Electrolyte imbalance Flashcards
Mild/chonic hyponatremia
Asymptomatic, impaired attention, altered gait, fall risk (slow firing neuron’s)
Serum osmolality calc
2*[Na] + [glucose] + BUN
Moderate to severe hyponatremia
GI upset, headache, lethargy, altered mental status, seizures, respiratory assest
Severity depends on rate of Na loss
SrNa <135 mmol/L
Sr Osm <280 mOsm/L (low)
postural hypotension
Urine Osm >450mOsm/kg (high)
Una <20 mEq/L
Sodium loss from extra renal sources or Urine Na would be higher. Urine is still very concentrated to try and retain water. Look for sweating, vomiting
SrNa <135 mmol/L
Sr Osm <280 mOsm/L (low)
postural hypotension
Urine Osm >450mOsm/kg (high)
Una >20 mEq/L
Sodium loss in kidneys, check for diuretics or adrenal insufficiency and loss of aldosterone secretion
SrNa <135 mmol/L (low)
Sr Osm <280 mOsm/L (low)
Urine Osm <100 mOsm/kg (low)
Una <20 mEq/L
Euvolemic hyponatremia
primary polydipsia is likely, from diabetes
SrNa <135 mmol/L (low)
Sr Osm <280 mOsm/L (low)
Urine Osm >100 mOsm/kg
Una >20 mEq/L
Euvolemic hyponatremia
hypothyroidism, hypocortisolism, kidney failure, SIADH
SrNa <135 mmol/L (low)
Sr Osm <280 mOsm/L (low)
Edema
Urine Osm >100 mOsm/kg (low)
Una <20 mEq/L
Fluid over load is leading to hypervolemic edema and diluted electrolytes in the blood. Organ failure of heart, liver or kidney is likely
SIADH
inappropriate antidiuretic hormone
Can be from tumors, CNS disorder. Basically throws away Na but keeps fluids
SIADH drugs
Tricyclic Antidepressants, opioids, nicotine, bromocriptine, NSAIDS, acetaminophen
Pseudohyponatremia
If the patient has elevated proteins or cholesterol in the blood this can reduce the fraction of Na in the sample causing it to look like hyponatremia
Lab tests for Na imbalance
Serum sodium concentration
plasma osmolarity
urine analysis (osmoses and [Na])
glucose, lipid, SrCr, thyroid, ALT + AST and troponin to check for organ failure if hypervolemic
Na increase
No faster than 6-12 mmil/L in 24 hours to prevent demyelination
hyponatremia treatment
Hypertonic 3% saline for very serious
0.9% Saline to correct vascular volume and prevent ADH release to prevent Na loss
Oral replacement
Sx should go away after 5% increase or reaching 120mmol/L
Hypervolemic treatment
Underlaying causes
Fluid restriction to pull water out of extracellular space (1-1.2L/day)
Sodium restriction (1-2g/day) prevent water retention
Vasopressin antagonists (tolvaptan) if very bad V2 receptor antagonist (prevents water reabsorption)
Euvolemic treatment
Underlaying cause
SIADH, hormone imbalance or polydipsia
tolvaptan if really bad
Fluid restriction 1-1.2ml/day
hypernatremia picture
Serum Na >145 or >160 if severe
weakness, lethargy, restlessness, irritable, twitching (neruon’s are excited)
severe can lead to seizures and coma
SrNa >145
BP is low
Hypovolemic
water loss is fast than Na loss via sweating, diarrhea or vomiting
Christ response can usually solve this
hypovolemic hypernatremia treatment
If stable use oral fluids with salt
If unstable use normal saline
200-300ml/h for adults
10-20ml/kg/h for kids
change to 1/2 saline once stable
SrNa >145
BP is normal
water loss is crazy >3L per day
diabetes insipidus is most common cause
central euvolemic hypernatremia
Caused by inability to produce vasopressin from tumour, head trauma
Nephrogenic euvolemic hypernatremia
Renal tubules don’t respond to vasopressin (Lithium, hypokalemia, hypercalcemia or kidney disease) can cause this slowly
Nephrogenic euvolemic hypernatremia treatment
Stop drug and correct other ion imbalances
limit Na intake and start thiazide diuretic to reduce Na
SrNa >145
BP is high
sodium overload from 3% saline overcorrection or excessive oral intake
Give D5W (little vascular fluid retention) and loop diuretic to lower Na
hypochloremia
Usually follows Na and will be lost during vomiting or diarrhea, can lead to metabolic alkalosis
Hyperchloremia
associated with metabolic acidosis and hypernatremia
