Korean J Med.  1997 Jul;53(1):61-68.

Correlation of Urine Ammonium with Urine Osmolal Gap in High Anion Gap Matabolic Acidosis: Comparison to Urine Anion Gap

• Jung YY
• Han SW
• Park MS
• Kim GS
• Kim GH
• Cho YS
• Joo KW
• Han JS
• Kim SG
• Lee JS

Abstract

OBJECTIVES
Urine anion gap(UAG) and urine osmolal gap(UOG) were proposed as indirect measures of urine ammonium(NF4+). While the former is known to have its usefulness limited to hyperchloremic metabolic acidosis, the latter is reported to have its correlation with urine NE4+ in ketoacidosis. This study was undertaken to evaluate the correlation of urine NH with IJOG in high anion gap metabolic acidosis(AGMA) and to compare it with UAG.
METHODS
We measured urine NH' by enzymatic determination, UOG(=0.5 X [urine osmolality-{2 X (Na++K+)+urea+glucose)]), and UAG(=Na++K+-Cl-) in 18 patients(serum AG=24.4+/-1.6mmol/L ) with AGMA.
RESULTS
When they were grouped into those with acute disorders(n=11) and those with chronic disorder(n=7), urine Nk4+ concentration was higher (p<0.05) in the acute(35.6+/-7.7mmol/L) than in the chronic(3.8+/-0.9mmol/L) group. The UOG was higher (p<0.05) in the acute(73.2+/-18.9mmol/L) than in the chronic(6.3+/-8.7mmol/L) group, but the UAG had no difference between the two groups. When both groups of the patients were considered together, urine NH concentration correlated with the UOG (r=0.90, p<0.01), but not with the UAG. While the patients with lower urine NH4+ excretion(<30mmol/d) had the UOG<40mmol/L, those with higher urine NH' excretion(>40mmol/d) had the UOG>40mmol/L.
CONCLUSION
In contrast to the UAG, the UOG has a significant correlation with urine NH4+ in AGMA.

Keyword

Urine ammonium; Urine osmolal gap; Urine anion gap; High anion gap metabolic acidosis

MeSH Terms

Acid-Base Equilibrium*
Acidosis*
Ammonium Compounds*
Humans
Ketosis