The molecular weight of urea is 60.06 g. 1 gram of urea = 16.65 mmol.
Convert a measurement of urea nitrogen to urea (multiply mg/dL urea nitrogen by 0.357 to get urea in mmol/L)
Specimen: 24-hour urine
Parameters:
(1) urea excretion in mmol/day
(2) sodium excretion in mmol/day
(3) potassium excretion in mmol/day
(4) ammonia excretion in mmol/day
(5) measured urine osmolality (in mOsm per kilogram water)
excretion per day =
= (concentration in mmol/L) * (liters of urine per day)
urine solute load in mOsm/day =
= (urea) + (2 * (sodium)) + (2 * (potassium)) + (2 * (ammonia))
The estimated urine solute load should be close to the measured urine osmolality.
The accuracy of the calculation depends on having an accurate 24-hour urine.
