click below
click below
Normal Size Small Size show me how
Formulas
alculated Chemistry Values
Value | Calculation | Normal Range | Clinical significance |
---|---|---|---|
BUN:Creatinine ratio | BUN/Creatinine | 12-20 | ↑ in pre or postrenal azotemia |
Creatinine clearance | UxVx1.73/PxSx1440 U-urine creatinine; P-plasma creatinine; V-urine volume in ml per 24hr; S-body surface | ♂ 97-137 ml/min; ♀ 88-128 ml/min | ↑ in renal disease |
Friedewald formula | LDL=Total cholesterol -HDL-(tryglicerides/5) | <130 mg/dL | ↑ in coronary artery disease; not valid if tryglicerides >400 mg/dL |
Calculated Osmolality | 1.86xNa + (glucose/18) + (BUN/2.8) + 9 | 275 - 295 mOsm/kg | ↑ in dehydration; uremia; diabetes; alcohol intoxication ↓ in excessive H2O intake |
mg/dL into mmol/L | mmol/L =(mg/dL)x 10 x valence / MW | ||
A:G ratio | albumin/(total protein -albumin) | 1-2.5 | Reversed ratio - multiple myeloma, liver disease |
Anion Gap | (Na+K)-(Cl+CO2) | 10-20 mEq/L | ↑ in renal failure, diabetic and lactic acidosis, drugs, toxins, lab. error |