HypoNa Flashcards
Symptoms of hyponatremia usually do not develop until serum sodium level reaches? Clinical Manifestations?
Low 120s. Cerebral edema, lethargy, confusion, seizures, or coma
Most common electrolyte disturbance among hospitalized patients? Defined by?
Hyponatremia. Defined by serum sodium level less than 135
Serum osmolarity: Hypernatremia versus hyponatremia?
Always hyperosmolality
versus
hyper-, normal, or hypo-osmolality
What does it mean to have hyponatremia with hyper- or normal osmolarity?
Pseudohyponatremia.
If normal osmolarity: hyperproteinemia, hyperglycemia, Post transurethral resection of prostate
If hyperosmolar: hyperglycemia, mannitol
Hyponatremia is most commonly associated with what type of state?
Hypo osmolar state
Hyperosmolar hyponatremia is most often caused by?
Molecule that is stuck in the extracellular space and cannot cross cell membranes (Glucose, mannitol)
Hyponatremia from hyperglycemia occurs in what setting? Relationship between glucose and Na?
Uncontrolled diabetes. Each 100 increase in serum glucose leads to a 1.6 decrease in serum sodium
Surgical procedure that is a common cause of hyponatremia because of fluid used in intra- operatively?
Transurethral resection of the prostate because of the large volume of mannitol irrigation
Pseudohyponatremia?
Artifact of measurement where high-protein levels or high lipid levels interfered with serum sodium level (Not an issue with current laboratory techniques)
Hypotonic hyponatremia occurs because of?
Water gain from an attempt to maintain effective circulating volume or in SIADH
(Caused from impairment of free water excretion - Difficult to overwhelm kidney excretion ability simply with excessive intake)
In hypovolemia, urine sodium level should be? Otherwise?
Less than 10-20 mmol/L. Otherwise kidneys do not have the ability to retain sodium normally
Causes of hypervolemia? Mech?
CHF, liver cirrhosis, nephrotic syndrome.
Excess of sodium and water but baroreceptors perceive hypoperfusion. Leads to an increasing ADH and retention of more water
Renal failure can lead to hypotonic hyponatremia because? Tx?
Inability to excrete dilute urine. diuretics
Patient with euvolemic hyponatremia. Next step?
Measure urine osmolarity to determine if kidney is excreting free water normally (less than 100 mmol/L)
Patient with euvolemic hyponatremia with maximally dilute urine. Diagnosis?
Central polydipsia (kidney is handling free water normally but its capacity for excretion has been overwhelmed)
Patient with euvolemic hyponatremia with less than maximally dilute urine. Ddx?
Hypothyroidism, adrenal insufficiency or SIADH
Effect of thyroid hormone and cortisol on free water excretion?
Increases free water excretion (deficiency causes water retention)
Isolated cortisol deficiency can mimic? (Regarding Na)
SIADH
Patients with adrenal insufficiency present with? (Vitals, labs, symptoms, exam findings)
Vitals: low BP
Labs: hyperkalemia and acidosis Sx: fatigue, weight loss
Exam: hyperpigmentation
Euvolemic hyponatremia is most commonly caused by? Occurs in what settings?
SIADH. Pulmonary disease, CNS disease, pain, post operatively, paraneoplastic syndrome
In order to be diagnosed with SIADH, need?
- Hypoosmolar but euvolemic,
- Urine that is not maximally dilute (osmolarity>150)
- urine sodium more than 20
- normal adrenal thyroid function
Laboratory tests that will suggest SIADH? Tx?
Low BUN and low uric acid levels. Water restriction.
SIADH patients with neurological symptoms should be treated with?
Hypertonic (3%) saline (not NS)
When using hypertonic saline solution, if concerned about volume overload, administer i fusion with?
Furosemide or another loop diuretic. Diuretic causes excretion of hypotonic urine resulting in a greater portion of sodium than water being retained
Central Pontine myelinolysis caused by? Can lead to?
Rapid correction of hyponatremia. May cause quadriplegia, pseudobulbar palsies, locked in syndrome
Avoid osmotic cerebral demyelination by?
Not correcting the serum sodium concentration faster than .5 to 1 mEq/hr
Why does hyponatremia occur after surgery?
Operations increase AVP
Hypovolemic patients with hyponatremia should be treated with?
0.9 saline solution
Euvolemic patients with asymptomatic hypernatremia should be treated with?
Fluid restriction
HyperNa patients with severe symptoms such as coma or seizures should be treated with?
Hypertonic (3%) saline
