Does Urine Hold DNA for Analysis?


Deoxyribonucleic acid (DNA) is the molecule that holds all the information needed to make each person unique. DNA is found in the cells of nearly every part of your body.

Today, DNA is used to investigate and prove crimes, identify a person’s genealogy, prove identity, or even diagnose bladder cancer.

But can DNA be found in urine, and can it be used for at-home DNA tests or even DNA paternity testing? Keep on reading. We will tell you everything.

Obtaining a Quality DNA Sample

Even a tiny sample of DNA is enough to use as evidence. DNA samples are also viable for many years after they are collected if the proper collection and storage methods are used. Exposure to UV light, moisture, and room temperature are some things that can cause DNA to degrade.

The source of the DNA depends on the reason for the DNA testing. For example, law enforcement often tests DNA for forensic purposes. When the person being analyzed is unknown, some of the most common sample sources include:

  • Dried blood stains on clothing, bandages, tissue, etc.
  • Dried semen stains on clothing, bed linens, used condoms, etc.
  • Dried saliva on cigarette butts, bite marks, napkins, drink containers, etc.
  • Sweat on clothing, eyeglasses, weapons, etc.
  • Dried stains on underwear, personal hygiene products, etc.

Forensic testing depends on what, if any, DNA sample is available. In contrast, saliva is often the primary source of DNA when collecting a sample from a known person. This method is non-invasive, totally painless, and straightforward.

When saliva tests are performed for genealogy, you will typically spit into a small container and seal it. However, in a lab where technicians obtain the saliva sample for any purpose, the most common method of collection used is the oral buccal swab method.

For this test, a swab resembling a one-ended Q-tip is placed between the cheek and the upper gum. The technician then rubs the swab back and forth and swirls it to collect an accurate number of cells.

Protecting DNA Samples

The single biggest issue that affects a DNA sample is contamination. This happens when other DNA samples get mixed in. For example, if someone coughs or sneezes over the evidence or they transfer their cells by touching their body and then touching the sample, it can result in contamination and an inaccurate result.

The Role of DNA Markers

A DNA marker is a sequence with a known physical location on the chromosome. Markers serve as “landmarks” to create a map that detects other genes. When markers are close to a gene, they are typically inherited together. Markers provide a location for a gene that hasn’t yet been identified.

These markers are measured through the blood using blood cells and epithelial cells. The latter are cells found in the outer layer of your skin. These are some of the issues that make urine a less reliable source of DNA.

A Comparison to Urine-Related DNA Samples

Many people wonder, “does urine hold DNA?” Of course, there is DNA in urine, but there isn’t as much as in saliva, blood, or semen.

The DNA found in urine is directly related to the epithelial cells present. The lower volume of DNA in urine makes it more challenging to extract it from a urine sample.

Human DNA also breaks down faster in the urinary tract, making it difficult to extract the needed biomarkers. However, when urine is the only source of DNA for use in forensics, it can be a valuable resource.

DNA Extraction from Long-Term Stored Urine

There has been some promise of collecting good DNA samples from urine even after long-term storage. However, normal storage conditions such as those used for saliva swabs aren’t practical for urine samples. Unique issues make storage more challenging. For one, males tend to have more DNA present in first-morning urine, while females produce higher yields in the afternoon.

Necessary storage temperatures for urine also cause more challenges. Samples are best preserved using -80° freezers. Since first or second morning samples appear to have the highest yields, available storage is essential for maintaining the integrity of the samples.

A urine specimen that is filtered and freezes dried can provide high yields of DNA after years of storage. This process does provide an option where urine is the only DNA source available.

The Place for Urine DNA Analysis

Urine-related DNA testing is an option for cases where no other samples are available. Also, they might aid in the diagnosis of certain diseases and conditions.

DNA technology continues to grow, leaving the door open for more accurate and valuable urine-based DNA tests in the future. But, for now, the most accurate testing on known individuals uses saliva and blood tests.

Even when these methods are used, choosing a professional quality lab is essential. In addition, knowledge of the collection, extraction, testing, and storage of DNA helps ensure an accurate result.

Was this article helpful?