Ch04-9781975113285

1 2   INTERNSHIP SURVIVAL GUIDE

• Um, yeah, like you’re going to calculate those exponents in your head. Obviously, this is too complicated without a calculator. • If you care, MDRD stands for Modification of Diet in Renal Disease (study). • MDRD is fairly accurate for patients with known chronic kidney disease and who are not hospitalized. Estimated (The Chronic Kidney Disease Epidemiology Collaboration) eGFR = 141 × min (SCr/ κ , 1) α  × max (SCr/ κ , 1) −1.209  × 0.993 age

× 1.018 ( if female ) × 1.159 ( if black ) ( eGFR in mL/min per 1.73m 2 , Cr in mg/dL )

• Again, ain’t no way anyone can calculate that in his/her head. • More accurate when GFR is close to normal. Measured (24-h) CrCl = (U [Cr]  × U volume )/(P [Cr]  × 24 × 60) ( Cr in mg/dL, volume in mL, and time in min )

CORRECTED SERUM CALCIUM

Corrected serum Ca = [Ca +2 ] +  [ 0.8 × (4.0  −  [albumin]) ] ( [Ca +2 ] in mg/dL, albumin in g/d )

CORRECTED SERUM SODIUM

Corrected serum Na = [Na + ] +  [ 0.016 × ([glucose]  −  100) ] ( [Na + ] in mmol/L, [glucose] in mg/dL )

FRACTIONAL EXCRETION OF SODIUM

FE

 = (U

 × P

)/(P

 × U

) × 100

Na

[Na + ]

[Cr]

[Na + ]

[Cr]

(U

and P

in mmol/L; U

and P

in mg/dL)

[Na + ]

[Na + ]

[Cr]

[Cr]