Hypernatremia and hypo

Question 1

Hypernatremia is defined as levels above? Most often from?

Answer 1

Elevated serum sodium above 145

Most often from water depletion

Question 2

Elderly patients with decreased thirst and acess to fluids are at higher risk of what?

Answer 2

Hypernatremia

Question 3

What is hypernatremia almost always from?

Answer 3

Almost always from inadequate fluid intake or excess water loss. - think about elderly, dementia patients who forget to drink fluids.

Question 4

Water can be lost in the urine in what three ways?

Answer 4

Osmotic diuresis

Diabetes insipidius (central or nephrogenic)

Diuretics can waste water and or sodium - Think thiazide Diuretics.

Question 5

Hypervolemic hypernatremia is most likely caused by?

Answer 5

Iatrogenic from hypertonic saline or dialysis

Hyperaldosteronism.

Question 6

Hypovolemic hypernatremia is most likely caused by?

Answer 6

Renal losses from renal disease or diuretics - thiazide.

Extrarenal losses - vomiting/diarrhea.

Question 7

Euvolemic hypernatremia is most likely caused by?

Answer 7

Hypodipsia - decreased thirst - hypothalamus lesion

diabetes insipidus.

Question 8

What are clinical symptoms of hypernatremia? Early, Next?

Answer 8

Early sx: anorexia - restlessness or n/v

Next: progressive AMS: lethargy or irritability 1st, then stupor or coma.

Question 9

Neurologic signs of hypernatremia?

Answer 9

Twitching, hyperreflexia, ataxia, tremor, seizures.

Question 10

S/S of dehydration?

Answer 10

Dry MM, tenting/poor skin turgor, lack of tears, decreased salivation, tachycardia, hypotension, oliguria/anuria.

Question 11

Acute vs Chronic hypernatremia. How long has chronic been present? What is acute more likely to provoke?

Answer 11

Chronic is hypernatremia lasting longer than 2 days. Less likely to provoke neurologic s/s.

Many patients have underlying neuro disease (impaired thirst). Undergo brain adaptation to hypernatremia.

Acute is more likely to provoke neurologic s/s

Question 12

How do you diagnose hypernatremia?

Answer 12

Cuase is usually obvious from history

BMP - sodium above 145

Question 13

If hypernatremia etiology is unclear what should you order?

Answer 13

Urine and plasma osmolality.

If low sodium in the urine - extrarenal (lower sodium osmolality in urine than blood)

if high sodium in the urine - renal problem.

Question 14

What is the treatment for hypernatremia?

Answer 14

Give dilute fluids to correct the deficit and replace ongoing losses.

Question 15

Treatment of chronic hypernatremia?

Answer 15

Slow correction to avoid rapid fluid movement into the brain –> cerebral edema

Can lead to seizures and coma if done too fast.

D5W IV at a rate of 1.35mL/hr x weight in kg.

a MAX of 10 mEq/L over a 24 hour period.

Question 16

In chronic hypernatremia you don’t want to lower sodium by more than what in a 24 hour period?

Answer 16

Lower serum sodium by max of 10 over a 24 hour period.

Question 17

How do you treat acute hypernatremia?

Answer 17

Happened quickly so reverse quickly.

D5W at a rate of 3-6 mL/kg per hour. After <140 1mL/kg per hour.

Monitor soidum and glucose a 1-2h until na less than 145 - want to go to 140.

Reduce sodium by 1-2 mEq/L each hour.

Question 18

Mortality rate of hypernatremia?

Answer 18

40-60% - many with underlying severe diseases

Question 19

What is the most common electrolyte disorder seen in hospitalized patients?

Answer 19

Hyponatremia

Question 20

Hypervolemic hyponatremia is caused by?

Answer 20

Fluid overload - water is either added or retained –> the amount of sodium in the serum is diluted.

CHF, cirrhosis, IVF, nephrotic syndrome.

Question 21

Hypovolemic hyponatremia is caused by?

Answer 21

Water and sodium is lost (but more sodium than water)

Renal losses - diuretics, especially thiazides.

Extrarenal losses - diarrhea, sweating, blood loss, fluid shifts.

Question 22

Euvolemic hyponatremia is caused by (5)

Answer 22

Adrenal insufficiency

Polydipsia - primary or psychogenic (hypothalamus lesions)

Hypothyroidism

Syndrome of inappropriate antidiuretic hormone (SIADH) - brain or lung issue

Reset osmostat.

Question 23

How do you classify by tonicity?

Answer 23

Hypotonic, isotonic, or hypertonic

Question 24

Hypotonic hyponatremia causes?

Answer 24

SIADH

Effective arterial blood volume depletion - CHF, cirrhosis, diuretics

Endocrine d/o: hypothyroid, adrenal insufficeincy

Advanced renal failure - kidneys lose ability to concentrate urine properly.

Question 25

Isotonic hyponatremia causes?

Answer 25

Pseudohyponatremia – increased serum lipids or proteins can lead to erroneous measurements of sodium levels.

Question 26

Hypertonic hyponatremia is caused by?

Answer 26

Signfiicant hyperglycemia

Mannitol, maltose, or surcrose retention

Sodium is diluted

Question 27

Clinically people are not symptomatic until about what level of sodium

Answer 27

125-130

Question 28

s/s of hyponatremia?

Answer 28

Anorexia, n/v, lethargy, disorientation, headahce, seizures.

signs: weakness, agitation, hyporeflexia, orthostatic hypotension, delirium, coma, seizure, respiratory arrest, brainstem herniation.

Question 29

How do you diagnose hyponatremia?

Answer 29

Focus on finding underlying cause

1st - BMP and serum osmolality - osmolality can further direct you to hypotonic, isotonic, or hypertonic.

If hypotonic assess volume status.

Urine osmolality and elctrolytes are helpful as well.

Other possibilities - TSH, plasma cortisol, ACTH stimulation test, brain or lung imaging.

Question 30

Acute hyponatremia occured within the last? Subacute? Chronic?

Answer 30

Acute - 24 hours

subacute - 24-48 hours

chronic - >48 hours.

Question 31

Severe hyponatremia? Moderate? mild?

Answer 31

Severe - less than 120

modertae - 121-129

mild - 130-135

Question 32

How do you treat hyponatremia?

Answer 32

Identify and treat the underlying cause

If symptomatic, even mild, - need emergency therapy of hypertonic saline.

Raise by 4-6 over a couple of hours to prevent herniation and relieve symptoms

Question 33

What happens if you raise serum sodium too fast?

Answer 33

Can lead to osmotic demyelination syndrome

AKA central pontine myelinolysis.

Question 34

Hypovolemic hyponatremic treatment?

Answer 34

Isotonic saline.

Question 35

Hypervolemic hyponatremic treatment?

Answer 35

CHF, cirrhosis: diuresis, fluid restriction, sodium restriction

renal failure: fluid restriction, dialysis, sodium restriction.

Question 36

Euvolemic hyponatremic treatment? SIADH tx?

Answer 36

Fluid restriction

SIADH - may add salt tabs and or a loop diuretic.

Question 37

What medication is used for SIADH patients that don’t respond to salt tablets or diuretics?

Answer 37

Demeclocycline

S/e: renal toxicity - esp for cirrhosis, can cause nephrogenic DI, intracranial hypertension.