From the Guidelines
Ketones in urine are primarily caused by the body breaking down fat for energy instead of using glucose, often due to insufficient insulin or impaired insulin function, as seen in uncontrolled diabetes, particularly type 1, and other conditions such as prolonged fasting, high-protein low-carbohydrate diets, and excessive alcohol consumption 1. The presence of ketones in urine, known as ketonuria, can be an indicator of various underlying conditions. According to the guidelines and recommendations for laboratory analysis in the diagnosis and management of diabetes mellitus, individuals prone to ketosis, such as those with type 1 diabetes or a history of diabetic ketoacidosis (DKA), should measure ketones in urine or blood if they experience unexplained hyperglycemia or symptoms of ketosis, such as abdominal pain or nausea 1. Some common causes of ketonuria include:
- Uncontrolled diabetes, particularly type 1
- Prolonged fasting or starvation
- High-protein low-carbohydrate diets
- Excessive alcohol consumption
- Intense physical exercise
- Pregnancy, due to increased energy demands
- Certain medical conditions like fever, vomiting, or diarrhea, which can reduce food intake or cause dehydration It is essential to note that while ketonuria can be a normal finding in certain situations, such as low-carb diets or exercise, persistent ketonuria in diabetic patients requires medical attention, as it may indicate diabetic ketoacidosis, a serious condition 1. Regular monitoring of ketone levels is crucial for diabetic patients, especially during illness or when blood glucose levels are consistently above 240 mg/dL, to prevent and manage diabetic ketoacidosis 1.
From the Research
Causes of Ketones in the Urine
- Ketone bodies are produced by the liver and used during states of low carbohydrate availability, such as fasting or prolonged exercise 2.
- High ketone concentrations can be present with insulin insufficiency and are a key finding in diabetic ketoacidosis (DKA) 2, 3.
- During states of insulin deficiency, lipolysis increases and a flood of circulating free fatty acids is converted in the liver into ketone bodies, mainly beta-hydroxybutyrate and acetoacetate 2.
- As DKA resolves, beta-hydroxybutyrate is oxidized to acetoacetate, which is the predominant ketone in the urine 2.
- Ketones can also be produced in the body under normal conditions, including during pregnancy and the neonatal period, when following a ketogenic diet, fasting, or exercising 4.
- Diet is the main regulator of total body ketone concentrations, and ketogenic diets can mimic the fasting state, altering the default metabolism towards the use of ketones as the primary fuel source 4.
- Other causes of ketones in the urine include diabetic ketosis, alcoholism, and several metabolic disorders 4, 5.
- Metformin overdose can also lead to euglycemic diabetic ketoacidosis (euDKA), a rare but potentially life-threatening condition 6.
- The urine ketone dip test is a highly sensitive screening tool for the detection of ketonemia in patients with DKA and diabetic ketosis 5.