Ketone Testing Accuracy: Urine vs Blood
- Last updated October 5, 2020
Acetoacetate (AcAc): When glucose is no longer available as a primary source of fuel, fat is broken down by the liver into fatty acids, which are further broken down into ketone bodies. Acetoacetate is the first ketone body that is produced and is spilled into your urine, especially in the early stages of ketosis, but rarely in later stages.
Beta-hydroxybutyrate (BHB): BHB is the most prevalent and stable ketone body and is found in blood. It is readily transported to cells to use as fuel. It can fuel most of the brain’s energy needs along with organs and muscles and represents approximately 70% of the available ketone energy.
Urine strips were designed primarily to monitor diabetic ketones in order to help prevent diabetics from unknowingly getting into ketoacidosis. Not to be confused with nutritional ketosis, ketoacidosis is a very serious metabolic state caused by insulin deficiency that occurs when high ketone levels are present with very high glucose levels. As a result, urine strips are effective in helping diabetics avoid a dangerous state. However, because urine strips measure excess or excreted ketones in the urine, they are inaccurate in determining nutritional ketosis and how well your body is utilizing ketones as fuel.
When first transitioning to ketosis, sometimes the body will make excess acetoacetate ketones, which will show up in your urine and on urine strip tests. If you get a reading for high ketones early on with a urine strip, it’s a sign that you are producing ketones but not an accurate measurement of your level of ketosis (ketones in your blood). Try the same test a few weeks later while maintaining a keto diet and your urine test may reveal no ketones, even if you are actually in ketosis. As your body becomes fat-adapted, it converts ketone bodies more efficiently and is less likely to expel them.
Accuracy with urine tests for ketones can also be affected by your level of hydration; varying levels of hydration may result in inconsistent results. In addition, the readings are somewhat subjective when comparing the color on the strip to the color on the package. And the reading you get is not a reading at the moment in time, it’s the sum of ketones present since your last urination.
Bottom line: urine strips are a great way to know that you are starting to produce ketones in your first few weeks of following a ketogenic diet but not an accurate measurement of nutritional ketosis. If you plan to follow a ketogenic diet for more than a few weeks, and we highly recommend you do, then we recommend you invest in a blood ketone and glucose meter where you will be able to more accurately measure your level of ketosis and the foods that affect you. Fortunately, Keto-Mojo has the leading blood ketone and glucose meter on the market! Look no further…SHOP HERE.