Development of a reference interval for urinary ammonia-to-creatinine ratio in feline patients.

BACKGROUND: Disruption of acid-base homeostasis can lead to many clinical problems. Ammonia excretion by the kidneys is critical to maintaining acid-base homeostasis through bicarbonate production. Measurement of ammonia excretion may help determine if the kidneys are properly functioning in maintaining acid-base balance. Reference intervals are essential tools for clinical decision-making but do not currently exist for urinary ammonia-to-creatinine ratio (UACR) in feline patients. OBJECTIVE: This study aimed to generate a reference interval (RI) for UACR in healthy adult cats. METHODS: The study used samples from client-owned adult healthy cats that presented to the University of Florida Primary Care and Dentistry service (n = 92). Physical examination, serum biochemistry, urinalysis, urine ammonia, and creatinine concentrations were measured. Cats were excluded if there were significant abnormalities in their urinalysis or biochemistry panel. The RI for UACR was calculated according to the recommendation of the American Society for Veterinary Clinical Pathology. The UACR was evaluated for correlation with serum bicarbonate, weight, age, and sex. RESULTS: The RI for UACR was 3.4-20.7 with 90% confidence intervals for the lower and upper limits of (3.0-3.7) and (16.0-23.7), respectively. No significant correlation with age, sex, or weight was found. There was no discernable relationship between serum bicarbonate and UACR. CONCLUSIONS: Establishing an RI for UACR in healthy adult cats will allow further studies to determine if changes in UACR are observed during specific disease states.

Racial differences in T-lymphocyte response to glucocorticoids.

BACKGROUND: Asthma morbidity and mortality is increased in blacks. OBJECTIVE: The primary objective of this cross-sectional study was to determine if blacks, asthmatic or nonasthmatic, displayed diminished T-lymphocyte response to glucocorticoids in vitro compared to their white counterparts. If differences were noted, this would suggest a racial predisposition to decreased glucocorticoid responsiveness among blacks. METHODS: Asthmatic (n = 395, 27% blacks) and control (n = 202, 52% blacks) subjects recruited from National Jewish Medical and Research Center and from the surrounding community participated in the study. In vitro glucocorticoid responsiveness was determined by assessing the log-transformed concentration of dexamethasone required to suppress phytohemagglutinin-induced T-lymphocyte proliferation by 50% (log(10) IC(50)). Asthma medication history, atopic status, and spirometric lung function measures corrected for race were collected. RESULTS: Black and white asthmatic subjects had similar FEV(1) percentage of predicted values and inhaled and oral glucocorticoid requirements. Black asthmatic subjects displayed significantly diminished glucocorticoid responsiveness compared to white asthmatic subjects, as follows: median (first, third quartile) log(10) IC(50) values of 1.00 nmol (0.48, 1.83) vs 0.78 nmol (0.29, 1.45) [p = 0.028]. Similar results were found between black and white control subjects, as follows: median, 1.26 nmol (0.70, 2.14) vs 0.95 nmol (0.55, 1.48) [p = 0.01]. Age, race, and basal T-lymphocyte activity were significantly positively correlated to the log(10) IC(50) values. CONCLUSION: Our observation that black asthmatic subjects and non-asthmatic control subjects require greater concentrations of glucocorticoid in vitro to suppress T-lymphocyte activation suggests that blacks have a racial predisposition to diminished glucocorticoid responsiveness, which may contribute to their heightened asthma morbidity.