In timed urine collections other than 24 hours (+/- 2 hours), the 24 hour excretion cannot be calculated due to different day time and night time excretion patterns of various analytes.
Please note: Serum creatinine is required for this calculation. Ideally, the serum creatinine should be measured within 24 hours of the urine collection period although results from up to a week beyond may be valid if renal function has been stable.
Creatinine clearance is calculated using the following equations:
Creatinine Clearance (ml/min) = (U Creat x Vol x1000) / (Serum Creat x 1440)
Creatinine Clearance (ml/sec) = (U Creat x Vol x 1000) / (Serum Creat x 86400)
where U Creat is in mmol/L, Vol is in mL, Serum Creat is in umol/L and time is 24 hour period.
