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Flashcards in Dysnatremias Deck (106)
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1

What is hypernatremia?

Sodium over 145

2

What are the 2 main phases of hypernatremia?

Generation and maintenance

3

What are 2 forms of generation phase of hypernatremia?

1. Loss of later
2. Gain of salt (sodium ingestion via salt tabls and infant formula, mineralocorticoid excess, and iatrogenic via IV fluids, dialysis, tube feeds, and TPN)

4

What are 2 forms of the maintenance phase of hypernatremia?

1. Failure to drink water
2. Inability to sense thirst

5

Are hyper and hypo natremia issues with salt?

NO they are issues with water

6

General view of hypernatremia?

Loss of water leading to dehydration
-If patient can take in H20 normally, it shoudl correct itself

7

What is hypernatremia most often caused by?

A loss of water either renal or extra renal

8

What are 2 renal causes for loss of water leading to hypernatremia?

1. Diabetes insipidus
2. Osmotic diuresis

9

What are the 2 types of diabetes insipidus?

1. Central
2. Nephrogenic

10

Describe central DI?

Inability of brain to release ADH
-Caused by brain injury (iatrogenic (surgery), trauma, tumors, ischemic insults, infections)
-Kidneys are normal

11

Does central DI respond to ADH when supplied?

YES

12

Describe nephrogenic DI?

Inability of kidney to respond to ADH
-The collecting tubules are impermeable to water (can be caused by chronic lithium use, congenital, or demeclocycline)
-Other causes of poor response to ADH include hypercalcemia, loop diuretics, hypokalemia, sickle cell

13

What is the 1st step to diagnosing DI?

Water restriction test...this differentiates psychogenic polydipsia, CDI, and NDA

14

In the water restriction test, what is seen if the patient has hyponatremia due to psychogenic polydipsia?

There is a progressive increase in the urine osmolarity

15

What is seen in the water restriction test if the patient has NDI or CDI?

NOTHING...no change in urine osmolarity

16

What will happen if you give ADH to someone with CDI?

THe urine osmolarity will increase

17

What will happen if you give ADH to someone with NDI?

No change in urine osmolarity

18

What will happen if you give ADH to someone with psychogenic polydipsia?

No change in urine osmolarity

19

What is the treatment for psychogenic polydipsia?

STOP DRINKING

20

What is the treatment for CDI?

DDAVP (desmopressin)

21

What is the treatment for NDI?

Diuretics...thiazide with K-sparing will increase water resorption in ADH independent regions of the kidney

22

What are 3 causes of osmotic diuresis?

1. Hyperglycemia
2. Post-obstructive (can't void... like in BPH)
3. Mannitol: Diuretic that makes you pee a lot... have to keep up with fluid intake

23

Generally, what is happening in osmotic diuresis?

You are peeing out lots of water and become hypernatremia (you need to drink H20)...

24

What are 3 sources of extra renal loss of water?

1. Skin losses: Burns
2. Pulmonary Losses: Advanced COPD, breating too fast/too often
3. GI losses: Acute diarrhea, IBD

25

What are signs and symptoms of hypernatremia?

Confusion, lethargy, weakness, seizure, coma

26

What is the risk in treating hypernatremia?

The speed of correction

27

What is the speed of correction in chronic (over 48 hours) asymptomatic hypernatrmia?

Don't excees 0.5mEq/L/hr

28

What is the speed of correction in acute (less than 48 hours) symptomatic hypernatremia?

1-1.15 mEq/L/hr until symptoms improve, then slow the rate to 0.5mEw/L/hr

29

Why do we recheck Na levels frequently when correcting them?

Want to avoid an undesirable rate

30

What is the rate at which we should give fluids?

Deficit/time