Electrolytes

Question 1

What percentage of our body weight is water?

Answer 1

60%

Question 2

How much of the 60% is intracellular & how much is extracellular?

Answer 2

• Intracellular is about 2/3 (40%)
• Extracellular is about 1/3 (20%)

Question 3

What is osmolality?

Answer 3

of particles in solution

Question 3

Is Na+ intracellular or extracellular?

Answer 3

major extracellular cation

Question 4

What is a normal osmolality?

Answer 4

285-295

Question 5

What is the normal osmolar gap?

Answer 5

10

Question 5

Normal serum Na+

Answer 5

135-145

Question 6

What extracellular anion tends to follow Na+ to maintain electroneutrality?

Answer 6

Cl-

Question 7

What is hyponatremia? And levels mild, mod, severe

Answer 7

Na+ < 135
- Mild 130-134
- Moderate 120-129
- Severe < 120

Question 7

Extra test that could be ran for hyponatremia?

Answer 7

• TSH
• AM cortisol
• BNP

Question 8

What are the 3 types of low osmolality w/ hypoNa+ = “true” hypoNa+?

Answer 8

• Hypervolemic
• Euvolemic
• Hypovolemic

Question 9

Causes of Hypervolemic true hypoNa+

Answer 9

• CHF
• cirrhosis
• renal failure
• hypoalbuminemia

Question 10

Causes of Euvolemic true hypoNa+

Answer 10

• SIADH
• hypothyroidism
• low solute intake, etc.

Question 10

Causes of hypovolemic true hypoNa+

Answer 10

renal & extrarenal losses

Question 10

Causes of normal osmolality w/ hypoNa+ = pseudonatremia

Answer 10

Incr PRO or lipids in blood

Question 10

Causes of high osmolality w/ hyponatremia = pseudohyponatremia

Answer 10

• Hyperglycemia
• Recent mannitol or sorbitol use

Question 10

What do we check when assessing volume status?

Answer 10

-Vital signs
-Orthostatics
-JVP
-Skin turgor
-Mucous membranes
-Peripheral edema

Question 10

Main causes of SIADH

Answer 10

• pulm malignancy
• symptomatic HIV
• Drugs
• Idiopathic

Question 11

Main antidepressant drugs that cause SIADH

Answer 11

• SSRIs

Question 12

RFs of Osmotic Demyelination Syndrome (ODS)
(central pontine myelinosis)

Answer 12

• Serum Na+ < 105 mEq/L
• Chronic hypoNa+ corrected too quickly
• EtOH use
• Malnutrition
• Liver dz

Question 12

Normal serum potassium level

Answer 12

3.5 - 5.2

Question 13

Is K+ intracellular or extracellular?

Answer 13

intracellular

Question 14

Where is most K+ found?

Answer 14

in muscles

Question 15

Normal range for Mg++

Answer 15

1.7 - 2.2

Question 16

Is Mg++ intracellular or extracellular

Answer 16

intracellular

Question 17

What are the levels of hypermagnesemia?

Answer 17

- mild (4-7) - mod (7-12) - severe (>12)

Question 17

Normal Ca++ range

Answer 17

8.5 - 10.5

Question 18

___% of Ca++ in the body is found in the ___

Answer 18

- 99% - bones

Question 18

Describe the remaining 1% of Ca++,

Answer 18

~50% ionized (free) ~40% PRO bound-primarily to albumin

Question 18

Saying for hypercalcemia

Answer 18

“Stones, bones, abdominal groans, & psychiatric overtones”

Question 18

Normal serum phosphorus range

Answer 18

2.5 - 4.5