Sodium Disorders

Source:  Sodium Disorders    Tag:  myeloproliferative disorder symptoms
§  Serum Na+ concentration less than 135 mEq/L
§  Can occur with low, normal, or high total body Na+ ; hyponatremia requires the presence of too much water relative to the quantity of total body Na+
§  Signs & symptoms are dt swelling of CNS  2ry to  ↓ serum osmolality & intracellular water shift

Signs & symptoms of hyponatremia
[Na+ ] = 125–135 mEq/L
Muscle cramps

[Na+ ] = 120–125 mEq/L

[Na+ ] < 120 mEq/L
Cheyne-Stokes respirations

Diagnosis and evaluation
Determine osmolality :
-         Normal (280-295 mOsm/kg)
a.      Pseudohyponatremia : hyperlipidemia, hyperproteinemia e.g. MM
b.      Iso-osmolar infusion of non-Na containing solution
-         High (>295 mOsm/kg)
a.      Hyperglycemia
b.      Hyperosmolar infusion of non-Na containing solution
-         Low (<280 mOsm/kg): Determine volume status
a.      Hypovolemia:
§  Suggestive findings: hypotension, tachycardia, dry mucous membranes, skin tenting
§  Extra-renal losses : urinary Na < 10 mEq/L (↑Na reabsorption by the kidney) à diarrhea, vomitig, 3rd  spacing e.g. pancreatitis  w/ pseudocysts, burns, small bowel obstruct.
§  Renal losses: : urinary Na > 20 mEq/L à diuretics, adrenal insufficiency, RTA
§  GI and 3rd-space losses cause hyponatremia if replacement fluids are hypotonic compared with losses
b.     Hypervolemia:
§  Suggestive findings : edema, crackles,  ↑JVP, S3
§  Urinary Na < 10 mEq/L : CHF, cirrhosis, nephrotic synd
§  Urinary Na > 20 mEq/L : acute & chr. kidney disease
c.      Euvolemia:
§  Hypothyroidism, SIADH (Urinary Na > 20 mEq/L)
§  Free water intoxication (Urinary Na < 10 mEq/L): excessive intake of water esp. in the setting of proloned exercise
-         Hypovolemic hypo-osmolar: Isotonic saline
-         Hypervolemic hypo-osmolar: Fluid restriction, diuresis, dialysis
-         Euvolemic hypo-osmolar: Fluid restriction, consider use of V2  ADH receptor antagonists (e.g. tolvaptan)
-         With Severe CNS symptoms :↑ Na+ concentration 1 to 2 mEq/L/hr with 3% saline until symptoms abate
-          Rate of correction :
a.      Chronic hyponatremia (>24–48 hours): Raise Na+ concentration 0.5 to 1 mEq/L/hr & no > 8 to 10 mEq/L in 24 hours
b.      Acute hyponatremia (<24–36 hours): Can raise 1 to 2 mEq/L/hr usually without the need for 3% saline unless severe CNS symptoms are present
c.      Rapid correction can lead to osmotic demyelination i.e. central pontine myelinolysis


-         Serum Na+  > 145 mEq/L
-         Thirst is the major defense against the development of hypernatremia
-         Usually requires impaired access to water
-         If free access to water is present, consider impaired thirst mechanism
-         Signs and symptoms are due to dehydration of the CNS
-         Pts may experience restlessness, irritability, lethargy, muscle twitching, hyperreflexia, spasticity, and, in severe cases, intracranial hge
-         Mostly occurs in hospitalized Pts, Elderly outpatients
-         DD :

1.      Hypervolemic: hypertonic saline, conn’s, cushing’s synd.
2.      Euvolemic : DI
3.      Hypovolemic:
o   Urinary Na > 20 mmol/l : diuretics
o   Urinary Na < 10 mmol/l : GI losses, 3rd spacing, insensible losses e.g dt fever, mechanical ventilation
-         TTT:
a.      Address underlying condition
b.      Overly rapid correction can à cerebral edema
c.      If evidence of circulatory collapse à correct hypovolemia w/ normal saline
d.     Free water deficit = TBW x [ (   ) – 1 ]

e.      Decrease serum Na+  concentration approximately 0.5 mEq/L/hr and no more than 8 to 10 mEq/L in 24 hours