Urine Ketones

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A ketone test checks for ketones in your blood or urine. Ketones are substances that are made when the body breaks down fat for energy. Normally, your body gets the energy it needs from carbohydrate in your diet. But stored fat is broken down and ketones are made if your diet does not contain enough carbohydrate to supply the body with sugar (glucose) for energy or if your body cannot use blood sugar (glucose) properly.

Ketones are the end-product of rapid or excessive fatty-acid breakdown. Examples of ketones are:
·Acetoacetic acid  
·Beta-hydroxybutyric acid  
Ketones will be present in the urine when the ketones in the blood go above a certain level.
A number of hormones, including glucagon, epinephrine, and growth hormone can cause fatty acids to be released from body fat (adipose tissue) into the blood. The levels of these hormones increase in starvation, uncontrolled diabetes, and a number of other conditions.
An insulin deficiency relative to the level of glucagon is also present in persons with diabetes.

When there is carbohydrate deprivation, such as starvation or high protein diets, the body relies increasingly on the metabolism of fats for energy. This pattern is also seen in people with the disorder diabetes mellitus, when a lack of the hormone insulin prevents the body cells from utilizing the large amounts of glucose available in the blood. This happens because insulin is necessary for the transport of glucose from the blood into the body cells. The metabolism of fat proceeds in a series of steps. First, triglycerides are hydrolyzed to fatty acids and glycerol. Second the fatty acids are hydrolyzed into smaller intermediate compounds (acetoacetic acid, betahydroxybutyric acid, and acetone). Thirdly, the intermediate products are utilized in aerobic cellular respiration. When the production of the intermediate products of fatty acid metabolism (collectively known as ketone bodies) exceeds the ability of the body to metabolize these compounds they accumulate in the blood and some end up in the urine (ketonuria).

Ketones (acetone, aceotacetic acid, beta-hydroxybutyric acid) resulting from either diabetic ketosis or some other form of calorie deprivation (starvation), are easily detected using either dipsticks or test tablets containing sodium nitroprusside.

Test results
A negative test result is normal. When ketones are present in the urine, the results are usually listed as small, moderate, or large with these corresponding values:
Small: < 20 mg/dL
Moderate: 30 - 40 mg/dL
Large: > 80 mg/dL
A positive test may indicate:
·Abnormal nutritional conditions  
·High protein or low carbohydrate diets  
·Disorders of increased metabolism  
·Acute or severe illness  
·Nursing a baby (lactation)  
·Postsurgical condition  
·Metabolic abnormalities, including uncontrolled diabetes or glycogen storage disorder  
·Vomiting frequently over a long period of time  

Taking medicines may affect your test result, medicines such as:
·Levodopa, such as Sinemet or Larodopa.  
·Phenazopyridine, such as Pyridium or Uristat.  
·Valproate, such as Depakote, Depacon, or Depakene.  
·Vitamin C (ascorbic acid), when taken in large amounts.  

Also you should know
Special diets can change test results. For example, a diet low in carbohydrates and high in protein and fat can raise ketone levels in the blood, which can then enter the urine.
Some drugs, including glucocorticoids, can cause false positive measurements.

The blood test can check for one type of ketone that the urine test cannot detect. So a urine test that does not show any ketones may not be accurate (false-negative result).
Ketone levels will increase in your urine before they increase in your blood if you are fasting or on a very low-carbohydrate diet.
The American Diabetes Association recommends that you test your urine for ketones if you have diabetes and you:1
·Are pregnant.  
·Are sick or feeling very stressed.  
·Have blood sugar levels of 300 mg/dL (16.7 mmol/L) or higher.  
·Have symptoms of high blood sugar (diabetic ketoacidosis), such as nausea, vomiting, or abdominal pain.  

All information on this page is intended for your general knowledge only and does not provide medical advice, diagnosis or treatment.