Ketones are produced in the liver as a byproduct of fat metabolism. Stored fats are metabolized for the body's energy needs when there is not enough glucose. When glucose is metabolized, it leaves no byproducts. When fats are metabolized, ketones are created as a toxic byproduct. An above-normal amount of ketones in the blood is called ketosis. When ketones are filtered out into the urine, that is called ketonuria.
Ketone bodies are acids that can accumulate in the bloodstream. If enough of these acids build up, that can change the body's pH balance and cause a condition known as metabolic ketoacidosis or diabetic ketoacidosis. People with Type 1 diabetes are prone to this condition. This life-threatening medical emergency is manifested by high blood sugars, frequent urination, constant thirst, constant tiredness and confusion. If left unchecked, it will progress to coma and death. The most telling sign is a fruity breath.
An elevated ketone level could be a warning of impending ketoacidosis. In Type 1 diabetes, the pancreas has stopped producing insulin, which is needed for glucose to be broken down for energy. If glucose can not be used, the body then starts to break down fats to supply the body with energy. It is this breakdown of fats that produces the ketones.
As the network of blood vessels travels through the kidneys, they pass through the nephrons, the functional filtering units of the kidneys. This is where excess water, salts and other wastes are filtered out and form urine, which then is eliminated from the body through the bladder. Between the two kidneys, there are millions of nephrons. Ketones are filtered out in the nephrons. The condition of having ketones in the urine is ketonuria.
High ketone levels are most often an indication of Type 1 diabetes, caused by lack of insulin to break down glucose. Without glucose for energy, the liver begins the breakdown of fats. This produces more ketones than is normal. If the rise in ketones is not caught in time and the body's pH balance is changed, a life-threatening condition known as ketoacidosis has begun.
- "Principles of Anatomy and Physiology"; Gerard J. Tortora, Nicholas P. Anagnostakos; 1990
- Ketones.org: Symptoms of High Ketones