Urinary pH (urinary + ph)

Distribution by Scientific Domains

Selected Abstracts

Non-patient related variables affecting levels of vascular endothelial growth factor in urine biospecimens

M. J. Kirk
Abstract Vascular endothelial growth factor (VEGF) is an angiogenic protein proposed to be an important biomarker for the prediction of tumour growth and disease progression. Recent studies suggest that VEGF measurements in biospecimens, including urine, may have predictive value across a range of cancers. However, the reproducibility and reliability of urinary VEGF measurements have not been determined. We collected urine samples from patients receiving radiation treatment for glioblastoma multiforme (GBM) and examined the effects of five variables on measured VEGF levels using an ELISA assay. To quantify the factors affecting the precision of the assay, two variables were examined: the variation between ELISA kits with different lot numbers and the variation between different technicians. Three variables were tested for their effects on measured VEGF concentration: the time the specimen spent at room temperature prior to assay, the addition of protease inhibitors prior to specimen storage and the alteration of urinary pH. This study found that VEGF levels were consistent across three different ELISA kit lot numbers. However, significant variation was observed between results obtained by different technicians. VEGF concentrations were dependent on time at room temperature before measurement, with higher values observed 3,7 hrs after removal from the freezer. No significant difference was observed in VEGF levels with the addition of protease inhibitors, and alteration of urinary pH did not significantly affect VEGF measurements. In conclusion, this determination of the conditions necessary to reliably measure urinary VEGF levels will be useful for future studies related to protein biomarkers and disease progression. [source]

Variation in the incidence of and risk factors for the development of nephrolithiasis after radical or partial nephrectomy

Aditya Bagrodia
Study Type , Prevalence (retrospective cohort) Level of Evidence 2b OBJECTIVE To examine incidence of and risk factors for the development of nephrolithiasis in patients treated with radical nephrectomy (RN) or partial nephrectomy (nephron-sparing surgery, NSS). PATIENTS AND METHODS The study comprised a single-centre review of 749 patients treated with RN or NSS from August 1987 to June 2006. Demographics, medical and stone history, metabolic variables and postoperative stone events were recorded. Data were analysed within subgroups based on treatment (RN vs NSS). Multivariate analysis was used to identify risk factors for postoperative stone formation. RESULTS In all, 499 patients had RN and 250 had NSS (mean age 57.9 years; mean follow-up 6.3 years). There were no significant differences in their demographic factors, but tumours were significantly larger in RN (P < 0.001). There was no significant difference in preoperative urinary pH < 6.0 or stone history. Significantly fewer patients after NSS than RN formed calculi (NSS 1.6% vs RN 8.4%, P < 0.001), developed hypobicarbonataemia (NSS 7.2% vs RN 12.8%, P= 0.020), and a urinary pH of <6.0 (NSS 11.2% vs RN 19.4%, P= 0.004). Multivariate analysis showed that RN (odds ratio 18.18), postoperative urinary pH < 6 (15.63), previous stone disease (13.7), age <60 years (7.33, all P < 0.001), body mass index ,30 kg/m2 (3.26, P= 0.033), male gender (2.67, P= 0.039), and hypobicarbonataemia (2.46, P= 0.034) were significantly associated with the development of postoperative calculi. CONCLUSIONS Patients undergoing RN have a significantly higher incidence of postoperative nephrolithiasis than a well-matched cohort undergoing NSS. In addition to RN, male sex, urinary pH < 6.0, hypobicarbonataemia, history of stone disease, obesity, and age <60 years were significantly associated with postoperative stone formation. [source]

Effect of Intravenous Albumin Infusion on Brain Salicylate Concentration

Steven C. Curry MD
Background:Salicylate poisoning appears to result in death, despite supportive care, once a critical brain salicylate concentration is reached. The binding of salicylate to albumin is saturable; free plasma salicylate concentrations rise disproportionately to total drug levels. Because unbound salicylate distributes into the brain, the authors questioned whether an intravenous (IV) infusion of albumin would cause a redistribution of salicylate from the brain back into the plasma, which might allow enough time for hemodialysis to be instituted. Objectives:To determine if IV albumin infusion would lower brain salicylate concentrations through redistribution in a porcine model of acute salicylate poisoning. Methods:In a randomized controlled trial, 17 swine under anesthesia and controlled ventilation received 400 mg/kg of sodium salicylate IV over 15 minutes. At 60 minutes, nine animals received 1.25 g/kg albumin (25% solution) IV over 15 minutes, while eight control animals received an equal volume of normal saline (5 mL/kg). Arterial pH was maintained between 7.45 and 7.55. Serial measurements of serum albumin as well as free and total salicylate concentrations were obtained, and urine was collected for measurement of total salicylate excretion. At 180 minutes, animals were killed and brains harvested for measurement of brain salicylate concentrations. Results:Average peak serum total salicylate concentrations of 105.5 and 109 mg/dL were achieved in control and albumin-treated animals, respectively. Albumin infusion was accompanied by statistically significant increases in serum total salicylate concentrations (median from 79.5 to 86.9 mg/dL at 75 minutes), while levels decreased slightly in control animals. Serum free salicylate concentrations decreased slightly in albumin-treated animals, but the difference was not statistically significant. Median brain salicylate concentrations were about 14% lower in the albumin treatment group (17.8 mg/100 g brain) compared with controls (20.5 mg/100 g brain); this approached statistical significance (p = 0.075). Median urinary salicylate excretion was higher in the albumin-treated group (0.83 vs. 0.48 g; p = 0.072), with similar urinary pH and volumes in both groups. Conclusions:In this animal model of salicylate poisoning, IV infusion of 1.25 g/kg albumin was accompanied by a 14% decline in median brain salicylate concentrations, which approached statistical significance. [source]