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Assessing urine ammonium concentration by urine osmolal gap in chronic kidney disease
Author(s) -
Fujimaru Takuya,
Shuo Takuya,
Nagahama Masahiko,
Taki Fumika,
Nakayama Masaaki,
Komatsu Yasuhiro
Publication year - 2021
Publication title -
nephrology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 61
eISSN - 1440-1797
pISSN - 1320-5358
DOI - 10.1111/nep.13937
Subject(s) - medicine , kidney disease , urine , creatinine , dialysis , renal function , urine osmolality , urology , excretion , acute kidney injury , endocrinology , gastroenterology
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‐NH 4 + ) is the crucial component of renal acid excretion, U‐NH 4 + concentration is not routinely measured. To estimate U‐NH 4 + , urine osmolal gap (UOG = urine osmolality − [2(Na + + K + ) + urea + glucose]) is calculated and the formula (U‐NH 4 + = UOG/2) has traditionally been used. However, the usefulness of this formula is controversial in CKD patients. We assessed the relationship between U‐NH 4 + and UOG in patients with CKD. Blood and spot urine samples were collected in 36 patients who had non‐dialysis‐dependent CKD. The mean ± SD age of patients was 72.0 ± 14.8 years, and the mean ± SD serum creatinine and U‐NH 4 + were 2.7 ± 2.3 mg/dl and 9.3 ± 9.2 mmol/L, respectively. A significant relationship was found between UOG/2 and U‐NH 4 + ( r = .925, p < .0001). U‐NH 4 + estimated using the UOG was on average higher by 4.7 mmol/L than the measured one. Our results suggested that UOG could be a useful tool in clinical settings, especially in patients with moderate to severe CKD.