Urine pH

Increasing urine pH either promotes solubility of the poison, or in the case of weak acids (i.e., with a dissociation constant, pKa, slightly lower than the urinary physiologic pH), information technology increases the proportion of poison that is ionized, which enhances urinary elimination.

From: Handbook of Dialysis Therapy (Fifth Edition) , 2017

Laboratory Assessment of Kidney Affliction

In Pocket Companion to Brenner and Rector'southward The Kidney (Eighth Edition), 2011

Urine pH

Urine pH is commonly measured with a reagent test strip. Most commonly, the double indicators methyl red and bromthymol blue are used in the reagent strips to give a broad range of colors at unlike pH values. In conjunction with other specific urine and plasma measurements, urine pH is oftentimes invaluable in diagnosing systemic acid-base disorders. Past itself, however, urine pH provides little useful diagnostic information. The normal range for urine pH is iv.5 to vii.8. Very alkali metal urine (pH > 7.0) is suggestive of infection with a urea-splitting organism, such as Proteus mirabilis. Prolonged storage can pb to overgrowth of urea-splitting bacteria and a high urine pH. However, diet (vegetarian), diuretic therapy, vomiting, gastric suction, and alkali therapy tin can also cause a high urine pH. Low urine pH (pH < 5.0) is seen most unremarkably in metabolic acidosis. Acidic urine is also associated with the ingestion of large amounts of meat.

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Approach to the Patient with Renal Disease

Donald W. Landry , Hasan Bazari , in Goldman's Cecil Medicine (20 Fourth Edition), 2012

pH

Urine pH typically is 5 equally a result of daily internet acid excretion. An alkaline pH frequently is noted after meals, when an "alkaline tide" to balance gastric acrid excretion increases urine pH. A high urine pH also is seen in patients who are on a vegetarian diet. An exceptionally high urine pH is indicative of an infection with a urea-splitting organism, such as Proteus species (Affiliate 292). An inappropriately high urine pH in the setting of systemic not–anion gap metabolic acidosis may exist seen in certain forms of renal tubular acidosis (RTA; Chapter 130). In a proximal RTA, the urine pH is high until the tubular reabsorption threshold for bicarbonate, which is abnormally low, is reached. At this betoken, the urine pH decreases to five. In distal RTA, the disability to create a sufficient gradient for hydrogen ions results in a urine pH that is always college than 5.5; the urine cyberspace accuse gives complementary and confirmatory information. In type four RTA, the urine pH is oft 5, and the urine cyberspace charge is often positive, thereby confirming the absenteeism of significant amounts of ammonium in the urine; this defect is exacerbated past the accompanying hyperkalemia.

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Urinary Disorders

Jeanne A. Barsanti , in Small Animal Clinical Diagnosis by Laboratory Methods (Fifth Edition), 2012

Urine pH

Analysis

Urine pH is usually measured with a pH test pad on a urine reagent strip. However, results are not very accurate as compared to pH meters. 29,34 Portable pH meters should be used when accurate urine pH measurements are needed. Storage of urine in capped containers at room or refrigeration temperatures for at least 24 hours does non affect urine pH as measured with a pH meter. 1

Normal Values

Normal dogs and cats may have a urine pH of v.0 to viii.5.

Danger Values

None.

Artifacts

Urine pH may be falsely increased if the urine specimen container is allowed to stand open at room temperature, which leads to loss of CO 2; or by contagion by detergents or disinfectants.

Drug Therapy That May Alter Results

Decreased urine pH may be the consequence of urinary acidifiers such as methionine, mandelate, phosphate salts, or ammonium chloride. Increased urine pH may be caused by acetazolamide, bicarbonate, or potassium citrate.

Causes of Acid or Alkaline Urine

Any urine pH tin be normal. Urine pH is a crude index of acid-base balance and is not a reliable index of blood pH (east.one thousand., a vomiting patient with secondary hypochloremia may have aciduria despite systemic alkalosis, because it is conserving bicarbonate equally an anion). Causes of acid urine include ingestion of meat, respiratory and metabolic acidosis, severe vomiting with chloride depletion, severe diarrhea, starvation, pyrexia, and assistants of urinary acidifiers. Causes of alkaline urine include a contempo meal (i.east., postprandial alkali metal tide), ingestion of alkali (e.g., bicarbonate or citrate), UTI with urease-producing bacteria (typically Staphylococcus or Proteus spp.), renal tubular acidosis (RTA), diets rich in vegetables and cereals, and metabolic and respiratory alkalosis.

Persistently alkaline urine is an indication for complete urinalysis and urine civilisation. If no reason for alkaline urine is found on history, urinalysis, or urine culture, distal RTA may be considered, although information technology is rare. Both distal and proximal RTA cause hyperchloremic metabolic acidosis with a normal anion gap and oft produce hypokalemia (see Chapter 6).

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Feed Ingredients | Feed Supplements: Anionic Salts

G.R. Oetzel , in Encyclopedia of Dairy Sciences (2nd Edition), 2011

Monitoring the Response to Dietary Acidification

Monitoring urinary pH after feeding supplemental anions is a straight approach to establishing the optimal dose of anions inside a dairy herd. An reward of this approach (overrelying on calculated DCAD lonely) is that information technology accounts for inaccuracies in mineral analyses and for unexpected changes in forage mineral content. Mean urinary pH can exist evaluated by obtaining urine from a group of at least 8 animals near parturition. The animals chosen should have been on the anionic diet for at least 2 days prior to testing. When acidification is optimal, mean urinary pH for the group of cows tested will be nigh 7.0. Mean urinary pH values beneath about 6.0 indicate overacidification and advise that the dose of anions could be reduced. Impaired dry matter intake is the primary hazard associated with dietary overacidification. Conversely, urinary pH values higher up about 7.5 reverberate inadequate acidification and suggest that more anions are needed. Simply a small add-on of anions may exist necessary to reduce urinary pH to the optimal range, because urinary pH decreases rapidly as DCAD decreases from most 50   meq   kg-1.

Because in that location may be pregnant variations in urinary pH related to time afterward feeding, nigh accurate results will be obtained by collecting urine samples at a standard time, preferably within a few hours of feeding. Urinary pH may be measured on-subcontract past dairy producers or veterinarians using pH paper, urine dipsticks, or a calibrated pH meter.

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Neglected Factors in Pharmacology and Neuroscience Enquiry

In Techniques in the Behavioral and Neural Sciences, 1994

Urinary Drug Excretion

Urinary pH is reported by some authors to be afflicted past fasting. Koike et al. (1984) measured in fed rats a gradual decrease of the pH-value from 7.2 to 5.8 during the day, whereas in fasted rats this variation during the day was significantly less, viz. from half dozen.2 to v.eight (fig. 13.ten).

Fig. 13.10. Diurnal Variation of Urinary pH in Fed and in 24 h Fasted Rats (Mean Values ± s.e.).

 (adapted from Koike, Thou., et al.: J. Pharm. Sci. 73, 1697–1700, 1984

The urinary excretion of weak acids and bases is markedly dependent on the urinary pH. For this reason information technology may exist expected that the pharmacokinetics of such drugs in fed and fasted animals may be modulated differently during the day.

Koike et al. (1984) determined the plasma concentrations of cinoxacin after i.five. assistants to the rat at 12.00 h and xv.00 h, respectively (fig. thirteen.11). Cinoxacin, an antibacterial agent, is a weak acrid (pKa: four.threescore), which is excreted almost completely unchanged in rat urine. When injected at 12.00 h the decrease of the plasma concentration of the drug is lower in the fasted rat than in the fed animal. The more than acid urinary pH in fasted rats favours renal reabsorption. When injected at 15.00 h the grade of the plasma concentrations is comparable in fed and fasted animals in accordance with the minor differences in urinary pH at this time of the day.

Fig. 13.11. Time Courses of Plasma Cinoxacin Levels in Fed and in 24 h Fasted Male person Rats Later an i.v. Dose of 20 mg/kg at 12.00 and at 15.00 h.

 (adjusted from Koike, One thousand., et al.: J. Pharm. Sci. 73. 1697–1700, 1984)

The difference in urinary excretion during the first hours of the light cycle will besides contribute highly to the larger AUC in the fasted rat in comparing to the AUC of the fed creature when cinoxacin is orally administered at 11.00 h (fig. thirteen.12).

Fig. xiii.12. Plasma Cinoxacin Levels in Fed and in 24 h Fasted Male Rats Afterwards an Oral Dose of xx mg/kg at 11.00 h (mean values ± due south.due east.).

 (adapted from Koike, Thousand., et al.: J. Pharm. Sci. 73, 1697–1700, 1984)

Mention of the diurnal variation of the urinary pH in fed and fasted animals could exist traced in just a few publications. Laliberte et al. (1977) state that: "The pH of the urine samples of both control and fasted rats remained at 7 for the unabridged period of urine collection". The aforementioned laboratory reports a urinary pH of seven.5 in fasted and vii.0 in control rats, without clear indication of the exact time.

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Extracorporeal Treatment of Poisonings

Stuart Abramson M.D., G.P.H , in Chronic Kidney Disease, Dialysis, and Transplantation (Tertiary Edition), 2010

Urinary pH Manipulation

Urinary pH manipulation can effectively decrease tubular reabsorption of weak nonpolar acids and bases. Manipulation of the urine pH can enhance the excretion of acidic or basic chemicals through a machinery known as ion trapping. 23 The membranes of the nephron are generally more permeable to nonionized and nonpolar molecules. Compounds are filtered and secreted in the nonionized form of weak acids or bases past nonionic diffusion across cell membranes. With manipulation of urinary pH, the change in the intraluminal pH promotes the formation of a higher intratubular fraction of the ionized drug, finer trapping the ionized moiety in the urinary infinite since the ionized class tin no longer cross the cell membrane. 23 For weak acids, alkaline urine increases the fraction that is ionized. Acidic urine does the same for weak bases. In each case, an increase in the ionized course of the drug decreases reabsorption, enhancing renal elimination. 24 Urine alkalinization can be used to enhance the elimination of salicylates and phenobarbital. 25 At that place is as well some testify for its efficacy in methotrexate toxicity and poisoning with the chlorophenoxy herbicides. 23 Urinary acidification can be used to enhance the elimination of chloroquine, amphetamine, quinine, and phencyclidine. 26

Alkalinization of the urine can be achieved by adding 150 mEq sodium bicarbonate to 1 L of dextrose 5% in water (D5W) to run at 100 to 250 cc/hr. The goal is to accomplish a urinary pH of greater than vii, which usually requires 0.25 to 0.5 mEq/kg/hr (Tabular array 51-ane). 27 This tin only be accomplished if the patient has intact renal function, and urinary alkalinization should be avoided in patients with severe acute kidney injury (AKI). Risks of urinary alkalinization include volume overload, alkalemia, hypernatremia, and hypokalemia. 23 It is important to treat the hypokalemia, because it will preclude the alkalinization of the urine past promoting distal hydrogen secretion in identify of potassium secretion. Hypokalemia tin can exist avoided by adding 20 to 40 mEq potassium chloride to each liter of D5W with sodium bicarbonate. 19 Acetazolamide will enhance urinary alkalinization but should exist avoided because of the risk of worsening systemic acidemia, which tin raise toxicity of sure poisonings, most notably salicylates. 28

Urinary acidification is rarely used because of the potential to worsen renal injury in many poisonings. Arginine hydrochloride or ammonium chloride have been shown to be effective urinary acidification agents. Although urinary acidification may enhance emptying of weak bases, it cannot be recommended every bit a treatment for toxicity from these compounds. Complications of urinary acidification include myoglobinuria, acute renal failure, and hyperkalemia. 26

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Nephrolithiasis and Nephrocalcinosis

Rebeca D. Monk , David A. Bushinsky , in Comprehensive Clinical Nephrology (Fourth Edition), 2010

Laboratory Findings

Urine pH is generally high in patients with struvite and calcium phosphate stones but low in patients with uric acid and calcium oxalate stones. The specific gravity, if it is high, will confirm inadequate fluid intake in many patients. Hematuria may imply active stone illness with crystal or stone passage. Examination of the urine may reveal red blood cells along with feature crystals ( Fig. 57.eight). Bacteriuria with urine pH above half-dozen to six.five suggests struvite stones. Urine should exist cultured, and because many leaner produce urease fifty-fifty when urine bacterial colony counts are depression, the microbiology laboratory should be instructed to type the organism even if there are fewer than 100,000 colony-forming units/ml.

Claret tests required in the basic evaluation are serum electrolytes (sodium, potassium, chloride, and bicarbonate), creatinine, calcium, phosphorus, and uric acid. If the serum calcium concentration is elevated or at the upper limit of normal, particularly if the serum phosphorus concentration is low, a serum parathyroid hormone level should exist measured. A low potassium or bicarbonate level may bespeak a cause of hypocitraturia, such equally distal renal tubular acidosis.

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Electrolytes: Acid–Base Residue

P.B. Marker , ... A.Chiliad. Jardine , in Encyclopedia of Human being Nutrition (Third Edition), 2013

Measurement of Urinary Acid Excretion

Urinary pH can exist measured by commercially available 'dipsticks' or by using a pH meter on a fresh sample of urine. Loss of COii or the production of NH 4 + from urea-splitting organisms in infected urine will modify the pH with fourth dimension. The excretion of stock-still acid tin can exist determined by chemical titration of urine to pH 7.4, and is commonly termed 'titratable' acidity. The amount of NH four + is normally estimated from the departure between the most abundant cation (Na+, G+) and anion (Cl−) concentrations in the urine.

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Drug toxicity and overdose

Derek M. Waller BSc (HONS), DM, MBBS (HONS), FRCP , Anthony P. Sampson MA, PhD, FHEA, FBPhS , in Medical Pharmacology and Therapeutics (Fifth Edition), 2018

Renal elimination

Altering urine pH, while maintaining normal urine flow, can exist effective in increasing the renal emptying of drugs that are weak electrolytes. Modification of urine pH to increase the extent of ionisation of the drug will reduce reabsorption from the renal tubule (run across Chapter 2). Weak acids, such equally salicylates, are excreted more readily when urine is alkalinised (alkaline diuresis, accomplished past giving sodium bicarbonate).

Forced diuresis with intravenous infusion of large quantities of fluid was advocated in the past for drugs or toxic metabolites that are mostly eliminated unchanged by the kidney. However, serious disturbances of fluid or electrolyte residual can occur, and therefore information technology is no longer recommended.

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Nephrology

Sharma S. Prabhakar G.D., M.B.A., F.A.C.P., F.A.S.Due north. , in Medical Secrets (Fifth Edition), 2012

96 Summarize the weather condition that favor the formation of each kind of stone.

In general, an alkaline urine pH favors precipitation of inorganic stone such as calcium phosphate that undergoes rearrangement into hydroxyapatite. Alkali metal urine pH and high concentrations of urinary ammonia pb to supersaturation of magnesium ammonium phosphate (struvite). This environment is created by the presence of urea-splitting bacteria (commonly Proteus, Pseudomonas, Klebsiella, and Staphylococcus), which contain the enzyme urease and convert urea to ammonia and COii. An acid pH favors atmospheric precipitation of organic stone such as uric acrid and cystine. Urine pH has little effect on calcium oxalate solubility and, therefore, piddling influence on formation of these stones.

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