Ans. a (Altered sensorium) (Ref. Harrison's - 18th/pg. Ch. 45).Hyponatremia may be due to water excess, diabetes, lipidemia etc. Drugs known to release ADH will cause dilutional hyponatremia include morphine, tricyclics, nicotine, NSAIDs, etc. The individual present with confusion, anorexia, lethargy and cramps. When sodium drops abruptly, seizures, hemiparesis and coma can develop.CLINICAL FEATURES OF HYPONATREMIA# The clinical manifestations of hyponatremia are related to osmotic water shift leading to increased ICF volume, specifically brain cell swelling or cerebral edema.# The symptoms are primarily neurologic.# Patients may be asymptomatic or complain of nausea and malaise.# As the plasma Na+ concentration falls, the symptoms progress to include headache, lethargy, confusion, and obtundation.# Stupor, seizures, and coma do not usually occur unless the plasma Na+ concentration falls acutely below 120 mmol/L or decreases rapidly.# Loss of Na+ and K+, followed by organic osmolytes, from brain cells decreases brain swelling due to secondary transcellular water shifts (from ICF to ECF).# The net effect is to minimize cerebral edema and its symptoms.Composition of World Health Organization Oral Rehydration Solution (ORS) A,BConstituentConcentration, mmol/LNa+90K+20Cl-80Citrate10Glucose110Also know:*SLADH is characterized by hypotonic hyponatremia with euvolemia. Low plasma osmolality (<280 mOsm/Kg) with high urine osmolality (>100-150 mOsm/Kg) in suspected patients is diagnostic.* Pneumonia, hyponatremia and diarrhea are almost classic for Legionella.* Under most physiologic conditions, sodium, urea, and glucose generate the osmotic pressure of blood. Plasma osmolality is calculated according to the following expression: Posm = 2Na+ + Glu + BUN (all in mmol/L), or, using conventional laboratory values in which glucose and BUN are expressed in milligrams per deciliter: Posm = 2Na+ + Glu/18 + BUN/2.8. The calculated and determined osmolality should agree within 10-15 mmol/kg H20. When the measured osmolality exceeds the calculated osmolality by >15-20 mmol/kg H20, one of two circumstances prevails. Either the serum sodium is spuriously low, as with hyperlipidemia or hyperproteinemia (pseudohyponatremia), or osmolytes other than sodium salts, glucose, or urea have accumulated in plasma.