Hypernatremia and hypo Flashcards
Hypernatremia is defined as levels above? Most often from?
Elevated serum sodium above 145
Most often from water depletion
Elderly patients with decreased thirst and acess to fluids are at higher risk of what?
Hypernatremia
What is hypernatremia almost always from?
Almost always from inadequate fluid intake or excess water loss. - think about elderly, dementia patients who forget to drink fluids.
Water can be lost in the urine in what three ways?
Osmotic diuresis
Diabetes insipidius (central or nephrogenic)
Diuretics can waste water and or sodium - Think thiazide Diuretics.
Hypervolemic hypernatremia is most likely caused by?
Iatrogenic from hypertonic saline or dialysis
Hyperaldosteronism.
Hypovolemic hypernatremia is most likely caused by?
Renal losses from renal disease or diuretics - thiazide.
Extrarenal losses - vomiting/diarrhea.
Euvolemic hypernatremia is most likely caused by?
Hypodipsia - decreased thirst - hypothalamus lesion
diabetes insipidus.
What are clinical symptoms of hypernatremia? Early, Next?
Early sx: anorexia - restlessness or n/v
Next: progressive AMS: lethargy or irritability 1st, then stupor or coma.
Neurologic signs of hypernatremia?
Twitching, hyperreflexia, ataxia, tremor, seizures.
S/S of dehydration?
Dry MM, tenting/poor skin turgor, lack of tears, decreased salivation, tachycardia, hypotension, oliguria/anuria.
Acute vs Chronic hypernatremia. How long has chronic been present? What is acute more likely to provoke?
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
How do you diagnose hypernatremia?
Cuase is usually obvious from history
BMP - sodium above 145
If hypernatremia etiology is unclear what should you order?
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.
What is the treatment for hypernatremia?
Give dilute fluids to correct the deficit and replace ongoing losses.
Treatment of chronic hypernatremia?
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.
In chronic hypernatremia you don’t want to lower sodium by more than what in a 24 hour period?
Lower serum sodium by max of 10 over a 24 hour period.
How do you treat acute hypernatremia?
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.
Mortality rate of hypernatremia?
40-60% - many with underlying severe diseases
What is the most common electrolyte disorder seen in hospitalized patients?
Hyponatremia
Hypervolemic hyponatremia is caused by?
Fluid overload - water is either added or retained –> the amount of sodium in the serum is diluted.
CHF, cirrhosis, IVF, nephrotic syndrome.
Hypovolemic hyponatremia is caused by?
Water and sodium is lost (but more sodium than water)
Renal losses - diuretics, especially thiazides.
Extrarenal losses - diarrhea, sweating, blood loss, fluid shifts.
Euvolemic hyponatremia is caused by (5)
Adrenal insufficiency
Polydipsia - primary or psychogenic (hypothalamus lesions)
Hypothyroidism
Syndrome of inappropriate antidiuretic hormone (SIADH) - brain or lung issue
Reset osmostat.
How do you classify by tonicity?
Hypotonic, isotonic, or hypertonic
Hypotonic hyponatremia causes?
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.
Isotonic hyponatremia causes?
Pseudohyponatremia – increased serum lipids or proteins can lead to erroneous measurements of sodium levels.
Hypertonic hyponatremia is caused by?
Signfiicant hyperglycemia
Mannitol, maltose, or surcrose retention
Sodium is diluted
Clinically people are not symptomatic until about what level of sodium
125-130
s/s of hyponatremia?
Anorexia, n/v, lethargy, disorientation, headahce, seizures.
signs: weakness, agitation, hyporeflexia, orthostatic hypotension, delirium, coma, seizure, respiratory arrest, brainstem herniation.
How do you diagnose hyponatremia?
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.
Acute hyponatremia occured within the last? Subacute? Chronic?
Acute - 24 hours
subacute - 24-48 hours
chronic - >48 hours.
Severe hyponatremia? Moderate? mild?
Severe - less than 120
modertae - 121-129
mild - 130-135
How do you treat hyponatremia?
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
What happens if you raise serum sodium too fast?
Can lead to osmotic demyelination syndrome
AKA central pontine myelinolysis.
Hypovolemic hyponatremic treatment?
Isotonic saline.
Hypervolemic hyponatremic treatment?
CHF, cirrhosis: diuresis, fluid restriction, sodium restriction
renal failure: fluid restriction, dialysis, sodium restriction.
Euvolemic hyponatremic treatment? SIADH tx?
Fluid restriction
SIADH - may add salt tabs and or a loop diuretic.
What medication is used for SIADH patients that don’t respond to salt tablets or diuretics?
Demeclocycline
S/e: renal toxicity - esp for cirrhosis, can cause nephrogenic DI, intracranial hypertension.
