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Urine pH Testing: High & Low Levels + How to Fix

Written by Will Hunter, BA (Psychology) | Reviewed by Selfhacked Science Team | Last updated:

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Urine pH can tell you a lot about how your diet is affecting the pH in your body and how well your kidneys are working. Although diet is the major factor that determines urine pH, certain drugs and diseases can also have an effect. Urine pH is important when it comes to monitoring your risk of kidney stones, as extreme pH levels cause stones to form. Read on to see what urine pH can reveal about your health and what you can do to reduce or increase your level.

What is Urine pH?

pH is a measure of how acidic or alkaline (basic) a water-based fluid is. Every fluid in the body has a unique pH range that is optimal for health. For example, blood pH is usually maintained in a tight range between 7.35 and 7.45. Even a slight increase or decrease in blood pH can be dangerous. Saliva normally has a pH range of 6.2-7.6, which prevents bad bacteria from growing and neutralizes acids in foods. The pH inside of cells is 7.2 [1, 2, 3].

Urine also has a unique pH range. The kidneys help keep the blood pH from going too low by filtering acids from the blood and releasing them in the urine. It also helps prevent blood pH from going too high by releasing alkaline compounds (bicarbonate) into the urine. This means that changes in blood pH cause similar changes in the urine pH [4, 5].

Diet, certain drugs, infections, and poor kidney function can all affect the urine pH. Diets high in protein from meat, fish, dairy, and grains can decrease urine pH (more acidic), whereas diets high in fruits and vegetables can increase urine pH (more alkaline) [6, 7, 8].

Urine pH Testing

Urine pH is tested as part of a routine urinalysis. It is often used to assess the risk of kidney stones, diagnose urinary tract infections (UTIs), or determine the effectiveness of antibiotics and other drugs that are affected by urine pH [9, 10, 11].

Dipstick vs. Electrode

Urine pH can be measured using a dipstick, which is a test strip that is placed in a urine sample and reveals the pH depending on how the color of the strip changes.

The advantages of dipstick measurements include convenience, cost, and the ability to test pH at home. However, it is not as accurate as an electrode measurement and may cause either a lack of treatment or unnecessary medication in some patients [12, 13].

The gold standard of measuring urine pH is a pH meter that uses an electrode. It is much more accurate, however, it is more expensive [12].

Fasting vs. Spot vs. 24-Hour Test

For a routine urinalysis, a urine sample is provided after an overnight fast. This is referred to as a fasting urine sample. Samples were taken in the morning generally result in more alkaline urine [14].

A spot urine sample is a random sample taken during the day.

Urine pH is known to change throughout the day, peaking in the middle of the day, and decreasing after each meal. To get an accurate measurement of the average urine pH throughout the day, 24-hour urine tests are used. A 24-hour urine test involves collecting all urine for a single day in a container that is later measured in a lab [15].

Fasting and single-spot samples are not accurate enough to assess and treat people with kidney stones [16, 14].

Normal Urine pH levels

The normal range for urine pH is between 4.5 and 8. A neutral pH is 7 with any number below that considered acidic. A urine pH above 7 is alkaline. Urine pH is slightly more alkaline in the morning than in the night. Women also tend to have slightly higher urine pH levels than men [14, 17, 18].

Improper storage conditions (high temperatures) before analysis can result in urine pH levels above 9, so if you see levels near this you may want to retest to be sure [19].

Causes of Low Urine pH Levels

1) Diet

Food is one of the most important factors in determining the pH of urine. Meat, fish, dairy, and grains all increase the number of acids that the kidney has to filter into the urine. Most vegetables and fruits (especially citrus) generate alkaline compounds, reducing the number of acids the kidneys must filter [20].

High fruit and vegetable intake and lower consumption of meat were linked to a more alkaline urine pH in 22k people [8].

In a study of 18 people, those who ate a diet high in protein and meat saw their urine pH decrease to 5.9 after three days. People who ate a diet high in vegetables and fruits and low in meats had their pH increase to 6.7 [21].

In a similar study of 26 people, those who ate a diet high in protein and meat saw their urine pH decrease to 5.9 after three days. People who ate a diet high in vegetables and fruits and low in meats saw their pH increase to 6.5 [22].

Protein increases the amount of acid produced in the body. The kidneys have to filter these acids into the urine, decreasing its pH. Multiple studies of 89 total people revealed that high protein diets make the urine more acidic [23, 24, 25].

2) Diarrhea

Urine pH was reduced from 6.7 to 5.5 in 24 people who experienced diarrhea. Diarrhea causes the loss of electrolytes, reducing blood pH (i.e. more acidic). The kidneys then compensate for this by releasing more acids in the urine [26].

3) High Blood Sugar and Diabetes

High blood sugar causes insulin resistance. This causes the kidneys to produce less ammonia, a compound that increases the pH of the urine [27].

In a study of 5k people, low urine pH was associated with higher blood sugar levels. Another study of 1k people found that those with urine pH below 5.5 had the highest degree of insulin resistance [28, 29].

A five-year observational study of 3.1k people showed that those with a urine pH lower than 5.5 had 2.5 times higher risk of developing diabetes than those with a pH above 6.5 [30].

4) Polycystic Kidney Disease

Polycystic kidney disease (PKD) is a genetic disorder that causes loss of kidney function. This results in a urine pH below 5.5 in the majority of people with PKD [31].

5) Mercury Toxicity

Mercury is known to cause damage to the kidneys [32].

In a study 200 workers constantly exposed to mercury, urine pH decreased with increasing levels of mercury in the urine [33].

Conditions Associated with Low Urine pH Levels

1) Kidney Stones

Low urine pH facilitates the formation of kidney stones. Acidic urine causes uric acid and calcium oxalate to clump together and form stones. This effect is seen with pH levels below 5.5 [22, 34, 21, 35, 36, 37].

2) Obesity and Excess Body Weight

Obesity and high BMI are linked to an increased risk of kidney stones. This may be due to reduced urine pH in obese and overweight people [38].

Higher BMI was associated with a lower urine pH in 460 men with kidney stones [39].

In a study of 342 people, urine pH was lower in obese and overweight people compared to normal body weight individuals [40].

In 13,895 men, urine pH below 5.5 was associated with obesity [41].

3) Metabolic Syndrome

Metabolic syndrome is a condition characterized by at least three of the following five features: high blood pressure, high blood sugar, excess stomach fat, high triglycerides, and low HDL cholesterol (HDL-C).

Urine pH below 6 was linked to excess fat around the stomach in 98 people with kidney stones [42].

In a study of 150 people, those with metabolic syndrome had an average urine pH of 5.8 compared to a urine pH of 6.1 for those without it. People who had all five features of the metabolic syndrome had a pH of 5.6 [43].

In a study of 5.4k people, those with metabolic syndrome had lower urine pH than those without metabolic syndrome. People with a urine pH below 5.5 were 52% more likely to have metabolic syndrome than those with a pH above 6 [44].

In 14.5k healthy people, urine pH below 5.5 was linked to a 48% increased risk of developing metabolic syndrome over three years compared to a pH above 6 [45].

High triglycerides, low HDL-C, and high blood sugar were linked to lower urine pH in a study of 22k people [41].

4) Non-alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is a buildup of fat in the liver due to causes other than excessive alcohol (diet, infections, drugs).

A study of 98 people found that a urine pH below 6 was linked to fatty buildup in the liver [42].

A urine pH below 5.5 was associated with a higher likelihood of NAFLD compared to a pH above 5.5 in a study of 1k people [46].

5) Narrowing of the Blood Vessels in the Kidneys

In 350 people with diabetes, lower urine pH was linked to an increased risk of developing narrowing or blockage of the blood vessels in the kidneys (renovascular disease) [47].

6) Advanced Chronic Kidney Disease

In a study of 1,800 people, those with urine pH between 5 and 5.5 had a 32% increased risk of developing advanced chronic kidney disease after 8 years [48].

Another study found that a pH below 5.5 was associated with an increased risk of advanced chronic kidney disease in 537 people with heart disease [49].

7) Bladder Cancer

A urine pH below 5 was linked to an 80% increased risk of bladder cancer in 1,300 people [6].

8) Risk of Dying From Heart Disease

Having a urine pH below 5.5 was linked to an increased risk of death due to heart disease in 537 people [49].

Ways to Increase Urine pH Levels

1) Exercise

Performing bench step exercises for 2 hours a week for 12 weeks increased the urine pH of 59 people [50].

Cycling until exhaustion increased the urine pH of six people [51].

Knee extension exercises increased urine pH for 2.5 hours post-exercise [52].

2) Diet

High fruit and vegetable intake and lower consumption of meat were linked to a more alkaline urine pH in 22,038 people [8].

Eighteen people who ate a diet high in vegetables and fruits and low in meats and dairy for three days had their pH increase from 6.5 to 6.7 [21].

Twenty-six people who ate a diet high in vegetables and fruits and low in meats and dairy saw their pH increase from 6 to 6.5 after three days [22].

As high-protein diets decrease urine pH levels, decreasing protein in your diet will reduce the acid load on the kidneys and increase your urine pH [23, 24, 25].

3) Citrate

Citrate binds with calcium and prevents it from crystallizing into stones. It also increases urine pH, further helping to prevent calcium from clumping together into stones [53].

One week of 4,500 mEq/day of potassium citrate increased urine pH [54].

One month of magnesium and potassium citrate increased urine pH in 61 people with kidney stones [55].

In a study of 21 people with kidney stones, 4,500 mg/day of potassium citrate for four days increased urine pH from 5.5 to 5.88 [56+].

One week of 4,500 mg/day of potassium citrate increased urine pH from 6.2 to 6.6 in 13 people [57+].

Note: Potassium supplements should be taken with caution and under medical supervision!

4) Magnesium Lactate

Magnesium lactate (175 mg/day) increased the urine pH of eight people [58].

5) Malic Acid

Malic acid is a compound that causes the sour taste of some fruits. It is also used as a food additive.

In a study of 8 people, supplementing with 1,200 mg/day of malic acid for seven days increased urine pH from 6.13 to 6.48 [59+].

6) Baking Soda

A single dose of baking soda (sodium bicarbonate) increased the urine pH of 65 people (0.3 gm/kg body weight) [60].

Drugs that Increase Urine pH

Drugs that can increase the pH of the urine levels include:

  • Aspirin [61]
  • Acetazolamide used to treat glaucoma, epilepsy, mountain sickness, and fluid retention [62]
  • Valproate (Convulex, Depakote, Epilim, Stavzor), acetazolamide (Diamox, Diacarb), and topiramate (Topamax) used to treat epilepsy and bipolar disorder [63, 62, 64]
  • The antibiotics trimethoprim and sulfamethoxazole [65]
  • Dexamethasone (Ozurdex, Decadron, Diodes, Hexadrol, Maxidex), a corticosteroid used to treat inflammatory disorders [66]
  • Lithium therapy used to treat mania associated with bipolar disorder (Carbolith, Duralith, Lithonate) [67]

Causes of High Urine pH Levels

1) Urinary Tract Infection

The most common cause of elevated urine pH levels is an infection in the urinary tract. Many of these infectious organisms produce an enzyme called urease that breaks apart urea to carbon dioxide and ammonia, increasing urine pH [68, 69].

2) Vomiting

Vomiting causes blood pH to increase, which the kidneys must counteract by releasing alkaline compounds in the urine. This increases urine pH and makes it alkaline [70].

3) Alcohol Abuse

Alcoholics are commonly found to have elevated urine pH due to damaged kidneys. In a study of 60 alcoholics, 22 had a urine pH greater than 6.4. After 30 days of no drinking, their pH returned to normal [71].

4) Respiratory Alkalosis

Respiratory alkalosis is a condition caused by low carbon dioxide levels in the blood due to breathing at a very fast rate (hyperventilation). It is usually caused by critical illness but can also be caused by many heart and lung disorders. Respiratory alkalosis results in a higher blood pH, forcing the kidneys to increase the urine pH to compensate [72].

5) Renal Tubular Acidosis

Renal tubular acidosis (RTA) is a group of disorders that change how the kidneys handle the balance between acid and bases. They can be caused by mutations, autoimmune diseases such as lupus and rheumatoid arthritis, toxins, and chronic kidney disease [73].

People with RTA commonly have elevated urine pH due to an inability to release acids in the urine [73, 74].

Conditions Associated with High Urine pH Levels

1) Kidney Stones

The risk of calcium phosphate stones increases as the urine pH rise from 6.5 to 7.5. High urine pH causes calcium phosphate to become concentrated and clump together [75, 14, 76, 77, 37].

In a study of 1,200 people with stones, those with the most calcium phosphate stones had the highest urine pH levels [78].

In 4,700 people who initially had calcium oxalate stones, those who went on to develop calcium phosphate stones had high urine pH levels [79].

Ways to Decrease Urine pH Levels

1) Diet

Two studies of 44 total people have found that diets high in meat and dairy and low in vegetables decreased urine pH by increasing the amount of acid made in the body [21, 22].

Multiple studies of 89 total people found that high protein diets make the urine more acidic [23, 24, 25].

2) Cranberry Juice

An 80% concentrated cranberry juice (5 – 8 oz) reduced urine pH levels in 21 people after 12 days [80+].

Drinking eight ounces of 25% concentrated cranberry juice reduced the urine pH of 21 people over 4 weeks [81].

3) Magnesium Glycinate

Magnesium glycinate decreased urine pH in 61 people with kidney stones [55].

Drugs that Decrease Urine pH

Drugs that can decrease the pH of the urine include:

  • Furosemide (Lasix), used to treat fluid retention and swelling caused by heart and liver disease [82]
  • Ammonium chloride, used in cough medicine [83]
  • Thiazide diuretics such as hydrochlorothiazide (Microzide), used to treat high blood pressure and fluid retention [84]
  • Methenamine mandelate (Hiprex, Mandelamine, Urex), an antibiotic used to prevent urinary tract infections [85]

Genetics of Urine pH

SNPs Associated with Higher Urine pH [86]:

  • rs6955765 (T>C)
  • rs145048940 (C>A)
  • rs34447434 (A>C)
  • rs17761305 (T>C)
  • rs28623722 (G>A)
  • rs28370990 (T>C)
  • rs17183073 (C>G)
  • rs768831 (A>G)
  • rs1713968 (A>G)
  • rs116189043 (A>G)
  • rs1611781 (G>A)
  • rs6554409 (C>T)
  • rs1713961 (C>T)
  • rs1718883 (T>A)
  • rs7670536 (T>C)
  • rs1713962 (G>A)
  • rs1718874 (C>T)
  • rs1713967 (T>A)
  • rs1718873 (C>T)
  • rs13107451 (A>G)
  • rs11726321 (C>T)
  • rs77053948 (G>A)
  • rs1718834 (T>C)
  • rs1718872 (C>G)
  • rs6817232 (G>C)

Polycystic kidney disease is a genetic disorder that causes low urine pH and is caused by the PKHD1 gene and mutations in PKD1 or PKD2 genes [87].

Renal Tubular Acidosis

Renal tubular acidosis, which results in alkaline urine, may be caused by mutations in the following genes [88+]:

Irregular Urine Levels?

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About the Author

Will Hunter

BA (Psychology)
Will received his BA in Psychology from the University of California, Los Angeles. 
Will's main passion is learning how to optimize physical and mental performance through diet, supplement, and lifestyle interventions. He focuses on systems thinking to leverage technology and information and help you get the most out of your body and brain.

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