Exam #2: Sodium Disorders

Question 1

What does “TIE 60, 40, 20” refer to?

Answer 1

• TBW = 60% of total body weight
• ICF = 40% of total body weight
• ECF = 20% of total body weight

Question 2

What is the primary ECF ion, and is it a cation or anion?

Answer 2

Na+ (cation)

Question 3

If fluid is moved from ECF → ICF, what happens to cells?

Answer 3

Cells SWELL

Question 4

If fluid is moved from ICF → ECF, what happens to cells?

Answer 4

Cells SHRINK

Question 5

If there is an abnormal serum [Na+], what does this indicate?

Answer 5

Water regulation disorder

- Serum [Na+] refers to amount of water relative to Na+ in ECF

Question 6

What is the major determinant of ECF volume?

Answer 6

Total amount of Na+ in ECF

Question 7

If Na+ is LOW, what does this mean for ECF volume, and what is another name for this?

How does this present clinically?

Answer 7

Low Na+ → low ECFV = hypovolemia

- Presents as poor skin turgor, dry mucous membranes (dehydration)

Question 8

If Na+ is HIGH, what does this mean for ECF volume, and what is another name for this?

How does this present clinically?

Answer 8

High Na+ → high ECFV = hypervolemia

- Presents as edema/fluid retention

Question 9

What general condition is associated with etiologies of GI loss, renal loss, skin loss, sequestration without loss?

Answer 9

Hypovolemia

Question 10

What general condition is associated with etiologies of liver disease, HF, acute/chronic renal failure, nephrotic syndrome, primary hyperaldosteronism, Cushing’s, pregnancy?

Answer 10

Hypervolemia

Question 11

What are the three major causes of Hypervolemia?

Answer 11

• Liver disease
• HF
• Renal failure (acute/chronic)

Question 12

What general condition is associated with increased thirst, decreased sweating; poor skin turgor, dry mucous membranes; oliguria, CNS depression; weakness and muscle cramps; low BP with postural dizziness; high pulse?

Answer 12

Hypovolemia

Question 13

What general condition is associated with edema, SOB, orthopnea, PND, JVD, hepatojugular reflux, crackles?

Answer 13

Hypervolemia

Question 14

What two factors influence water retention?

Answer 14

• Thirst

- ADH

Question 15

What is the primary factor that influences salt retention, and what are the two main results?

Answer 15

RAAS

• Na+ retention
• K+ excretion
• Also ANP and general renal function (GFR, RBF)

Question 16

What is the most common electrolyte abnormality in hospitalized patients?

Answer 16

Hyponatremia

Question 17

What constitutes Hyponatremia? With what two populations is it more common in?

Answer 17

Serum [Na+] below 125 (or symptomatic)

- More common in very young or very old

Question 18

What condition involves falsely low serum [Na+] BUT normal osmolality (isoosmolar)?

Answer 18

Pseudohyponatremia

Question 19

What two causes are often associated with Pseudohyponatremia?

Answer 19

• Hyperlipidemia

- Hyperproteinemia

Question 20

What condition involves hyperosmolar state due to increased solute in ECF causing shift of water from ICF to ECF → lower serum [Na+]?

Answer 20

Redistributive/Hyperosmolar hyponatremia

Question 21

What is often the cause of Redistributive/Hyperosmolar hyponatremia, and why?

Answer 21

Hyperglycemia

- High glucose in ECF causes shift of water from ICF → ECF = lowers serum Na

Question 22

What are the three primary causes of Hypervolemic Hyponatremia?

How do you treat it?

Answer 22

• Liver failure
• HF
• Renal failure

Treat underlying cause (diuretics, dialysis, fluid restrictions)

Question 23

What are the five possible causes of Hyponatremia?

Answer 23

• Pseudohyponatremia
• Redistributive/Hyperosmolar hyponatremia
• Hypovolemic Hyponatremia
• Euvolemic Hyponatremia
• Hypervolemic Hyponatremia

Question 24

What condition is considered a laboratory artifact?

Answer 24

Pseudohyponatremia

Question 25

With Hypovolemic Hyponatremia, if urine Na+ >20, what is the primary cause?

Answer 25

Diuretics (Thiazides) | - Also cerebral salt wasting or RTA

Question 26

With Hypovolemic Hyponatremia, if urine Na+ <20, what is the primary cause?

Answer 26

Gastroenteritis (V/D) | - Also, third space losses (burns, pancreatitis)

Question 27

What is the primary treatment for Hypovolemic Hyponatremia?

Answer 27

Replace fluids lost

Question 28

What are the four primary causes of Euvolemic Hyponatremia?

Answer 28

- SIADH - Hypothyroidism - Adrenal insufficiency - Psychogenic polydipsia

Question 29

What is the primary treatment for Euvolemic Hyponatremia?

Answer 29

Fluid restriction

Question 30

What general condition involves HA, dizziness, N/V, lethargy, weakness, confusion, hypoventilation, seizures, coma, death?

Answer 30

HYPOnatremia

Question 31

Severity of symptoms of Hyponatremia depends on level of...

Answer 31

Cerebral edema | - If ECF → ICF = brain cells swell

Question 32

What should always be considered in the diagnosis of Hyponatremia?

Answer 32

FLUID STATUS (hyper vs. eu vs. hypo)

Question 33

What condition involves concentrated urine with low serum osmolality and euvolemia?

Answer 33

SIADH | - Possible cause of Euvolemic Hyponatremia

Question 34

What condition is diagnosed as high urine osmolality and low serum osmolality?

Answer 34

SIADH | - Possible cause of Euvolemic Hyponatremia

Question 35

What condition involves too much ADH but has normal cortisol and thyroid levels?

Answer 35

SIADH | - Possible cause of Euvolemic Hyponatremia

Question 36

What is a possible cause of SIADH?

Answer 36

Pulmonary disease (SCLC)

Question 37

What is the recommended treatment for Hyponatremia (if serum [Na+] <125 OR symptomatic)?

Answer 37

Hospitalize

Question 38

What is a possible complication of Hyponatremia if Na+ is not corrected slowly (especially chronic)?

Answer 38

Cerebral Pontine Myelinolysis (CPM) | - Focal demyelination in pons and extra-pontine areas that is NOT reversible

Question 39

What is the recommended rate of correction for Hyponatremia?

Answer 39

Less than 8 mEq/L in first 24 hours | - Should be about 4-6 mEq/L in first 24 hours

Question 40

What constitutes Hypernatremia?

Answer 40

Serum [Na+] above 145

Question 41

What is the general etiology of Hypernatremia? What are two other possible causes?

Answer 41

Excessive water loss from body | - Also too little dietary water or too much dietary salt

Question 42

Is Cerebral Pontine Myelinolysis (CPM) reversible? How and when would this present?

Answer 42

NOT reversible - Dysarthria, dysphagia, seizures, AMS - Begins 1-3 DAYS after over-correction

Question 43

What general condition is often asymptomatic… Thirst/signs of volume depletion; AMS, weakness; NM irritability; focal neuro deficits; seizures, coma?

Answer 43

HYPERnatremia

Question 44

What are three possible causes of Hypernatremia?

Answer 44

- Osmotic diuresis = hyperglycemia, Mannitol | - Diuretics (Loops)

Question 45

What is the body's normal response to Hypernatremia (2 steps)?

Answer 45

1. Create thirst to increase fluid intake | 2. Concentrate urine to prevent further water loss

Question 46

What condition involves urinary water loss but high serum [Na+] = urine dilute but should be concentrated, and what type of natremia is it associated with?

Answer 46

``` Diabetes Insipidus (DI) - Associated with HYPERnatremia ```

Question 47

What are the two types of Diabetes Insipidus (DI), and what is the cause of each?

Answer 47

- Neurogenic/Central DI: due to impaired ADH secretion | - Nephrogenic DI: lack of kidney response to ADH (sufficient ADH present though)

Question 48

How do you treat Neurogenic/Central DI?

Answer 48

Desmopressin

Question 49

How do you treat Nephrogenic DI (2)?

Answer 49

Thiazides, Amiloride | - CANNOT be treated with Desmopressin

Question 50

What is the general treatment of Hypernatremia (2)?

Answer 50

- STOP water loss | - REPLACE water loss (but not too rapidly - should take days)