Patients with chronic kidney disease who have low levels of ammonium in their urine may be at high risk of the disease progression or death, researchers have warned.A study by US researchers showed that patients with the lowest levels of urine ammonium excretion had a 46 per cent higher risk of dying or needing dialysis, and those with intermediate levels had a 14 per cent higher risk, irrespective of serum bicarbonate concentration. In addition, those with low ammonium excretion had a 2.6-fold higher risk of developing acidosis -- a condition where the body's fluids contain too much acid -- within one year, the researchers said."These results suggest that low urine ammonium excretion identifies individuals at high risk of chronic kidney disease progression or death irrespective of the serum bicarbonate concentration," said Kalani Raphael from the University of Utah in the US. "Overall, acid levels in the urine provide important information about kidney health above and beyond acid measurements obtained from the blood," Raphael added, in the paper appearing in the Journal of the American Society of Nephrology (JASN).In order to maintain normal organ function, it is imperative to keep the body's pH level in balance -- measured using the bicarbonate levels in the blood.However, this measurement may only partly indicate whether the body is having trouble maintaining its acid-base balance or not, because the kidneys are important for eliminating acid in the urine.Thus, the team looked to see if urine levels of ammonium may be a better indicator of acid accumulation in the body. Their analysis included 1,044 individuals with chronic kidney disease.