Impact of pH on Urine Chemistry Assayed on Roche Analyzers.

BACKGROUND: The pH may impact the concentration of certain urinary parameters, making urine pre-treatment questionable. METHODS: 1) Determining the impact of pH in vitro on the urinary concentration of chemistry parameters assayed on Roche Modular analyzers. 2) Evaluating whether concentrations depended on pH in non-pretreated urines from patients. RESULTS: 1) The optimal urinary pH values for each measurement were: 6.3 ± 0.8 (amylase), < 5.5 (calcium and magnesium), < 6.5 (phosphorus), > 6.5 (uric acid). Urinary creatinine, sodium and urea concentrations were not pH-dependent. 2) In urines from patients, the pH was negatively associated with the concentration of some urinary parameters. However, concentrations of all the parameters were strongly and positively correlated with urinary creatinine, and relationships with pH were no longer evidenced after creatinine-normalization. CONCLUSIONS: The need for urine pH adjustment does not seem necessary when considering renal function. However, from an analytical and accreditation standpoint, the relationship between urine pH and several parameters justifies its measurement.

High frequency of a deletion polymorphism of the angiotensin-converting enzyme gene in asthma.

BACKGROUND: An insertion-deletion polymorphism of the angiotensin-converting enzyme (ACE) gene has been shown to be associated with levels of ACE. Because ACE is heavily expressed in the lungs and plays a key role in the metabolism of angiotensin II and bradykinin, which are potentially involved in the pathogenesis of asthma, we tested the hypothesis of an association between the polymorphism of the ACE gene and asthma. METHODS: Seventy-nine patients with asthma, 54 healthy subjects, and 33 patients with nonasthmatic lung disease were studied. Pulmonary function tests were performed in patients with asthma, and the ACE genotypes were determined in all subjects by the polymerase chain reaction. RESULTS: The ACE genotype distribution was similar in healthy subjects and in patients without asthma. By contrast, the population of patients with asthma was characterized by a higher prevalence of the DD genotype of ACE (odds ratio, 2.09; 95% confidence interval, 1.05 to 4.16; p = 0.023). No difference in pulmonary function test results was detected in asthmatic patients according to the distribution of ACE genotypes. CONCLUSION: This study reports an association between the DD genotype of ACE and asthma, which is not related to the degree of airway obstruction. These results need to be confirmed by a larger case-control study.