Na Basics

Question 1

Problem with significant increases or decreases in Na?

Answer 1

Changes in cell volume that can be life threatening

Question 2

Normal plasma osmolality

Answer 2

275-290 mosm/L

Question 3

Risk of not treating acute, severe hyponatremia

Answer 3

Coma, Seizure, Brain herniation

Question 4

Overly rapid correction of chronic mild hyponatremia can lead to…

Answer 4

Osmotic demyelinization

Question 5

What is pseudohyponatremia?

Answer 5

Elevation in serum proteins/Lipids

Causes an osmotic translocation of water from cells to serum

Question 6

Hyponatremia with an increased plasma osmolarity – what do you suspect?

Answer 6

Heightened levels of glucose and mannitol

Question 7

Common causes of pseudohyponatremia

Answer 7

Retained solutes – sucrose/maltose

Glucose, Mannitol, Glycine

Question 8

Calculated plasma osmolality?

Answer 8

2 (Na+K) + (BUN/2.8) + (Glucose/18)

Question 9

What is osmolal gap?

Answer 9

Measured plasma osmolality minus the calculated value

Question 10

How much shoudl you add to the Na concentration for every 100 mg/dL the glucose is over 100

Answer 10

1.6

“Sweet 16”

Question 11

If you have a low serum osmolarity hyponatremic patient, what next piece of information will have you narrow down thte potential causes

Answer 11

ECFv

Question 12

low serum osmolarity hyponatremic patient with high ECFv, what do you suspect?>

Answer 12

CHF, Cirrhosis, Nephrosis

Question 13

low serum osmolarity hyponatremic patient with normal ECFv. What do you suspect?

Answer 13

Diminished thyroid/adrenal
SIADH
Water Intoxication

Question 14

low serum osmolarity hyponatremic patient with low ECFv. What do you suspect?

Answer 14

Renal - Diuretics, ACE-I, ARB

Extra-renal - Bleeding/Burns, GI Loss, Pancreatitis

Question 15

Difference between SIADH and NSIAD

Answer 15

SIADH – Inappropriate secretion of ADH

NSIAD - Nephrogenic Syndrome of inappropriate diuresis (an activating mutation in ADH receptor)

Question 16

What happens when a person has a low osmotic load and a high fluid intake

Answer 16

Beer Drinkers potomania

Tea and Toast Diet

Question 17

Mechanism of cerebral salt wasting

Answer 17

Urinary Na loss causes volume depletion, stimulating ADH secretion –> both loss + H2O retention

Question 18

The “dreaded complication of raising Na too fast

Answer 18

Central Pontine Myelinolysis

Disarthria/phagia, pareisis, coma, seizures

Question 19

When would you need to do a desmopressin rescue?

Answer 19

Exceeding target Na in treating hyponatremia

Question 20

Increased risk for myelinosis if…

Answer 20

chornic EtOH
hypokalemia
malnourished
Burns
Liver Disease

Question 21

Important treatments for acute phase of chronic hyponatremia

Answer 21

Fluid Restriction
Isotonic or Hypertonic Solution
Salt Pills
Desmopressin+ 3% Normal Saline

Question 22

Causes of acute hyponatremia?

Answer 22

Water intox
Ecstasy
Marathon Runners
Postoperative

Question 23

Effects of acute water intoxication

Answer 23

Seizure, Coma, Resp Arrest
Neurogenic Pulmonary Edema
Cerebral Edema w/ herniation

Question 24

How fast should chronic hyponatremia be treated?

Answer 24

raise of 6-8 mm/L per day

Question 25

Polyuria is defines as urinating….

Answer 25

more than 3L per day

Question 26

Almost all hypernatremia is caused by…

Answer 26

Unreplaced water loss

water loss into cells (severe exercise, seizures)

Question 27

When might you be able to diagnose hypernatremia within a few hours

Answer 27

Salt water drowning

In this case, treat aggressively with hypotonic fluids

Question 28

Tx for chronic hypernatremia

Answer 28

Slow correction because brain is adapted. Treat too fast – Cerebral edema

Question 29

Tx for acute hypernatremia

Answer 29

Rapid correction – get to norml level in less than 24 hours