Keto-adapted, but no ketones?

One of the cheapest and easiest ways to measure ketones would be to utilize ketone test strips, e.g. Ketostix. Ketone test strips use a chemical reaction to measure acetoacetate (see below), usually in urine, although the exact same method may be used for blood. (Not to be confused with the blood strips used in home for beta-hydroxybutyrate.) But, acetoacetate test strips are of limited usefulness. For one thing, urine concentrations are influenced by dilution, meaning they are influenced by how much you drink.

But the problem is deeper than that. Acetoacetate is but one of the 3 ketone bodies (see below). Initially, when you begin a ketogenic diet, acetoacetate will make up about half of the circulating ketones [1], but if you’re keto-adapted, it constitutes only about 20 percent of the ketone bodies in circulation (see below). Morover, the sensitivity of these strips is a little lower than ideal for our purposes. They enroll negative unless the concentration is high.

So, it is not uncommon for a keto-adapted person to measure negative for acetoacetate.

Different ketone bodies occur in different amounts

There are three compounds grouped together as ketone bodies: acetoacetate, beta-hydroxybutyrate, and acetone. In keto-adapted people, acetoacetate levels are relatively low even though beta-hydroxybutyrate is high. Normally, beta-hydroxybutyrate amounts are 4times as large as acetoacetate. (Acetone constitutes only about 2% of total ketone bodies [2].)

Beta-hydroxybutyrate and acetoacetate in blood and cerebrospinal fluid during fasting

The chart above shows that from the ketosis of fasting, the proportion of acetoacetate (the top, white part of the bar) is considerably smaller than that of beta-hydroxybutyrate (the black part). In the analysis here, after 21 days of fasting, the average amount of blood acetoacetate was 1.04 mmol/L, while the beta-hydroxybutyrate level was 4.95 mmol/L [3]. In another study of epileptic children on ketogenic diets, after 3 months, the average acetoacetate level was 1.182 mmol/L, while the average beta-hydroxybutyrate amount was 4.21 [4].

The amount of ketosis in fasting and in epileptic treatment is a little bit higher than for the typical ketogenic dieter who is simply trying to lose weight, improve athletic performance, or enhance their cardiovascular risk profile, for example. In those situations, beta-hydroxybutyrate amounts are typically 1–3 mmol/L.

Since the proportion of acetoacetate into beta-hydroxybutyrate is simply about 1:4, acetoacetate amounts will probably be only about 0.25–0.75 mmol/L for keto-adapted people. The acetoacetate measure doesn’t enroll as positive until about 0.5-1.0 mmol/L [5], so those values will often register as negative for acetoacetate.


Below are a few examples of negative acetoacetate, even while beta-hydroxybutyrate is very high.

There is a dangerous condition that diabetics can get into called keto-acidosis, that’s crucially different from supplements ketosis (a secure and wholesome condition ), but is often confused with it, since they both involve activation of ketogenesis. Ketone levels in keto-acidosis are much higher than in nutritional ketosis, and it’s the monitoring of the state that ketone strips are optimised for. Even though ketone levels in keto-acidosis are higher compared to nutritional ketosis, in 1 report it was found that 57% of diabetics with negative acetoacetate dimensions were suffering from keto-acidosis [6].

ketosis false negatives using urine acetoacetate

Most of the cases of high beta-hydroxybutyrate in this study were not also positive for urine acetoacetate.

This flowchart shows it is clinically accepted that even with very high beta-hydroxybutyrate amounts, acetoacetate in urine and blood may be negative. The reason why acetoacetate is bothered with at all is it is relatively cheap and easy to measure.

What is the best way to quantify ketosis?

Ketone test strips are a cheap and easy way to verify ketosis when you have very high levels, like during keto-adaptation. However, we would anticipate the false negative rate to be high for keto-adapted people, and for babies, (who are normally in consistent but mild ketosis while exclusively breastfed). So although it can be a good tool when you are starting a ketogenic diet, it’s not necessarily reliable as you progress.


A negative acetoacetate measure doesn’t imply that you are not in ketosis.


If you are troubleshooting, and need more precise measurements, we strongly recommend a blood ketone meter for beta-hydroxybutyrate. However, bear in mind that the strips themselves are extremely expensive.

A new breath acetone meter is now on the market. It costs about $100, but it does not demand any strips, so you pay just once. Unfortunately, like the acetoacetate strips, the step is just semi-quantitative, and appears to have a relatively substantial minimum threshold for showing positive. We also do not know how well acetone correlates to beta-hydroxybutyrate, or to curative outcomes. Nonetheless, it’s a promising technology, and it needs no pinpricks or trousers down. We’d like to hear from you if you’ve given it a try.

References:

[1]

Evidence type: authority

“Beta-hydroxybutyrate and acetoacetate are made from the liver in about equal proportions, and both are originally immediately oxidized by muscle. However, over a matter of weeks, the muscles stop using these ketones for fuel. Instead, muscle cells consume acetoacetate, reduce it to beta-hydroxybutyrate, and return it back into the circulation. Thus after a couple weeks, the predominant form in the flow is beta-hydroxybutyrate, which also happens to be the ketone preferred by brain cells (alternatively, the strips that test for ketones in the urine detect the presence of acetoacetate, not beta-hydroxybutyrate). The result of this practice of keto-adaptation is an elegantly choreographed shuttle of gas from fat cells to liver to muscle to mind.”

[2]

Evidence type: authority

Richard A. McPherson, Matthew R. Pincus
Elsevier Health Sciences, Sep 6, 201

“Whenever a defect in carbohydrate absorption or metabolism or an inadequate amount of carbohydrate is present in the diet, the body compensates by metabolizing increasing amounts of fatty acids. […] In ketonuria, the three ketone bodies present in the urine are acetoacetic acid (20%), acetone (2 percent ), and 3-hydroxybutyrate (about 78%).”

[4]

Evidence type: experiment

Neal EG1, Chaffe H, Schwartz RH, Lawson MS, Edwards N, Fitzsimmons G, Whitney A, Cross JH. doi: 10.1111/j.1528-1167.2008.01870.x.

“One hundred forty-five children with intractable epilepsy were randomized to receive a classical or an MCT diet.”

[…]

“Classical diets were started at a 2:1 ratio and slowly increased to a 4:1 ratio as tolerated over 1–2 weeks; at a few kids the ratio was kept at 3:1 for more due to tolerance problems. Protein was generally kept at World Health Organization (WHO) minimum requirements for age (World Health Organization, 1985). MCT diets were commenced on a complete prescription for carbohydrate (generally 15% energy), protein (usually 10% energy), and long-chain fatty acids (usually 30% energy). The MCT fat was increased incrementally over a 7–10 day period as tolerated, to a initial level that was usually 40–45% of total dietary energy. Diets were supplemented with vitamins and minerals.

“Subsequent to beginning the diet, all kids were reviewed as outpatients at 3, 6, and 12 months. They were also closely monitored by telephone between clinic visits. Diets were fine-tuned as necessary to improve ketosis and optimize seizure control. The parameters within which the two diets could be modified were defined before study commencement. Overall energy prescription was corrected on both diets as needed. Ketogenic ratio on the classical diets had been kept between 2:1 and 5:1 (most classical diet kids were on a 4:1 ratio, a few were on a 3:1 ratio, and two kids needed a 2:1 ratio for a short period). Fine-tuning on the MCT diets included adjusting the ratio of MCT and carbohydrate in the prescription. MCT was usually started at 40–45 percent of energy, and has been increased up to 60% if necessary and tolerated. Carbohydrate was usually started at 15% of energy, and has been reduced to a lowest value of 12 percent if necessary. Carbohydrate was reduced to improve ketosis only if an increase in MCT was not possible because of poor tolerance. Other modifications on both diets were fluid intake and meal distribution. Protein intake was increased as needed to meet requirements.”

https://lh3.googleusercontent.com/-GFZldRQ9ZJ8/U0K3Tz42-4I/AAAAAAAAB5Y/GcRiXEaYAGc/w775-h555-no/epilepsy-acetoacetate-beta-hydroxybutyrate.png

[5]

We have seen claims that they can detect as little as 5 mg/dl (0.5 mmol/L), only 10 mg/dl, or, most commonly, the minimum is given as the range 5–10 mg/dl. Here’s an example of each:

3rd edition.

Walker HK, Hall WD, Hurst JW, editors. Boston: Butterworths; 1990.

“Nitroprusside is available as an evaluation pill (Acetest) and as a coated reagent strip (Ketostix), both manufactured by the Ames Division of Miles Laboratories, Inc., Elkhart, Indiana. With Acetest, after 30 seconds the color development is compared to a graph and judged negative, small, medium or large. The tablet will detect 5 to 10 mg/dl of acetoacetate and 20 mg/dl of acetone. The quantitative range included in each class is 5 to 20 mg/dl for small, 20 to 40 mg/dl for medium, and 40 mg/dl or greater for large. With Ketostix, the strip is momentarily dipped into the urine specimen or passed in the urinary stream and compared to a color chart 1 minute later. The scale is negative, trace, small, medium, and large. The strip is capable of detecting 5 mg/dl acetoacetate but isn’t reactive to acetone. The ranges are wider and shifted somewhat to the right in the higher zones compared to Acetest so that just 16% of samples containing 20 mg/dl acetoacetate are read as moderate while 24% of samples containing 80 mg/dl acetoacetate are still called moderate. Only 15% of the samples containing 40 mg/dl acetoacetate are judged to be large; 76 percent are big at 80 mg/dl and 100% at 160 mg/dl. The Ketostix test is most accurate when urines are analyzed with a high specific gravity (between 1.010 and 1.020) and low-pH. Highly pigmented urine specimens may yield false positive readings. Levodopa will also cause a false positive outcome. Ketostix strips are less sensitive than Acetest tablets and possess a high level of variability between lots. Acetest, with sensitivity at the 5 mg/dl range, is the preferable method.”

Ochei Et Al.. Aug 1, tata McGraw-Hill Education, 2000. p 134

“Ketostix (Ames)

This test strip will discover 0.5–1.0 mmol/L (5–10 mg/dl) of acetoacetic acid”

Shelly L. Vaden, Joyce S. Knoll, Francis W. K. Smith, Jr., Larry P. Tilley
John Wiley & Sons, Jun 13, 2011

“Just acetoacetate and acetone are detectable by reagent strips or pill tests, which are based on the reaction of acetoacetate (more reactive) and acetone (less reactive) with nitroprusside.

“Urine (and blood) can be screened for ketones by using either reagent strips or tablets […] The [tablet] is more sensitive than reagent strips and will detect 5 mg/dL of ketones compared with 10 mg/dL for dipsticks.”

[6]

Proof type: jurisdiction, since we can not access the full text

Yutaka Harano, M.D., Masaaki Suzuki, M.D., Hideto Kojima, M.D., Atsunori Kashiwagi, M.D. Ph.D., Hideki Hidaka, M.D. Ph.D. and Yukio Shigeta, M.D. Ph.D..
Diabetes Care September/October 1984 vol. 7 no. 5 481-485

“MacGillivray et al. recently reported that 57 percent of the urine tests that were negative for ketone bodies by acetest were associated with elevated plasma 3-OHBA in insulin-dependent diabetes.

[…]

“MacGillivray, M. H., Voorhess, M. L., Putnam, T. I., Li, P. K., Schaefer, P. A., and Bruck, E.: Hormone and metabolic profiles in children and adolescents with Type I diabetes mellitus. Diabetes Care 1982; 5(Suppl . l):38-47”

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