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What are disorders of sodium truly?
disorders of water
normal sodium range
135-145 mEq/L
Mild hyponatremia range
125-135 mEq/L
Moderate hyponatremia range
120-125 mEq/L
Severe hyponatremia range
< 120 mEq/L and/or presence of neurologic complications
What are hyponatremia symptoms dependent upon?
[Na] and rate of change of [Na]
What kind of neurological changes occur with hyponatremia?
headache → confusion → lethargy → seizures → coma
What is isotonic hyponatremia also known as?
pseudohyponatremia
What is isotonic hyponatremia?
low serum [Na] with normal measured serum osmolality
What causes isotonic hyponatremia?
hyperlipidemia or hyperproteinemia
How do you treat isotonic hyponatremia?
repeat labs!
What is hypertonic hyponatremia?
low serum [Na] with increased measured serum osmolality
What causes hypertonic hyponatremia?
hyperglycemia
How do you correct sodium for hyperglycemia?
measured Na + 1.6 x (every 100 mg/dL glucose >100)
How do you treat hypertonic hyponatremia?
reduce serum glucose and recheck sodium
What does the corrected sodium represent?
what the patient’s serum sodium will be after blood glucose is corrected to 100 mg/dL
What is hypotonic euvolemic hyponatremia?
increased total body water relative to no change in Na
What are the causes of hypotonic euvolemic hyponatremia?
SIADH (syndrome of inappropriate antidiuretic hormone
Drug induced SIADH
Psychogenic polydipsia
What is syndrome of inappropriate antidiuretic hormone?
overactivity of ADH leads to concentrated urine and excess free water in ECF
How do you treat hypotonic euvolemic hyponatremia?
treat underlying disorder
water restriction 1000-1200 mL/day
vasopressin receptor antagonists
sodium chloride + loop diuretic
What is psychogenic polydipsia?
intake >20L free water per day
What drugs could cause drug-induced hyponatremia?
SSRIs: sertraline, escitalopram, paroxetine, venlafaxine, duloxetine, etc
Carbamazepine
Opiates
What is demeclocycline?
a vasopressin antagonist that induces nephrogenic diabetes insipidus which blocks AVP at collecting duct
What is the dose od demeclocycline?
300 mg PO BID-QID
What risks are associated with demeclocycline?
renal tubular damage and AKI
What patients should you avoid giving demeclocyline?
children under 8 & pregnant women (due to bad tooth development)
What is conivaptan?
an INTRAVENOUS V1 and V2 receptor antagonist
What is the indication for conivaptan?
acute euvolemic hyponatremia
What is the brand name of Tolvaptan?
Samsca <3
What is tolvaptan?
a V2 receptor antagonist
What is the indication for tolvaptan?
hyper and euvolemic hyponatremia due to HF, cirrhosis, or SIADH; autosomal dominant polycystic kidney diseaseCYP
What is tolvaptan a substrate of?
CYP3A4 and p-glycoprotein
What is the dose for tolvaptan?
15-60 PO QD
What are the adverse effects of tolvaptan?
thirst, polyuria, constipation
What is the BBW for tolvaptan?
hepatotoxicity
What is hypotonic hypervolemic hyponatremia?
INCREASED total body water relative to sodium increase
What are the causes of hypotonic hypervolemic hyponatremia?
cirrhosis, HF, nephrotic syndrome
How do you treat hypotonic hypervolemic hyponatremia?
treat underlying disorders
water restriction 1000-1200 mL/day AND salt restriction 2000 mg/day
loop diuretics
V2 receptor antagonist
What is hypotonic hypovolemic hyponatremia?
decreased total body water relative to DECREASED sodium
What is the cause of non-renal hypotonic hypovolemic hyponatremia?
GI losses such as diarrhea/vomiting; urinary Na < 20 mEq/L
What is the cause of renal hypotonic hypovolemic hyponatremia?
thiazide diuretics; urinary Na > 20 mEq/L
How do you treat hypotonic hypovolemic hyponatremia?
0.9% sodium chloride— replaces fluid and sodium
What can rapid correction of hyponatremia cause?
osmotic demyelination syndrome (central pontine myelinolysis)
True or False: Osmotic demyelination syndrome is reversible
FALSE
What is the first goal when correcting hyponatremia?
stop symptoms and prevent seizures
What is the second goal when correcting hyponatremia?
correct [Na] to normal range
What is the maximum sodium correction rate?
6-8 mEq/L/day (0.25-0.5 mEq/L/hr
What is the sodium goal within the first 6-12 hours?
[Na] >120 mEq/L
What is acute, severe, hypotonic hypovolemic hyponatremia?
a rapid decline in serum [Na] < 110 mEq/L AND/OR severe symptoms (seizures)
What is used for the initial management of acute, severe, hypotonic hypovolemic hyponatremia?
SLOWLY give hypertonic saline (3% or 23.4% sodium chloride); may combine with loop diuretic to enhance free water clearance
When do you stop initial treatment of acute, severe, hypotonic hypovolemic hyponatremia?
once [Na] is >120 mEq/L pr severe symptoms resolve
What do you use to treat acute, severe, hypotonic hypovolemic hyponatremia after initial hypertonic solution?
isotonic fluids
What is hypovolemic hypernatremia?
water loss > > sodium loss
What causes hypovolemic hypernatremia?
over-diuresis; commonly loops
How does a patient with hypovolemic hypernatremia present?
orthostasis, hypotension, tachycardia, dry mucous membranes
How do you treat hypovolemic hypernatremia?
normal saline IV until BP/HR is stable, then free water replacement
What is euvolemic hypernatremia?
free water loss
What causes euvolemic hypernatremia?
diabetes insipidus
How does a patient with euvolemic hypernatremia present?
polyuria, polydipsia, lethargy, seizures
How do you treat euvolemic hypernatremia?
free water replacement; if central ADH disorder give vasopressin
What is hypervolemic hypernatremia?
sodium gain > > water gain
What causes hypervolemic hypernatremia?
sodium overload
How does a patient with hypervolemic hypernatremia present?
peripheral and pulmonary edema
How do you treat hypervolemic hypernatremia?
Free water + Loop Diuretic
What rate should free water be given in hypernatremia?
administer 50% in first 24 hours then the remaining 50% over 2-3 days; all should be infusions at about 100 mL/hr
Note 
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