Nitrates in Urine

Introduction

A urine test or urinalysis is performed to identify the components of the urine. The result of the urinalysis will be able to provide some information about a disease condition an individual may have.

Nitrates is one of the components that may be found in the urine that may or may not be indicative of a pathologic condition [1, 2].


What are nitrates in urine?

Nitrates are usually found in the urine because it is the primary way of the body to excrete these compound. The source of these nitrates are plants and vegetables that are ingested by the individual.

Once these are metabolized, the nitrates that has been accumulated is then excreted through the urine.[3, 4, 5].

Causes of Nitrates in Urine

Dietary Intake

The primary source of nitrates is the diet. Vegetables such as celery, spinach, red beetroot and lettuce have higher levels of nitrates.

Meat and meat products especially those which are preserved with sodium nitrates increases its amount in the body. Nitrates is also one of the most common preservatives used in commercially-prepared baby foods [6].

The increased amount of nitrates in the plants that are eaten may be a cause of concern because inorganic nitrates that are typically found in contaminated soil are absorbed by vegetables such as green, leafy vegetables and beetroots.

Water sources can also be contaminated by nitrates and it can be consumed as well. Ingesting high amounts of nitrates cause problems such as nitrate toxicity that is very harmful especially to infants [6].

Medications

Taking medications that contain nitrates may increase the amount of this compound in the blood. Examples of these medications include nitroglycerin, Quinone derivatives antimalarial and some vasodilators such as isosorbide dinitrates [6].

Urinary Tract Infection

As mentioned earlier, nitrates is commonly found in the urine. These nitrates however are converted to nitrites by bacterial enzymes possessed by gram negative bacteria.

A positive nitrite test is indicative of a urinary tract infection. On the other hand, there are pathogens such as the Salmonella, Proteus, Clebsiulla, and Citrobactor who are unable to convert nitrites to nitrates. Because of this, an individual may experience signs and symptoms of UTI but will present a negative nitrite test [4].

Inflammatory Bowel Disease

The primary source of nitrate is usually from the ingestion of food and medications that contain this compound. A research done on patients with an inflammatory bowel disease shows that increased amount of urinary nitrate is present in these individuals due to the immune activation of the endogenous nitrate synthesis [7].


Clinical Significance of Nitrates in Urine

Nitrates are compounds that are commonly found in food such as plants and preserved foods. Produce that are harvested from soil that are contaminated with high levels of nitrates.

If these foods are ingested by an individual, this may lead to abnormally high levels of nitrate in the blood and eventually to nitrate poisoning. It is essential to ensure that the produce that is consumed is not treated with nitrate fertilizers to avoid ingesting high amounts of these compounds [4, 6].

Commercially-prepared infant foods contains nitrates which put the children at risk. Drinking water may also contain nitrates and these may be unknowingly given to them. High levels of nitrates in children will lead to problems with their oxygenation and may cause the “blue baby syndrome.”

Food and water that are given to infants must be ensured to be free from nitrate contamination. As much as possible, home prepare any baby food to avoid nitrate-preserved food. Bottled drinking water are regularly monitored by the government to ensure that they free from any nitrate [4, 6].

Individuals who are experiencing symptoms of urinary tract infection such as painful urination but has a negative nitrite test should undergo further tests. The pathogen that causes the infection may not be able to convert the nitrate to nitrite, hence the false negative reading.

The antibiotic course of treatment must be completed to prevent the infection from reoccurring. Increasing the intake of water will also be helpful in excreting the bacteria out of the urinary system [4].


References

  1. (2014, September 9). Urine Test. Retrieved from WebMD: http://www.webmd.com/a-to-z-guides/urine-test
  2. (2015). Urinary Nitrites and Leukocyte Esterase. Retrieved from RNceus: http://www.rnceus.com/ua/uanile.html
  3. Labtests Online. (2015). Retrieved from Labtests Online: https://labtestsonline.org/understanding/analytes/urinalysis/ui-exams/start/1#nitrite
  4. (2015, October 21). Nitrates or Nitrites in Urine. Retrieved from Minimedia: http://minimemedia.com/nitrates-in-urine/
  5. Kobayashi, J., Ohtake, K., & Uchida, H. (2015). NO-Rich Diet for Lifestyle-Related Diseases. Nutrition, 4911- 4937.
  6. Agency for Toxic Substances & DIsease Registry. (2013, December 5). Where Are Nitrates and Nitrites Found? Retrieved from Agency for Toxic Substances & DIsease Registry: http://www.atsdr.cdc.gov/csem/csem.asp?csem=28&po=5
  7. Melichar, B., Karlicek, R., & Tichy, M. (1994). Increased Urinary Nitrate Excretion in Inflammatory Bowel Disease. European journal of clinical chemistry and clinical biochemistry, 3-4.

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