Sodium Disturbances Flashcards
What is the normal sodium concentration?
Na 135-145
Normal urine osmolality
<100mosm/kg
Normal serum osmolality
285 mosm/kg
What is the pathophysiological response to plasma hypotonicity
Sensed by hypothalamus - reduces synthesis of ADH - Diminished ADH in circulation - Fewer water channels in the kidney - creates water impermeable conduit - prevents water reabsorption - allows excretion of dilute urine
Pathophysiological response to plasma hypertonicity
Higher concentration of ADH - higher water permeability - excretion of concentrated urine
Non-osmotic causes of vasopressin release
Baroreceptors, Pain, stress, nausea, hypoxia, hypercapnea, medications
What are the three types of hyponatremia
Isotonic, hypotonic, hypertonic
Low Na+ and normal serum osmolarity
Isotonic hyponatremia
Causes of isotonic hyponatremia
Artifact, hypertriglyceride, paraproteinemia
Low Na+ and high serum osmolarity
Hypertonic Hyponatremia
Low Na+ and decreased serum osmolarity
Hypotonic Hyponatremia
What are the three types of hypotonic hyponatremia?
Euvolemic, Hypovolemic, Hypervolemia
Hypotonic Euvolemic hyponatremia definition
Low Na+, low osmolarity, with clinically normal volume
Causes of Euvolemic Hypotonic Hyponatremia
SIADH
Hypothyroidism
Glucocorticoid insufficiency
Medications
Reset osmstat syndrome
What is the pathophysiology behind hypotonic hypovolemic hyponatremia
Low Na+, low osmolarity, clinically low volume
Impaired urinary diluting mechanism
Causes of hypovolemic hypotonic hyponatremia
Hemhorrage, vomiting, diarrhea, diuretics, renal sodium wasting, cerebral salt wasting
What is the normal level of urine sodium concentration and what do we see in hypotonic hypovolemic, hyponatremia
Normal: 40-220
Abnormal: <10
Causes of hypotonic Hypervolemic hyponatremia
Renal failure
CHF
Cirrhosis
Nephrotic syndrome
Compromised renal diluting ability
Serum Osmolality 280-295 with hyponatremia
Pseudohyponatremia
Serum osmolality >295 with hyponatremia
Hypertonic hyponatremia
Osmolarity <280 with hyponatremia
Hypotonic hyponatremia
What does a urine osmolarity <100 and >100 indicate
<100: primary polydipsia or potomania
>100: assess patient volume status
What is the goal Na+ correction rate and limit for correction?
Rate of correction: 4-6 mEq/L/24hrs
Limit: 6-8 meq/L/24 hours
What is the risk of rapid sodium correction?
Osmotic demyelination syndrome
How to correct chronic hyponatremia (>48hrs)
Slow, avoid rapid shifts
Severely chronic are at high risk for demyelination
In this case give DDAVP and dextrose 5%
Treatment for mild to moderate hypotonic hyponatremia
Treat underlying cause
When can sodium be corrected quickly
Post-op acute changes or acute seizures
How to treat severe hyponatremia with seizures
% hypertonic saline 100mls over 10mins
Repeat only twice PRN
Check BMP q1-2 hours
Only treat until symptoms subside
How to treat hypertonic hyponatremia
Treat underlying condition
Most often HHS
Hypotonic euvolemic hyponatremia treatment
Treat underlying condition
If acute can be corrected quickly
Hypotonic hypovolemic hyponatremia treatment
Fluid resuscitation with isotonic fluid, hold diuretics
Hypotonic Hypervolemic Hyponatremia treatment
Loop diuretics, V2 receptor agonist (Tolvaptan, do not give in cirrhosis)
Management for cerebral salt wasting
Hypertonic solution
SIADH treatment plan
Withhold medications, fluid resuscitation, increase solute intake (salt tabs), diuretics
How to treat psychogenic polydipsia
Fluid restriction
What is the most common cause of sustained hypernatremia
Hospital setting fluid administration
S/s of hypernatremia
Weakness, lethargy, confusion, seizures, coma, dehydration, orthostatic hypotension, oliguria, change in LOC, osmotic cerebral demyelination
What are the main causes of euvolemic hypernatremia
Pure water loss, Central DI, Nephrogenic DI
What is the primary characteristic lab findings for DI
Hypernatremia with urine osmo <250
S/s of hypovolemic hypernatremia
Orthostatic hypotension, tachycardia, decreased organ perfusion
Common causes of hypovolemic hypernatremia
Loss of GI fluids, diuretics, vigorous exercise
If the Cl is <10 then it could be cutaneous or GI causes, extrarenal
Causes and signs and symptoms of Hypervolemic hypernatremia
Administration of hypertonic sodium salts
S/S: hypertension, edema, CHF
Treatment of hypernatremia fluid management
Goal to lower Na+ by <10 mmols/L/day, BMP q4-6hrs
D5% if unable to swallow
0.45% saline or isotonic
Avoid sterile water can cause hemolysis
Hypovolemic Hypernatremia treatment
Isotonic fluid then switch to hypotonic once volume resuscitation is complete
Euvolemic Hypernatremia treatment
Water ingestion or 5% Dextrose, diuretics
If CDI suspected give DDAVP
NDI suspected give thiazide diuretic with COX inhibitor
Hypervolemia Hypernatremia treatment
D5%, loop diuretics, Dialysis
