Sodium and Water Disorders

Question 1

Intracellular fluid

Answer 1

75%; potassium, magnesium, phosphate

Question 2

Extracellular fluid

Answer 2

25%; sodium, chloride, bicarbonate

Question 3

homeostasis of ICF and ECF maintained by

Answer 3

Na+/K+/ATPase pumps

Question 4

what establishes the tonicity or osmolality of ECF?

Answer 4

Sodium

Question 5

isotonic HYPOnatremia

Answer 5

normal serum osmololity (280); pseudohyponatremia and prostate surgery; increased large molecules (protein fats) compared to sodium; usually due to lab error

Question 6

HYPERtonic HYPOnatremia

Answer 6

elevated serum osmolality (>280); increase in solutes in ECF (hyperglycemia, osmotic diuretics, irrigation fluids, propylene glycol, ehtylene glycol); water moves from ICF to ECF causing excess fluid; must calculate osmolality and osmolar gap

Question 7

osmolar gap

Answer 7

calculated osmolality – serum osmolality

Question 8

HYPOtonic HYPOnatremia

Answer 8

serum sodium

Question 9

symptoms of HYPOnatremia

Answer 9

CNS dysfunction; cerebral edema

Question 10

HYPOnatremia sodium

Answer 10

start symptoms; sodium

Question 11

chronic HYPOnatremia

Answer 11

brain adapts to the low sodium; rapid correction could lead to central pontine myelinolysis (water from ICF to ECF)

Question 12

central pontine myelinolysis

Answer 12

greatest risk is elderly, alcoholics, primary polydipsia

Question 13

need to categorize HYPOtonic HYPOnatremia to three groups

Answer 13

hypervolemic, euvolemic, hypovolemic

Question 14

HYPOvolemic HYPOtonic HYPOnatremia

Answer 14

sodium and water loss; raised hematocrit; BUN to creatinine ratio of >20, urine osmolality >450; treatment is IV fluids, discontinue diuretics, replace mineralocorticoids

Question 15

HYPERvolemic HYPOtonic HYPOnatremia

Answer 15

caused by cirrhosis, renal disease, CHF; increased water and sodium in ECF; edema, decreased renal perfusion pressure; release ADH; treatment is fluid restriction, sodium restriction, loop diuretic

Question 16

euvolemic HYPOtonic HYPOnatremia

Answer 16

syndrome of inappropriate secretion of ADH, hypothyroidism, adrenal insufficiency, renal failure; urine osmolality is >100 then SIADH; urine osmolality is

Question 17

treatment for acute HYPOnatremia

Answer 17

3% saline (hypertonic saline) 1mL/kg/hr; very severe rate is 2-3

Question 18

goal for acute HYPOnatremia tmt

Answer 18

increase sodium by 0.5-1 mEq/hr no >10-12; goal is 125

Question 19

treatment drugs for chroninc HYPOnatremia

Answer 19

demeclocycline and lithium both inhibit ADH

Question 20

HYPERnatremia

Answer 20

serum sodium >145; water deficit relative to sodium

Question 21

high risk for HYPERnatremia

Answer 21

infants, elderly, fever, intubated, D/V, osmotic diuresis, diabetes insipidus

Question 22

central pontine myelinosis

Answer 22

water moves from ICF to ECF and cells shrink; postural hypotension, decreased skin turgor, decrease capillary refill, seizure and coma

Question 23

HYPERnatremia goals

Answer 23

reduce sodium by 10mEq//l/d; target sodium is 145

Question 24

HYPERnatremia treatment

Answer 24

only use hypotonic fluids (pure water, 5% dextrose, 0.45% NaCl, 0.2% NaCl)