Electrolyte Disorders

Question 1

What is the normal range for sodium

Answer 1

136-145

Question 2

What is the principle solute involved in determining ECF osmolarity and fluid volume balance

Answer 2

Sodium

Question 3

What happens if there is a increase/decrease in Extracellular Na+

Answer 3

Increases
*osmotic gradient
*water leaving the cell
Decrease
*osmotic gradient
*Water enters the cell

Question 4

What happens when sodium balance changes

Answer 4

It is associated with fluid balance disorders

Question 5

What does water follow

Answer 5

Salt

Question 6

What is hyponatremia

Answer 6

Serum sodium <136

Question 7

What is the etiology behind hyponatremia

Answer 7

Common in post-op patients
*ADH is secreted due to pain, n/v, opiates and ventilation

Question 8

What is hyponatremia exacerbated by?

Answer 8

Rapid parenteral adminsitration of hypotonic fluids
*may results from hyperglycemia (pseudo hyponatremia)
*fix glucose if pseudo hyponatremia happens

Question 9

What is the euvolemic etiology of hyponatremia

Answer 9

Volume is okay, sodium is low
1. With Urine osmolarity >100
*SIADH, hypothyroid, thiazides
3. With urine osmolarity <100
*psychogenic polydipsia (drinking gallons of water)

Question 10

What is hypovolemic cause of hyponatremia / hyper

Answer 10

Hypo
*GI loses
*burns
*3rd spacing
*diuretics
*decreased aldosterone
Hyper
*CHF
*nephrotic syndrome
*cirrhosis

Question 11

How will a patient present with acute / chronic hyponatremia

Answer 11

Acute
*CNS dysfunction (Monro-Kellile Hypothesis)
*MS change- obtunded, coma, seizure
Chronic
*asymptomatic

Question 12

What is monro-kellie hypothesis

Answer 12

1. Brain cells swell in a fixed volume space

Question 13

What is the treatment for hyponatremia

Answer 13

Dependent on cause and severity
1. Fluid restriction
*add salt tabs
2. D/c diuretic is cause (thiazide)
3. Isotonic fluid replacement with IV NS or LR (slowly)
*no more than 4-6 mEq/L/D

Question 14

What happens if the isotonic fluid replacement is not done slowly

Answer 14

Osmotic central pointe demyelination

Question 15

What is the treatment of severe hyponatremia

Answer 15

1. 3% hypertonic saline (Na Cl-)
2. When sodium <120 and neurologic symptoms present
   *no more than 8 mmolL/d with correction of 1-2 mmol/L/h

Question 16

Does correcting the sodium replace the pharmacologic intervention in a seizing patient

Answer 16

No
*give benzos

Question 17

What is the goal of treating hyponatremia

Answer 17

Increase NA+enough to eliminate CNS disturbance

Question 18

What is hypernatremia

Answer 18

Serum sodium >144

Question 19

What is the etiology of hypernatremia

Answer 19

Loss of free water when patients do not have access
1. Bedbound, incapacitated
2. Diabetes insipidus
3. Extra renal losses fever burns, GI losses

Question 20

What can induced hypernatremia e useful for?

Answer 20

In patients with TVI to reduce cerebral edema and decreases intracranial pressure

Question 21

What are the signs and symptoms of hypernatremai

Answer 21

1. Restlessness, weakness, dry
2. Febrile
3. Tachycardia
4. Muscle tremors
5. Pulmonary and peripheral edema

Question 22

What is the treatment of hypernatremia

Answer 22

1. Replace water
2. Calculate the free water deficit
3. Give maintenance fluids and electrolytes at the same time
4. Replace 1/2 of the free water deficit in the first 12 ours
5. Monitor serum sodium

Question 23

How to calculate the free water deficit

Answer 23

1. For every liter of deficit, serum sodium rises by 3mEq/L
2. Subtract a normal mid-range value of 140 from current serum sodium value
3. Divide the result by 3

EX: patient with serum sodium of 161
161-140=21
21/3= 7L (fluid deficit to be replaced)