Question

Calculate the estimated GFR given the following information: plasma creatinine: 3.8mg/100mL urine creatinine: 1.35mg/mL urine volume (collected over 12 hours): 450mL

Answer 1

Step 1:

Calculation of estimated GFR formula is

GFR = (Volume of urine mL/min X urine creatinine (mg/dL)) / Serum creatinine (mg/dL)

Step 2:

Calculate volume of urine per min

Volume of urine collected over 12 hrs = 450mL

Volume of urine per minute = 450 / 12 X 60

= 0.625

Step 3:

Calculate serum creatinine in mg/dL

Serum creatinine = 3.8mg/100mL

1mg/mL = 100mg/dL

Therefore 3.8 mg/100mL = 3.8mg/dL

Step 4:

Calculate urine creatinine in mg/dL

Urine creatinine = 1.35mg/mL

Therefore 1.35 X 100 = 135mg/dL

step 5:

By sustituting into the formula,

GFR = 0.625 X 135 / 3.8

= 22.2mL/min.

The estimated glomerular filtration rate is 22.2mL/min.