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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
Na
= (U
[Na + ]
× P
[Cr]
)/(P
[Na + ]
× U
[Cr]
) × 100
(U
[Na + ]
and P
[Na + ]
in mmol/L; U
[Cr]
and P
[Cr]
in mg/dL)