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Immunology & Autoimmune
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This blood test measures beta-hydroxybutyrate, the main ketone body your body produces when it shifts from using sugar to using fat for energy. That shift can happen with fasting, low carbohydrate intake, prolonged exercise, illness, or when insulin is not working well. The result reflects how much ketone is circulating in your blood at the time of the draw.
Compared with urine ketone tests, a blood beta-hydroxybutyrate measurement gives a more direct and timely picture of your current ketone status. Clinicians use it in emergency and outpatient settings to assess ketosis and to monitor how ketone levels change with treatment.
Ketones provide an important fuel source, but very high levels can signal ketoacidosis, a serious condition that can occur in people with diabetes and sometimes with certain medications. Measuring beta-hydroxybutyrate helps your care team evaluate symptoms such as nausea, vomiting, abdominal pain, rapid breathing, or dehydration, and to distinguish simple ketosis from ketoacidosis.
This test is also useful in other settings where ketones rise, such as prolonged fasting or malnutrition, heavy alcohol use, or severe vomiting in pregnancy. It helps guide treatment decisions and shows whether therapy is working as levels move toward your usual baseline.
Your result is interpreted in context with your symptoms, medical history, and other labs. Higher values suggest a greater degree of ketosis. Some increase can occur with fasting, low carbohydrate diets, or strenuous exercise and may be expected if you are intentionally following such a plan. If you have diabetes and feel unwell, rising ketones may indicate that your body is not getting enough insulin or is under stress from illness.
If your level is elevated and you have symptoms like abdominal pain, vomiting, deep or rapid breathing, or confusion, contact your care team or seek urgent care. Additional tests, such as blood glucose, electrolytes, and blood gases, may be used to clarify the cause and guide treatment. If you take an SGLT2 inhibitor and feel ill, ketone testing can be important even when glucose is not very high. Your clinician will advise on next steps, which may include hydration, medication adjustments, and repeat testing to ensure levels are improving.
Reference intervals vary by laboratory, analyzer, methodology, population, and units. The ranges shown here are for education only. Always interpret your results against the reference interval printed on your own lab report.
Fasting, intermittent fasting, ketogenic diets, or very low carbohydrate intake shift your metabolism toward fat use, which raises beta-hydroxybutyrate even when you feel well.
Fever, infections, vomiting, or dehydration increase stress hormones and can reduce effective insulin action, causing ketones to rise more than expected.
Missed insulin doses, pump or infusion set problems, or inadequate sick-day adjustments can raise ketones. Correcting insulin delivery often lowers levels.
Medications such as canagliflozin, dapagliflozin, or empagliflozin can increase the risk of ketoacidosis even when glucose is not very high. Discuss sick-day rules and perioperative plans with your clinician.
Heavy alcohol use combined with poor nutrition can lead to alcoholic ketoacidosis, with elevated beta-hydroxybutyrate despite low or normal glucose.
Endurance exercise can transiently raise ketones as muscles use more fat for fuel. Levels typically fall with rest and carbohydrate refeeding.
Severe nausea and vomiting in pregnancy can increase ketone production. If you are pregnant and unable to keep fluids or food down, contact your clinician.
Results reflect your status at the time of the draw. Proper sample processing and avoiding delays help ensure accuracy when monitoring trends.
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