pathology.
Can be a tumor, head trauma, granulomatous disease involving the hypothalamic pituitary area, CNS infection, cerebral vascular disorder

Question 3

The clinical features of central diabete insipidus are

Answer 3

• Polyuria (pee too much) and polydypsia (excessive thirst)
• Hypernatremia
• Low urine osmolality and specific gravity
• Nocturia is usually present and can lead to chronic tiredness and poor performance at work or school.

Question 4

Water deprivation will do what to urine osmolality with central diabetes insipidus

Answer 4

NOTHING> urine osmolality will still be low

Question 5

Treatment of Central Diabetes insipidus

Answer 5

Desmopressin

Question 6

Nephrogenic Diabetes Insipidus is what

Answer 6

Impaired renal response to ADH

Question 7

No response to Desmopressin in

Answer 7

Nephrogenic DI

Question 8

SIAD

Answer 8

Excessive ADH secretion

Question 9

ADH and Oxytocin have what structure

Answer 9

nonapeptide

Question 10

Stimuli that influence AVP Release?

Answer 10

1) Osmoregulation: primary regulator, Increases in osmolarity cause osmoreceptors in the hypothalamus to shrink. This alters the electric activity of the neurons and increases AVP release. Osmolarity maintained within a very narrow range, 280-296
2) Volume regulation: decreases in plasma volume sensed by stretched receptors in the left atrium lead to increased vasopressin release due to decreased inhibitor pulses from the left atrium to the hypothalamus
3) Baroreceptor Activation in response to hypotension: increased AVP
4) Neural regulation
5) Aging
6) Pharmacologic influences
7) Water Deprivation

Question 11

ADH and Cortisol have opposite effects. Explain

Answer 11

Cortisol raises the osmotic threshold for AVP secretion

Question 12

Which aquaporin is the major mediator of vasopressin action in the kidney and where is it located?

Answer 12

AQP2…collecting duct

Question 13

Conditions associated with water retention: CHF, Pregnancy, SIADH are often associated with what>

Answer 13

increased AQP2 expression

Question 14

polyuria=

Answer 14

urine volume greater than 2.5 liters in 24 hours

Question 15

Central DI

Answer 15

Plasma ADH is low and doesn’t increase with addition of hypertonic saline

Question 16

Central DI pts respond to AVP administration

Answer 16

Nephrogenic DI pts do not

Question 17

What would plasma osmolality and urine osmolality be like in pts who have a habitual habit of drinking too much water

Answer 17

Both would be low

Question 18

Water deprivation test would do what to the urine osmolality of someone with polydipsia

Answer 18

Cause it to increase. There is nothing wrong with their ADH secretion or sensitivity to ADH.

Question 19

Causes of SIADH

Answer 19

Malignant tumors with autonomous AVP release (lung cancer- small cell)
Non-malignant pulmonary disease
CNS disorders like meningitis
Drugs

Question 20

What happens to sodium levels in SIADH

Answer 20

They decrease, sodium secretion enhanced. Most likely because of suppression of Aldosterone release due to high plasma volume.

Question 21

Suspect SIADH when a pt has

Answer 21

hyponatremia with a urinary osmolality that is hypertonic relative to the plasma

Question 22

What are the primary stimuli for oxytocin release

Answer 22

mechanical distension of the reprod tract and suckling at the nipples

Question 23

Oxytocin has some ADH action due to its biochemical similarity. Pharmacological doses of oxytocin used for induction of labor can throw off water balance in women because of this.

Answer 23

truth