Hyponatremia

Question 1

What % of body weight is salt water?

Answer 1

60%

Question 2

What is the equation for blood [Na+]?

Answer 2

Blood [Na+] = total body sodium/total body water

Question 3

Describe the physiological regulations of Na+ conc after a large intake of water

Answer 3

Large water intake
Lower [Na+]
Less ADH release from post pituitary
Less thirst
Less H2O reabsorption in renal collecting ducts
Normalization of [Na+]

Question 4

Where is ADH synthesized?

Answer 4

Hypothalamus

Question 5

Where is ADH stored?

Answer 5

Posterior pituitary

Question 6

What physiological value tends to most sensitively regulate ADH levels?

Answer 6

Serum osmolality

Small changes in osmolality will lead to ADH release/inhibition

Question 7

Define hyponatremia

Answer 7

Excess of total body water relative to total body sodium

Almost always indicates impaired renal water excretion

Question 8

Intrarenal factors that cause Hyponatremia

Answer 8

1. Filtration at glomeruli
2. Delivery of solute to distal nephron sites
3. Reabsorption of solute at distal nephron sites

Question 9

List some causes of hypovolemic hyponatremia

Answer 9

Renal Na+ losses
Diuretics
Primary adrenal insufficiency (Addison’s Disease)
Salt wasting nephropathies

Extrarenal Na+ losses
Diarrhea
Vomiting
Excess sweating

Question 10

List some symptoms of hypovolemic hyponatremia

Answer 10

Flat neck veins
Decreased skin turgor
Orthostatic hypotension

Question 11

List some causes of euvolemic hyponatremia

Answer 11

SIADH
Hypothyroidism
Psychogenic polydipsia

Question 12

List some causes of hypervolemic hyponatremia

Answer 12

CHF
Liver cirrhosis
Renal failure

Question 13

List some symptoms of hypervolemic hyponatremia

Answer 13

Edema

Question 14

What does a normal Urine conc of Na+ indicate? (>20 mEq/L)

Answer 14

Renal loss of Na+ or excess ADH

Question 15

What does a low Urine conc of Na+ indicate? (

Answer 15

Extrarenal loss of Na+ or an edematous disorder

Question 16

Treatment for Hypervolemic hyponatremia

Answer 16

Fluid restriction and diuretics

Question 17

Treatment for Hypovolemic hyponatremia

Answer 17

Physiologic saline

Question 18

Treatment for Euvolemic hyponatremia

Answer 18

Asymptomatic -> water restriction

Symptomatic -> medical emergency; use hypertonic saline with or without diuretics

Question 19

Define Hypernatremia

Answer 19

Increased [Na+] relative to total body water

Question 20

List some symptoms of hypovolemic hypernatremia

Answer 20

Renal Na+ losses
Duretics with inadequate water intake
Post obstructive diuresis
Tubular injury

Extrarenal Na+ losses
Sweating
Diarrhea
Vomiting with inadequate water intake

Question 21

List some symptoms of euvolemic hypernatremia

Answer 21

Central diabetes insipidus
Nephrogenic diabetes insipidus
Decreased thirst and water intake

Question 22

List some symptoms of hypervolemic hypernatremia

Answer 22

Hypertonic fluid administration
Mineralocorticoid excess states
Salt poisoning (sea water ingestion)

Question 23

Treatment for Euvolemic hypernatremia

Answer 23

Water administration

May also give ADH in central diabetes insipidus

Question 24

Treatment for Hypovolemic hypernatremia

Answer 24

Hypotonic fluids

Question 25

Treatment for Hypervolemic hypernatremia

Answer 25

May require both water administration plus diuretics or dialysis to remove excess Na+