The serum phenytoin for a patient with end stage renal disease and hypoalbuminemia can be normalized using a modification of the Sheiner-Tozer equation described in the previous section.
estimated total serum phenytoin in mg/L if serum albumin were normal =
= (measured total serum phenytoin in mg/L) / ((0.1 * (serum albumin in g/dL)) + 0.1)
Possible modification: Since this equation is similar to the Sheiner-Tozer equation for hypoalbuminemia - differing only in the use of 0.1 rather than 0.2 - I wonder if it could be possible to modify the equation to take into account variation in renal function as follows:
estimated total serum phenytoin in mg/L if serum albumin were normal =
= (measured total serum phenytoin in mg/L) / ((X * (serum albumin in g/dL)) + 0.1)
X =
= ((decimal fraction of renal function) * 0.1) + 0.1
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