Should I use Ketone Urine Strips to Measure Whether I am in Ketosis?

Keto4Life

Well-known member
May 24, 2021
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A common question for individuals implementing a ketogenic diet for weight loss and/or for general health and specific medical conditions is; how do I know when I am in ketosis? There are a few ways that ketones in the body can be measured, but they each measure different types of ketones in the body.

There are three different types of physiological ketones that can be measured and they are measured by three different commonly available methods. The three ketones and methods of measuring them are:
  • Beta-hydroxybutyrate - Beta-hydroxybutyrate (BHB) is measured in the blood and is the majority of the circulating ketones found in the body (~78%).
  • Acetoacetate - Acetoacetate (AcAc) is measured in the urine and is the second most abundant ketone in the body (~20%).
  • Acetone - Acetone is measured in the breath and is the least abundant ketone in the body (~2%).
BHB is the main ketone in the body and can be measured with a handheld monitor such as the Precision Xtra or Keto-mojo monitors. The most commonly used monitor observed being used in studies is the Precision Xtra monitor. Measuring blood ketones is considered the most accurate way to measure a person’s current level of ketosis. Before the explosion of interest in the ketogenic diet, these monitors were primarily used by diabetics to track and prevent entering into a pathological state of diabetic ketoacidosis (DKA) vs. the healthy levels of ketones (nutritional ketosis) that are found in people with healthy insulin production. Individuals with a healthy functioning pancreas will naturally limit the production of unhealthy levels of ketones via the production of insulin.

Acetone is a byproduct of the breaking down (decarboxylation) of acetoacetate in the body and has been found to have its own unique physiological effects on the body, however acetone is the least abundant ketone in the body. Acetone is measured in exhaled breath and there are breath monitors readily available in the market now to measure the concentration of acetone in the breath such as the Ketonix or Biosense meters.

The focus of this discussion is on acetoacetate as it is measured in the urine using commonly found and inexpensive ketone urine dipsticks such Ketostix. As ketone urine strips are cheap, non-invasive and easy to use, it’s natural to want to gravitate to this method to measure whether you are in ketosis or not. But, is this method a reliable way to check ketone levels?

Though it is natural to want to use ketone urine dipsticks to know whether you are in ketosis, there are several factors that support the fact that this method is not a very effective way to measure your level of ketosis. In fact, this method can give a misleading or false indication of the presence of a being in a ketotic state.

Predictably, when a person first begins a ketogenic diet and begins producing ketones, the circulating ketones produced will build up to a point that the kidneys will excrete them in the form of acetoacetate in the urine. This is indeed an indication that insulin levels have dropped to a level sufficient to produce ketones and that one has entered into ketosis. However, there is more to the story.

A study conducted in Australia and published in May of 2020 (Urine dipsticks are not accurate for detecting mild ketosis during a severely energy restricted diet) examined the accuracy of using ketone urine dipsticks to detect mild ketosis. Though the study assessed the accuracy of the pee strips in a group of women (aged 45-65 years) using a “severely energy-restricted diet” (630-780 kcal/day) versus a more traditional method of entering ketosis with a higher calorie content ketogenic diet, the results can safely be extrapolated. The stated objective of the study was: “To determine the accuracy of urine dipsticks to detect mild ketosis during adherence to a severely energy-restricted diet.”

The researchers measured ketone levels in the participants before and during sixteen weeks of a severely energy-restricted diet. Blood ketones (BHB) were measured concurrently using a FreeStyle Optium ketone monitor and compared to measurements of AcAc measured via urine strips (Ketostix). “There were 263 data points in which participants had both a urine dipstick and blood monitor ketone measurement that could be used for analysis in the present study.”

The data collected revealed up to “65% of the times when participants were actually in ketosis, as defined by their blood β-hydroxybutyrate concentrations being at or over these 0.3 and 0.5mM thresholds, the urine dipstick indicated that they were not in ketosis.” So, essentially for the moderate levels of ketosis (≥ 0.5 mmol/L) that most ketogenic dieters will see, the urine strips are not the best choice. However, for higher concentrations of ketones that are of concern to individuals with diabetes, the urine strips were found to be “acceptably accurate in the context of detecting diabetic ketoacidosis”. On the other hand, the authors note that “previous research has shown blood β-hydroxybutyrate monitors to be highly accurate compared with laboratory enzymatic analysis.”

There are a few factors suggested for why ketone urine strips may not be a reliable method of measuring ketones for individuals implementing a ketogenic diet that include:
  • As the body becomes more efficient at using ketones for energy it will increasing upregulate the necessary enzymes transporters to utilize ketones. This is a natural process that happens as one becomes fat-adapted. As the body becomes incresingly fat-adapted (becoming more efficient at utilizing fat for energy), more ketones will be used to fuel the processes in the body and therefore fewer ketones will be spillover into the urine.
  • A person’s level of hydration will also effect the concentration of ketones in the urine.
Conclusions
To sum it up, ketone urine test strips are a cheap method that will provide a fair indication of whether or not a person just starting on a ketogenic diet is in ketosis and is also a reliable method for diabetics seeking to monitor and avoid Diabetic Ketoacidosis. Ketone blood monitors provide the most reliable method of checking real-time ketone levels of the most abundant form and more clinically relevant of ketones (BHB) in the body with ketone monitors reassuringly being “shown to be highly accurate in comparison with laboratory-determined blood β-hydroxybutyrate concentrations.”

The authors final conclusion from this study states:

“Urine dipsticks are not an accurate or clinically useful means of detecting mild ketosis in people undergoing a severely energy-restricted diet and should thus not be recommended in clinical treatment protocols. If monitoring of mild ketosis is indicated (eg, to monitor or help promote adherence to a severely energy-restricted diet), then blood monitors should be used instead.”