Disorders of Na and K Regulation

Question 1

Solute per 1 L of solvent

Answer 1

Osmolarity

Question 2

Solute per 1 Kg of solvent

Answer 2

Osmolality

Question 3

What is the normal serum osmolarity?

Answer 3

280-290

Question 4

If the serum osmolarity is increased, what 2 systems will regulate it?

Answer 4

ADH

Thirst

Question 5

What 2 receptor types can sense increased serum osmolarity and can activate ADH release?

Answer 5

1. Hypothalamus osmoreceptors

2. Arterial baroreceptors

Question 6

What is the normal serum value for sodium?

Answer 6

140

Question 7

What is the normal serum range for potassium?

Answer 7

3.5 - 4.5

Question 8

What is the normal serum range for chloride?

Answer 8

98 - 112

Question 9

Hyponatremia

Answer 9

Na < 135

Question 10

In what patients is Hyponatremia common and what does it result from?

Answer 10

Common in hospitalized patients

= Results from an INCREASE in total body water

Question 11

Usually Hyponatremia is _____

Answer 11

Asymptomatic

Question 12

If sodium levels drop below 125, what are some possible symptoms?

Answer 12

CNS - headache, dizzy, confusion, seizure, coma

Question 13

When drawing labs, they should be drawn ______

Answer 13

Simultaneously

Question 14

What are 2 steps to assessing Hyponatremia?

Answer 14

1. Measure serum osmolarity

2. Measure urine Na+ and urine osmolarity

Question 15

If the serum osmolarity is hypotonic hyponatremia, what should then be assessed?

Answer 15

Volume status

Question 16

What is an example of a disease that can cause Hyponatremia and a malignancy associated?

Answer 16

SIADH

– Small Cell Lung Cancer can cause ectopic ADH release

Question 17

What is the treatment for Hyponatremia?

Answer 17

Hypertonic Saline (3%)

Question 18

What is a potential side effect if Hyponatremia is corrected TOO FAST?

Answer 18

Osmotic Demyelination Syndrome

– locked in syndrome and other CNS issues

Question 19

Hypernatremia

Answer 19

Na+ > 145

Question 20

Hypernatremia commonly occurs in what patients and is associated with what risk factors?

Answer 20

Infants and elderly

– Trauma, burns, dementia and uncontrolled diabetes

Question 21

What 2 things can cause Hypernatremia and which is the most common?

Answer 21

1. Dehydration – most common

2. Sodium overload

Question 22

What are the main symptoms with Hypernatremia?

Answer 22

Neurologic

– Intracranial hemorrhage

Question 23

What is the treatment for Hypernatremia?

Answer 23

Correct sodium and replace water loss

Question 24

If Sodium levels are corrected too fast with Hypernatremia, what is there a risk for?

Answer 24

Cerebral edema

Question 25

What organ primarily controls serum potassium?

Answer 25

Kidney

Question 26

The immediate response to changes in K+ levels are controlled by?

Answer 26

Transcellular shift -- Na/K ATPase

Question 27

The long term control to changes in K+ is controlled by?

Answer 27

Renal K+ excretion in distal nephron

Question 28

Hyperkalemia

Answer 28

K+ > 5

Question 29

What are the main symptoms with Hyperkalemia?

Answer 29

Cardiac arrhythmias Muscle weakness Metabolic ACIDOSIS

Question 30

What changes will be seen on ECG with Hyperkalemia?

Answer 30

Widened QRS Peaked T wave -- membrane potential less negative

Question 31

What 2 mechanisms usually cause Hyperkalemia?

Answer 31

1. Transcellular shift | 2. Decreased renal K+ excretion

Question 32

What are some transcellular shift causes of Hyperkalemia?

Answer 32

Pseudohyperkalemia (RBC hemolysis) Decreased insulin Metabolic acidosis

Question 33

What are some decreased renal K+ excretion causes of Hyperkalemia?

Answer 33

Decreased Aldosterone | Kidney injury

Question 34

Hypokalemia

Answer 34

K+ < 3.5

Question 35

What are the symptoms with Hypokalemia?

Answer 35

Cardiac arrhythmias Muscle weakness Metabolic ALKALOSIS Rhabdomyolysis

Question 36

What ECG change is seen with Hypokalemia?

Answer 36

U wave | -- membrane potential is more negative

Question 37

What are the general causes of Hypokalemia?

Answer 37

Transcellular shift Extrarenal loss Renal loss

Question 38

What are some causes of a transcellular shift that causes Hypokalemia?

Answer 38

Insulin Beta2 Agonist Metabolic Alkalosis

Question 39

What are some extrarenal causes of Hypokalemia?

Answer 39

GI loss - N/V, diarrhea and sweat