Posterior Pituitary- Hypo/hypernatremia Flashcards Preview

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Flashcards in Posterior Pituitary- Hypo/hypernatremia Deck (23):
1

Diabetes means

urinating too much

2

What is Central Diabetes Insipidus

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

3

The clinical features of central diabete insipidus are

- 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.

4

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

NOTHING> urine osmolality will still be low

5

Treatment of Central Diabetes insipidus

Desmopressin

6

Nephrogenic Diabetes Insipidus is what

Impaired renal response to ADH

7

No response to Desmopressin in

Nephrogenic DI

8

SIAD

Excessive ADH secretion

9

ADH and Oxytocin have what structure

nonapeptide

10

Stimuli that influence AVP Release?

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

11

ADH and Cortisol have opposite effects. Explain

Cortisol raises the osmotic threshold for AVP secretion

12

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

AQP2...collecting duct

13

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

increased AQP2 expression

14

polyuria=

urine volume greater than 2.5 liters in 24 hours

15

Central DI

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

16

Central DI pts respond to AVP administration

Nephrogenic DI pts do not

17

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

Both would be low

18

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

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

19

Causes of SIADH

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

20

What happens to sodium levels in SIADH

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

21

Suspect SIADH when a pt has

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

22

What are the primary stimuli for oxytocin release

mechanical distension of the reprod tract and suckling at the nipples

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.

truth