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Urine pH: the Effects of Time and Temperature after Collection

DOI:10.1093/jat/31.8.486
Authors:
Janine D Cook
Janine D Cook
Janine D Cook
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Kathy A Strauss at University of Maryland, Baltimore
Kathy A Strauss
Yale H Caplan at University of Maryland, Baltimore
Yale H Caplan
Charles Lodico at U.S. Department of Health and Human Services
Charles Lodico
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The Mandatory Guidelines for Federal Workplace Drug Testing Programs provide criteria for specimen validity testing, including urine pH cut-offs, to report a urine specimen as adulterated or invalid. Since the urine pH criteria for invalid classifications, ≥ 3 and < 4.5 or ≥ 9 and < 11, became effective in November 2004, a number of specimens with results within the upper invalid limits, typically in the range of 9.1 to 9.3, have been reported with no evidence of adulteration. This study evaluated the hypothesis that these pH findings were the result of exposure to increased environmental temperatures during specimen standing and transport. Indeed, increased storage temperatures were associated with increased urine pH, with the magnitude of the change related to both storage time and temperature. The pH values of specimens stored at −20°C are relatively stable, whereas pH results > 9 are achieved at storage temperatures of room temperature or higher. It is noteworthy that no condition(s) produced a specimen with a pH > 9.5. Degradation of nitrogenous urine analytes is most likely responsible for the noted increases in pH. These findings are intended to supplement information used by the Medical Review Officers who are responsible for interpreting such marginally invalid pH results.
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... Although laboratory pH meters seem to be the gold standard method to urinary pH monitorization, it is not feasible for patients to use it at home. Moreover, it has been already published by Cook et al. [18] that the time between patient's urine collection and its analysis in the laboratory can alter the pH values. Therefore, seems like a portable pH meter could solve this issue, since it gives immediate result after patient's collection. ...
Role, Cost, and Availably of Urinary pH Monitoring for Kidney Stone Disease—A Systematic Review of the Literature
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... pH also changes in pathological conditions. An increase in the hydrogen index above 7 is observed in metabolic and respiratory alkalosis [6], in chronic renal failure [7], hyperfunction of the parathyroid gland [8], with the administration of certain medications [9], in the case of neoplasms of the urinary system, and in urinary tract infections associated with microorganisms that break Microorganisms 2023, 11, 862 2 of 10 down urea [10]. A decrease in pH below 4 is associated with metabolic and respiratory acidosis [6], diabetes mellitus, obesity [11], and with taking some medications [12]. ...
Effect of pH, Norepinephrine and Glucose on Metabolic and Biofilm Activity of Uropathogenic Microorganisms
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  • Mar 2023
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... However, the precipitates yielded in R 2 and R 3 were no significant difference. Since the R 3 reactor is temperaturecontrolled in an airtight environment, bacterial growth is mostly inhibited, urea hydrolysis happens gradually; as a result, phosphate and calcium did not precipitate much and remain in the solution [29]. Spontaneous formation of struvite is reported to be dependent on the pH of the solution, the solution supersaturation, and on the presence of impurities [30]. ...
Effects of storage conditions, pH and Mg:P ratio on the precipitation process for phosphate recovery
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  • Feb 2022
Phosphorus (P) is an essential yet non-renewable nutrient, so recovering it from urine is getting more attention since it has a high concentration of nutrients. This study aimed to investigate the impacts of temperature, storage condition on urine's characteristics, and the effects of pH, Mg:P ratio, and calcium (Ca) ion on yielded magnesium phosphate hydrate (Mg3(PO4)2•xH2O) crystallization from fresh urine. The results indicated that the urine stored at 4 °C in a sealed environment created less spontaneous precipitation. The findings showed that the favorable condition for Mg3(PO4)2•xH2O recovery was at pH 10.5 and Mg:P of 1.3. The XRD analysis confirmed that P was crystallized as Mg3(PO4)2•xH2O phase with an average particle size of 0.5 mm. Furthermore, SEM-EDS images suggested the Ca and K might co-precipitate with Mg3(PO4)2•xH2O. These findings indicate that the potential of P recovery from nutrient-rich wastewater can both reduce environmental pollution and profit from phosphate fertilizers.
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... However, the precipitates yielded in R 2 and R 3 were no significant difference. Since the R 3 reactor is temperaturecontrolled in an airtight environment, bacterial growth is mostly inhibited, urea hydrolysis happens gradually; as a result, phosphate and calcium did not precipitate much and remain in the solution [29]. Spontaneous formation of struvite is reported to be dependent on the pH of the solution, the solution supersaturation, and on the presence of impurities [30]. ...
Effects of storage conditions, pH and Mg:P ratio on the precipitation process for phosphate recovery
Article
  • Feb 2022
Phosphorus (P) is an essential yet non-renewable nutrient, so recovering it from urine is getting more attention since it has a high concentration of nutrients. This study aimed to investigate the impacts of temperature, storage condition on urine's characteristics, and the effects of pH, Mg:P ratio, and calcium (Ca) ion on yielded magnesium phosphate hydrate (Mg3(PO4)2•xH2O) crystallization from fresh urine. The results indicated that the urine stored at 4 °C in a sealed environment created less spontaneous precipitation. The findings showed that the favorable condition for Mg3(PO4)2•xH2O recovery was at pH 10.5 and Mg:P of 1.3. The XRD analysis confirmed that P was crystallized as Mg3(PO4)2•xH2O phase with an average particle size of 0.5 mm. Furthermore, SEM-EDS images suggested the Ca and K might co-precipitate with Mg3(PO4)2•xH2O. These findings indicate that the potential of P recovery from nutrient-rich wastewater can both reduce environmental pollution and profit from phosphate fertilizers.
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Evaluation of human urine purification using rice husk charcoal as the adsorbent
Article
Full-text available
  • Jun 2023
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The surface and internal features of pubic hair: A comparative study with those of scalp hair
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Although pubic hair has been a subject of public interest, little is known about its structure or characteristics beyond its curly and coarse appearance. In this study, we investigated the surface and internal features of pubic hair from Korean males and compared them to those of scalp hair from the same donors. Our findings indicate that the cuticle layer of pubic hair has a greater number of scales than that of scalp hair, resulting in a thicker cuticle layer overall. Fourier-transform infrared (FT-IR) spectroscopy analysis showed that the protein in the cortex layer of pubic hair was less affected by exposure to urine or ammonia than the protein in the cortex layer of scalp hair. This suggests that the cuticle layer of pubic hair, which is thicker and composed of more scales, acts as a physical barrier that protects the hair's internal structure. Furthermore, we observed that the secondary and tertiary structures of keratin in the pubic hair cuticle layer are essentially different from those in scalp hair. Based on these findings, we hypothesize that the thickened cuticle layer in pubic hair may have evolved as a defence mechanism against chemical damage from urine, urea and ammonia.
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Empagliflozin and Renal Sodium-Hydrogen Exchange in Healthy Subjects
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Context: Sodium glucose co-transporter-2 inhibitors (SGLT2i) exert clinically relevant cardiorenal protection. Among several mechanisms, inhibition of the sodium-hydrogen exchanger-3 (NHE3) in proximal renal tubules has been proposed in rodents. Demonstration of this mechanism with the associated electrolyte and metabolic changes in humans is lacking. Objective: The present proof-of-concept study was designed to explore the involvement of NHE3 in modulating the response to SGLT2i in humans. Methods: Twenty healthy male volunteers received two tablets of empagliflozin 25 mg during a standardized hydration scheme; freshly voided urines and blood samples were collected at timed intervals for 8 hours. Protein expression of relevant transporters was examined in exfoliated tubular cells. Results: Urine pH increased after empagliflozin (from 5.81 ± 0.5 to 6.16 ± 0.6 at 6 hours, p = 0.008) as did urinary output (from 1.7 [0.6; 2.5] to 2.5 [1.7; 3.5] mL.min-1, p = 0.008) and glucose (from 0.03 [0.02; 0.04] to 34.8 [31.6; 40.2] %, p < 0.0001) and sodium fractional excretion rates (from 0.48 [0.34; 0.65] to 0.71 [0.55; 0.85] %, p = 0.0001), while plasma glucose and insulin concentrations decreased and plasma and urinary ketones increased. Non-significant changes in NHE3, pNHE3 and MAP17 protein expression were detected in urinary exfoliated tubular cells. In a time-control study in 6 participants, neither urine pH nor plasma and urinary parameters changed. Conclusions: In healthy young volunteers, empagliflozin acutely increases urinary pH while inducing a substrate shift towards lipid utilization and ketogenesis, without significant changes in renal NHE3 protein expression.
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Production of microalgae on source-separated human urine
Chapter
  • Jan 2022
Approximately 80% of nitrogen, 50% of phosphorous, and 90% of potassium in domestic wastewater originate from human urine, depending on diet and lifestyle, use of detergents, etc. However, the production volume of urine is only 1–1.5 L per person per day, while the total wastewater discharge may be up to 150–250 L/d. In addition to large amount of N, P, and K, human urine also contains trace elements like B, Cu, Zn, Mo, Fe, Co, and Mn. Nitrogen and phosphorus are only partially captured in a reusable form in conventional centralized wastewater treatment systems. The development of urine-sorting toilets has made it possible to separate urine for nutrient recovery instead of directing the urine to centralized wastewater treatment plants. Microalgae, if grown on urine, may provide an economically and environmentally sustainable way to capture nutrients from urine as nutrients are utilized by the growing microalgal cells. This chapter reviews literature on the use of microalgae for nutrient recovery from source-separated urine. Scale of production, start-up, maintenance of the system, and all other aspects of a pilot reactor are discussed critically in this review.
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Stabilization and concentration of nitrogen in synthetic urine with peracetic acid and progressive freeze concentration
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  • Apr 2022
Peracetic acid (PAA) was used as an inhibitor to prevent urea hydrolysis in the recovery and concentration of nitrogen in a synthetic urine. Twenty mg/L of PAA was found to be effective in inhibiting urea hydrolysis for seven days before it was concentrated by the progressive freeze concentration (PFC) process. Ammonia concentration, total nitrogen (TN), pH, and electrical conductivity (EC) were monitored. The PFC process, operating with a coolant temperature of -12 °C and a stabilized synthetic urine temperature of 23 °C, reduced the volume of the stabilized synthetic urine by approximately 80% (concentration factor of 5.1) and concentrated the TN approximately 21,000 mg/L with ammonia concentration of approximately 50 mg/L-N. Seven days after the PFC treatment, the urea in the concentrated synthetic urine continued to be fairly stable although addition of PAA may be needed to stabilize the concentrated solution further. The experimental results showed that a combination of using PAA as an oxidizing agent and the PFC process can be an effective and suitable process for source separation systems to concentrate urine to recover nitrogen and produce liquid fertilizer.
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Effects of reducing dietary cation-anion difference on lactation performance and nutrient digestibility of lactating cows and ammonia emissions from manure
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Outpatient Urine Culture
Article
Full-text available
Background Dysuria is one of the most common presenting complaints of young women, and urinalysis is one of the most common laboratory tests performed. Despite the fact that the midstream clean-catch technique is commonly used for urine collection, contaminated urine cultures occur with distressing regularity. The midstream clean-catch technique is time-consuming to explain, frequently not performed correctly by patients, costly for supplies, often embarrassing for patients and staff, and of unproven benefit. Therefore, we designed a study to compare various methods of obtaining specimens for culture from acutely dysuric young women.Methods A total of 242 consecutive female patients who presented with symptoms suggestive of a urinary tract infection were randomized into 3 groups. The first group (n = 77) was instructed to urinate into a clean container. No cleansing was done, and the specimen was not obtained midstream. The second group (n = 84) was instructed to collect a midstream urine sample with perineal cleansing and spreading of the labia. In an attempt to decrease contamination from the vagina, the third group (n = 81) was given the same instructions as group 2, with the addition of using a vaginal tampon. Contamination rates were calculated for all 3 groups.Results Contamination rates for the 3 groups were nearly identical (29%, 32%, and 31%, respectively). Comparing the no-cleansing group with the combined cleansing, midstream groups also showed no difference in contamination rates (28.6% and 31.5%, respectively, with P = .65).Conclusions In young, outpatient women with symptoms suggestive of a urinary tract infection, the midstream clean-catch technique does not decrease contamination rates.
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Effectiveness of an outpatient urine screening program
Article
Full-text available
  • Jan 1978
We evaluated the effectiveness of a routine outpatient urinalysis screening program on a sample population of 2600 patients. The 189 abnormal urine results found in 182 patients were followed up by study of any new clinical and laboratory investigations or therapeutic modifications initiated on the basis of any abnormal test result. The urinalysis screening program appeared to have significant bearing on diagnosis or treatment in only 13 patients. Abnormalities found in 150 of the 182 patients were either not noted or no further positive action was taken. Thus we concluded that under the conditions of this study the urine screening program added to hospital costs without significant benefit to the patient.
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Investigation of the stability of drugs of abuse in urine sample by capillary zone electrophoresis
Article
  • Aug 1997
The stability of amphetamine and morphine in spiked or forensic urine samples after long-term storage was investigated using capillary zone electrophoresis (CZE). Both analytes were quantitatively determined in fresh or stored urine (for 3 to 10 months) in four kinds of containers (glass tube with rubber cap, glass tube with screw cap, PP plastic and PE plastic tube) at 4°C, -20°C, room temperature (RT) (25-27°C) or high temperature (HT) (35°C). Slight decrease of drug recovery was observed in samples stored at low temperatures (4 or -20°C) after 10 months, while those stored at higher temperatures (RT or HT) degraded dramatically. Both analytes totally disappeared in CZE electropherograms of forensic urine samples stored at HT for 10 months, The type of container used had little effect on the stability of the drugs. The results suggest: 1) all confirmed drug-positive urine samples should be stored frozen to maintain drug stability, and 2) CZE is a simple and convenient method for testing drug stability in urine.
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Determination of morphine and 6-acetylmorphine in plasma by high-performance liquid chromatography with fluorescence detection
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Screening for drugs of abuse: Effect of heat-treating urine for safe handling of samples
Article
  • Jul 1990
Heating urine samples from high-risk patients for 1 h at 56 degrees C is no longer believed to completely inactivate human immunodeficiency virus (HIV; AIDS virus). To protect staff who are handling infectious samples such as those from drug-addiction units, heating at a higher temperature may be necessary. We report the stability to heat treatment (at 60, 70, and 100 degrees C) at pH 5.1 and 7.6 of some commonly abused drugs, namely, methadone, pethidine, amphetamine, the cocaine metabolite, benzoylecgonine, and the dextropropoxyphene metabolite nordextropropoxyphene. Heat-treating urine at 60 degrees C for 1.5 h or 70 degrees C for 1 h did not significantly affect the measured concentrations of these drugs. However, heat treatment at 100 degrees C for 1 h reduced the recovery of all the drugs. Benzoylecgonine and amphetamine were most susceptible to the different forms of heat treatment.
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