Sodium level decreases 1.6 mEq/L per each 100 mg/dL increase in serum glucose.

TBW is approximately 60% in men and 50% to 55% in women.
TBW is lower in obese (50%) and higher in lean individuals (70%).


BUN/Cr (S) ratio > 20 (fraction) indicates prerenal causes.
BUN/Cr (S) ratio < 10 (fraction) indicates renal causes.