Sodium Disorders

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?

1. treat underlying disorder

2. water restriction 1000-1200 mL/day

3. vasopressin receptor antagonists

4. 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?

1. treat underlying disorders

2. water restriction 1000-1200 mL/day AND salt restriction 2000 mg/day

3. loop diuretics

4. 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