Assessing urine ammonium concentration by urine osmolal gap in chronic kidney disease

Acidemia is one of the risk factors for end-stage kidney disease and increases the mortality rate of patients with chronic kidney disease (CKD). Although urinary ammonium (U-NH4+ ) is the crucial component of renal acid excretion, U-NH4+ concentration is not routinely measured. To estimate U-NH4+ , urine osmolal gap (UOG = urine osmolality - [2(Na+ + K+ ) + urea + glucose]) is calculated and the formula (U-NH4+ = UOG/2) has traditionally been...