Staying hydrated is critical for Service Member health and mission readiness. This concept is well recognized across the DoD, which is why you’ve probably seen urine color (Uc) charts posted in bathroom stalls across your installation. Even though using Uc is a common practice to assess hydration status, you may not be getting an accurate estimate because you may be using the wrong tools. Variations in Uc charts and inconsistent application of the charts can compromise the accuracy and reliability of these tools. By better understanding the validated Uc charts and how to properly use them, you can get a better picture of your hydration status.
Validated urine color charts
Uc charts were developed so that you can visually compare the color of your urine to a series of standardized shades, allowing you to accurately evaluate your hydration status. However, to get an accurate picture of your hydration levels, you should be using a validated Uc chart.
Using validated charts is important because it means that you can feel confident the results will be accurate and trustworthy. Research studies have been done to ensure that these charts can assess hydration status with an accuracy similar to other more complex hydration measures. If you’re not using a validated Uc chart, you may not be getting a good estimate of your hydration status. Three validated Uc charts have been developed and tested for accuracy in military populations:
Armstrong’s 8-color chart (1994) was the first validated Uc chart that demonstrated a strong correlation between urine color and blood markers of hydration status. As the title suggests, this Uc chart consists of eight standardized color strips ranging from pale yellow (well-hydrated) to dark green (severely hypohydrated). To use this chart accurately, collect a sample of your urine in a clear cup and compare it against the Uc chart.
Wardenaar’s 7-color chart (2019) was more recently validated. This Uc chart features a gradient of seven distinct colors ranging from very light yellow (well-hydrated) to deep amber (severely hypohydrated). To use this chart accurately, collect a sample of your urine in a clear cup and compare it against the Uc chart.
Wardenaar’s 3-color lavatory chart (2021) is another recently validated Uc chart that uses a three-color panel to assess urine directly from the toilet bowl, eliminating the need to collect a sample in a cup. However, to use this chart accurately, you also have to time your urine stream (in seconds). After timing the duration of your urine stream, select the chart color that correlates with the duration time. Then compare this reference color to the urine color in the toilet bowl. If your urine color is lighter or similar to the reference color, you are well-hydrated. If your urine color is darker than the reference color, you are hypohydrated.
It’s important to remember that even if you’re using a validated Uc chart, to get accurate results, it’s best to follow the validated methods for accurate results. For example, it’s common to see Armstrong’s 8-color urine chart (a validated chart) hanging in toilet stalls. Yet, this color chart is only valid, meaning the color accurately represents your hydration status, when urine is collected in a cup, not diluted in a toilet bowl. Therefore, using this chart after urinating in a toilet bowl (unvalidated method) makes the results less accurate. While using Armstrong’s 8-color urine chart after urinating in a toilet bowl can still provide general hydration awareness, it would be more accurate to use Wardenaar’s 3-color lavatory chart, which was validated to assess urine color after diluted in a toilet bowl.
Overview of how to best use Uc charts
To accurately assess your hydration status using these validated Uc charts, follow the methods and recommendations below.
*Armstrong 8-color Uc is also used when applying the WUT method to assess hydration.
Other factors that might influence urine color assessment
Other factors can influence the accuracy of urine color charts for assessing your hydration status.
- Environmental light can change the color appearance of your sample. For increased accuracy, try to conduct assessments under standard conditions, such as a small LED flashlight
- Collection time and method can influence assessment accuracy. If possible, collect urine samples at the same time of day and use the same collection method (toilet bowl or collection cup). Perceived color can be influenced by the container material and volume.
- Printer ink quality and varying digital screens can influence the accuracy of your reading. Since there is some variability in printer calibration, ink quality, and monitor screens, the color shades of the charts might vary, altering the accuracy of the assessment.
- Individual physiological factors, such as age and amount of muscle mass can influence urine color. Generally speaking, increased age and muscle mass can lead to slightly darker urine color.
- Diet and supplements may influence urine color. For example, B-vitamins can commonly lead to bright yellow urine, or beet consumption can lead to darker urine.
- Clinical conditions, like exertional rhabdomyolysis (muscle breakdown from intense exercise), can lead to urine color alterations—most commonly, the appearance of cola-colored urine. Be sure to see your medical provider if you experience this.
Summary
Uc charts can serve as a valid and practical measure of your hydration status. However, to increase accuracy, it’s important to use the appropriate Uc chart and correct method based on your situation. Understanding your hydration status can help you optimize your hydration strategies and increase mission safety, performance, and effectiveness. If you have more questions about your hydration status, or the use of Uc charts, reach out to your local medical provider, registered dietitian, or human performance team.
