Checking for ketones
By Beth Zupec-Kania, RDN, CD
A frequently asked question when starting a ketogenic diet therapy is “how do I know I’m in ketosis?”. There are three different methods for checking and monitoring ketosis. I’ll explain each then give examples of how my patients have selected the one to best suit their needs.
Urine ketones (acetoacetate); the simplest and cheapest but least accurate of all methods. This method may be “good enough” for most people who are monitoring themselves at home and are able to get a more specific level at their doctor’s office. The reason that urine ketones are not precise it measures the ketone called acetone that is cleaned out of the blood by the kidneys. Another reason is that the amount of liquid that you drink can change the reading. If you are drinking very little an hour before you check, the urine ketone reading can appear strong on the urine test-stick because they are concentrated. If you are drinking a lot before you check, the ketones can appear weak because they are diluted.
Example: I’m working with a 5-year-old who started on ketogenic diet therapy over a year ago for epilepsy. Our plan was to start with the simplest method of checking ketones and if needed, we’d graduate to another method during “fine-tuning” of his diet to achieve better seizure control. After three months on the diet his seizures stopped completely, no diet changes were needed and so there was no reason to change to another method of checking ketones.
Products: there are only a few different companies that make urine ketone test strips. The One Earth Health brand is the most reasonably priced. My patients like the color chart on the bottle which shows an estimate of the blood ketone betahydroxybutrate along with the urine reading.
Blood ketones (betahydroxybutryate); this method has an advantage over urine ketones in that it reveals ketosis in real time and is not affected by the amount of liquid that you drink. The betahydroxybutryate (or BOHB for short) level also correlates to blood glucose which can be helpful in adjusting the diet. The lower the blood glucose, the higher the BOHB level. For this reason most of my patients prefer to check both levels simultaneously. If you are taking exogenous ketones of salts or esters that are primarily the L-BOHB, the meter will not detect that version.
Example: An adult client of mine, who is using ketogenic diet therapy as a complimentary treatment for her brain cancer, uses a meter to check ketones and glucose. Tracking both metrics over time has helped us to modify her diet to achieve consistency in lower glucose and stronger ketones.
Products: there are only a few companies that make a meter that can check both glucose and ketones. Meters are generally inexpensive but the disposable strips can be cost prohibitive. Many of my clients have chosen KetoMojo because the strips are less costly. Their meter also reads hemoglobin and hematocrit levels which other meters don’t do.
Breath ketone (acetone)also called “exhaled ketones” is the third method that is available for checking ketones. This method evaluates ketones released from the lungs when you exhale and is easily analyzed by breathing into a tube.
Example: A client with diabetes who exercises regularly prefers this method of monitoring ketosis in addition to checking his glucose. He found that breath acetone was more consistent during exercise than when he checked his betahydroxybutrate which decreased during his exercise but increased later.
There are companies that make portable ketone breath analyzers. KEYTO is a brand that my patients have found helpful. It comes with an App that you sync the device to.