Ketonuria Pathophysiology: Causes, Symptoms & Diagnosis

Ketonuria means there are ketones in your urine. It is also called ketoaciduria or acetonuria. It can be a sign of diabetic ketoacidosis, fasting or starvation, a very low-carb diet, or other medical conditions.

Your liver makes ketones when your body breaks down fat for fuel instead of glucose. Small amounts are a normal response to fasting, but high levels can be dangerous, especially in people with diabetes.

Ketonuria is a key warning sign in diabetes mellitus, especially type 1 diabetes mellitus. It can also occur during pregnancy with prolonged vomiting, or in breastfeeding women who aren't eating and drinking enough.

During fasting or starvation, your cells don't get enough glucose from food. Your body then breaks down stored fat for energy, and ketones are made as a byproduct. That's why starvation can cause ketonuria.

What Are The Causes Of Ketonuria Or Ketoaciduria?

Many medical conditions can cause ketonuria. The most common causes are below.

1- Diabetes Mellitus/ Low Insulin Level

Most of your body's energy comes from glucose. This glucose comes mainly from the carbohydrates you eat. After a meal, carbohydrates are broken down into glucose, and your blood sugar rises.

To bring blood sugar down after a meal, your body releases a hormone called INSULIN.

Insulin is made by the beta cells of the pancreas in response to rising blood glucose. It signals cells in your muscles, liver and fat tissue to take in glucose and use it or store it.

When insulin is too low, the body can't use glucose as fuel, even though blood sugar is high. It then breaks down fat for energy, producing ketones as a byproduct.

If insulin deficiency continues, ketones build up in the bloodstream and make the blood acidic. This is called diabetic ketoacidosis (DKA). It is a medical emergency that can harm your organs and be life-threatening.

As ketones build up in your blood, your kidneys remove some of them through urine. That's why ketonuria is an early sign of ketoacidosis in people with diabetes. People with diabetes who check for ketones can catch DKA before it becomes severe.

2- OTHERS

MedlinePlus lists other causes of high urine ketones, including:

Fasting or starvation, such as with anorexia
Low-carbohydrate or ketogenic diets
Prolonged vomiting, such as during early pregnancy
Breastfeeding without enough food and fluids
Severe illness, such as sepsis, burns or high fever
Hyperthyroidism
SGLT-2 inhibitor diabetes medicines, which can cause ketones even when blood sugar isn't very high

Heavy alcohol use can also cause a dangerous buildup of ketones called alcoholic ketoacidosis.

Signs & Symptoms Associated With the Ketonuria

Mild ketonuria from fasting or a low-carb diet often causes no symptoms. When ketones build up because of DKA, the symptoms can become serious. The more ketones in the blood, the more severe the illness.

Symptoms of DKA may include:

Fruity-smelling breath
Deep, rapid breathing
Thirst
Dry mouth and skin
Dehydration
Nausea or vomiting
Abdominal pain
Frequent urination
Fatigue
Confusion or decreased alertness
Headache and muscle aches

On lab tests, your doctor may find:

High ketone levels in urine and blood
High blood sugar
Acidic blood
Electrolyte imbalance

How Ketonuria Can Be Diagnosed?

Diagnosis starts with:

A medical history
A physical exam
A urine test

A urine ketone test can be done with an at-home dipstick or a lab sample. A negative result is normal. Positive results are usually reported as small, moderate or large.

If urine ketones are found in someone with diabetes, doctors may also order:

A blood ketone test (beta-hydroxybutyrate)
Arterial or venous blood gas to check acidity
A basic metabolic panel for electrolytes and kidney function
Blood glucose tests, repeated often during treatment
Tests for infection, such as blood cultures or a chest X-ray, if an illness may have triggered DKA

Complete Management of Ketonuria

Treatment of ketonuria depends on the cause.

1. Ketonuria Due to starvation

If ketones are due to fasting or not eating enough, they usually clear once you eat regularly again. Severe or prolonged starvation still needs medical care.

2. Ketonuria Due to Diabetes

If you have diabetes and your ketones are moderate or large, contact your healthcare provider right away. DKA usually needs hospital treatment, which includes:

Insulin, usually given through a vein
Intravenous (IV) fluids to treat dehydration
Replacement of electrolytes such as potassium, guided by blood tests

Doctors may add glucose to the IV fluids as blood sugar comes down, so insulin can keep clearing ketones safely.

3. Ketonuria Due to Illness

If an illness such as an infection triggered DKA, doctors also treat that cause, for example with antibiotics for a bacterial infection.

During treatment, the care team checks blood glucose often, along with electrolytes and urine output. Patients can be critically ill at this stage, so fluids, electrolytes and blood glucose are all carefully managed.

Complications

If DKA is not treated, it can cause serious, life-threatening complications such as:

Cerebral edema (brain swelling), especially in children
Dangerously low potassium
Cardiac arrhythmias and cardiac arrest
Severe dehydration
Kidney failure
Coma and death

An altered state of consciousness is a warning sign.

People with diabetes should know the signs of DKA. If you have fruity-smelling breath, vomiting, deep breathing or confusion, seek emergency care right away.

HP Thoughts: Kidneys play an important function in your body since this body part manages the proper filtration of waste materials. Once its role fails, then the entire body suffers considerably. One of the worst-case scenarios would be this: Acute Renal Failure.