35. SIADH Flashcards Preview

Endocrine > 35. SIADH > Flashcards

Flashcards in 35. SIADH Deck (27):
1

causes of SIADH

1. ectopic ADH ( eg. small cell lung cancer(
2. CNS disorfer / heat trauma
3. Pulmonary disease
4. Drugs ( eg cyclophosphamide)

2

drug that causes SIADH

cyclophosphamide

3

SIADH characteristics

1. excessive free water retention
2. Euvolemic hyponatremia with continued urinary Na+ excretion
3. urine osm > serum osm

4

SIADH treatment

1. fluid restriction
2. IV hypertonic salin
3. ASH antagonists
4. salt tablets

5

ASH antagonists - drugs

1. demeclocycline
2. conivaptan
3. tolvaptran

6

SIADH - body respond to water retention with

decreases aldosterone , increases ANP + BNP ---> increased Na+ secretion --> normalization of extracellular fluid volume ---> euvolemic hyponatremia

7

SIADH - body decreases aldosterone to

maintain nerar - normal volume status

8

SIADH - NA+ ? ( why?)

hyponatremia
decreased aldosterone to maintain near normal volume status

9

severe hyponatremia can lead to

1. cerebral edema
2. seizures

10

severe hyponatremia - correct .... ( and why)

slowly
to prevent osmotic demyelination syndrome

11

osmotic demyelination syndrome - also known as

central pontine myelinolysis

12

pegvisomant mechanism of action

GH recptor antagonist

13

octreotide mechanism of action

somatostatin analog

14

Laron syndrome - mechanism

Dwarfism : defective growth hormone receptor --> decreased linear growth

15

Laron syndrome - lab

increased GH
decreased IGF-1

16

Laron syndrome - clinical feature

1.short height,
2.small head circumference,
3.characteristic facies with saddle nose and prominent
forehead,
4.delayed skeletal maturation,
5.small genitalia.

17

Nelson syndrome - mechanism

Enlargement of existing ACTH-secreting pituitary adenoma after bilateral adrenalectomy for
refractory Cushing disease (due to removal of cortisol feedback mechanism).

18

Nelson syndrome - presents with

1. headaches
3. hyperpigmentation
2.bitemporal hemianopia

19

Nelson syndrome - treatment

pituitary irradiation or surgical resection

20

secondary causes of neprhogenic Diabetes insipidus

1. hypercalcemia
b. lithium
c. demeclocycline

21

• A patient with COPD is found to be hyponatremic, with high urine osmolarity and low serum osmolarity. What is the likely diagnosis?

SIADH, or syndrome of inappropriate antidiuretic hormone secretion, which can be caused by lung cancer

22

• A patient with recently diagnosed small cell lung cancer retains fluid. How do his serum and urine osmolarities compare? Pathophysiology?

Urine > serum osmolarity; SIADH (ectopic ADH from small cell lung cancer) causes low aldosterone to maintain near-normal volume status

23

• A patient with hyponatremia and fluid retention has SIADH (syndrome of inappropriate antidiuretic hormone secretion). Possible causes?

Ectopic ADH production (e.g., small cell lung cancer), certain drugs (e.g., cyclophosphamide), CNS disease or head trauma, pulmonary disease

24

• A patient with SIADH has seizures. How could this have been prevented?

Fluid restriction, hypertonic saline, conivaptan, tolvaptan, or demeclocycline, slow hyponatremia correction to avoid osmotic demyelination

25

• An 80-year-old smoker with COPD gains 10 pounds in 2 days; his urine specific gravity is 1.040. What is the likely ectopic source of ADH?

Small cell lung cancer (paraneoplastic syndrome)—the patient is predisposed to this cancer because he smokes

26

• A patient is diagnosed with SIADH. Physical exam is negative for peripheral edema, JVD, or pulmonary edema. Why is this?

In SIADH, the body responds to water retention by decreasing aldosterone (causing hyponatremia) to maintain near-normal volume status

27

• A patient with head trauma has SIADH. What are three features of his condition?


Free water retention, urinary sodium excretion with euvolemic hyponatremia, urine osmolality > serum osmolality