Hypo Nat Re Mia

Hyponatremia < 130 • ↑ or ↓ in serum Na → ↑ & ↓ in ECV & PV, so it’s result from excess or deficit of water • total body Na regulated by aldosterone and ANP, where serum [Na] by ADH • S/S depend on the rate and severity of ↓ of Na: loss of apatite, N&V, cramps, weakness, ↓LOC, coma and seizure • Acute CNS S/S is due to cerebral edema • What is the serum osmolality see figure • Cerebral salt wasting syndrome, mediated by BNP, independent of SIADH, risk head trauma, tumor, SAH, and infection • SIADH → see other card • Rx < 120 with 3% NS @ 1-2 ml/kg/hr to ↑ serum Na 1-2 mEq/l/hr only for few hrs, not more than 25 mEq/l/48 hrs • Rapid correction → abrupt brain dehydration→ central pontine myelinolysis mild (transient behavioral disturbances or seizures) to severe (including pseudobulbar palsy and quadriparesis).Within 3 to 4 weeks of the clinical onset of the syndrome, areas of demyelination are apparent on MRI, risk factors (alcoholism, poor nutritional status, liver disease, burns, and hypokalemia) , cerebral hemorrhage and CHF • Once serum Na > 120 fluid restriction is enough , Also treat the underlying causes To calculate the net water loss necessary to ↑ [Na+] in hyponatremia, use the following equation:

Current [Na+] × current TBW = desired [Na+] × desired TBW→ TBW= 0.6x wt