What Do High Ammonia Levels in Blood Mean?

High ammonia levels in blood mean ammonia is building up faster than the body removes it. The liver normally turns ammonia into urea, which the kidneys pass out in urine, so liver disease is the most common cause. A high result can also come from kidney disease, rare inherited conditions, or a sample that was not handled correctly.

Ammonia is made when gut bacteria help break down protein. MedlinePlus explains that the test measures the amount of ammonia in a blood sample and that results are read together with symptoms and medical history. This guide helps you understand a result and prepare questions. It cannot tell you the cause of your own result.

MedlinePlus advises calling emergency services or going to an emergency department if someone has symptoms of high ammonia. These include unusual sleepiness, vomiting, confusion, behaviour or mood changes, poor coordination when walking or talking, and seizures. Newborns can show fast breathing or grunting within days of birth.

For people diagnosed with cirrhosis, the NHS says to call emergency services or go to an emergency department if they are vomiting blood, have very dark or black stools, or suddenly become confused or develop slurred speech. MedlinePlus notes that hepatic encephalopathy can get worse quickly and become an emergency. Do not drive yourself; ask someone to take you or call an ambulance.

• New or worsening confusion, forgetfulness or unusual drowsiness
• Slurred speech, shaking hands or arms, or trouble with balance
• Vomiting blood or passing very dark or black stools
• Seizures, or being hard to wake
• Yellow skin or eyes with any of the above

Yes, sometimes. Ammonia is one of the more fragile blood tests. NHS laboratory guidance asks for the sample to go to the laboratory immediately on ice and warns against haemolysis, where red blood cells break open. Red cells contain more ammonia than plasma, so a damaged sample can push the result up.

One NHS pathology service notes that samples arriving after 30 minutes or not kept on ice are still tested, but the report may say the measured result may be higher than the correct result. Laboratories also list some medicines that can interfere with the measurement itself. If a high result does not fit how you feel or your other tests, it is reasonable to ask whether the sample was handled in time and whether a repeat is planned.

• Delay between the blood draw and the laboratory
• Sample not kept cold on the way to the laboratory
• Haemolysis (broken red cells) in the sample
• Smoking or hard exercise before the test, which MedlinePlus says may be avoided beforehand

When the liver is badly damaged, for example by cirrhosis, hepatitis or liver failure, ammonia and other toxins can build up and affect the brain. This is called hepatic encephalopathy. MedlinePlus describes it as loss of brain function caused by the liver being unable to remove toxins from the blood, and notes it is often reversible with prompt treatment.

Early signs can be subtle: changes in sleep pattern, mild confusion or poor concentration, mood or personality changes, a musty or sweet breath odour, or worse handwriting. Later signs include shaking of the hands, slurred speech, disorientation and drowsiness. Family members often notice the change first.

In people with liver disease, episodes can be triggered by infection, bleeding in the stomach or gut, dehydration, constipation, kidney problems, low potassium or sodium, and some medicines, including opioid pain medicines and sedatives. Clinicians look for these triggers as well as the ammonia number.

MedlinePlus lists other conditions linked with higher-than-normal ammonia. Some are common, others rare. The clinician will weigh them against the full picture rather than the number alone.

• Kidney disease or kidney failure
• Bleeding in the upper digestive tract, and a high-protein diet
• Inherited urea cycle disorders, which can show in newborns or later in life
• Reye syndrome, a rare illness mostly in children after a viral infection
• High body temperature, severe muscle exertion and some urinary infections
• Intravenous nutrition and salicylate poisoning

Some can. MedlinePlus lists medicines and substances that may affect ammonia results, including alcohol, acetazolamide, barbiturates, diuretics (water tablets), narcotic or opioid pain medicines and valproic acid. Separately, NHS laboratory guidance notes that a few medicines interfere with the laboratory measurement, which can make a result read falsely high or low.

Do not stop or change any prescribed medicine yourself because of an ammonia result. Talk to the prescriber first. MedlinePlus says a provider may ask you to pause certain medicines before a test, but only after discussion, and some medicines can be harmful to stop suddenly. Bring a full list of prescriptions, over-the-counter products and supplements to the appointment.

Ranges depend on the laboratory, the method and the person's age. MedlinePlus gives one example adult normal range of 15 to 45 µg/dL (10.7 to 32 µmol/L) and notes that ranges vary slightly between labs. Babies and children have different limits. Always compare your result with the reference range printed on your own report.

A single number is only part of the picture. Clinicians consider symptoms, liver and kidney tests, how the sample was collected and whether the level changes on repeat testing. If your liver tests were also abnormal, the guide on raised ALT with a normal liver ultrasound may help with that part of the conversation.

Taking these questions to the appointment can help you understand what the result means for you.

• Was my sample sent on ice and tested quickly, and could handling have raised the result?
• Do you plan to repeat the test, and when?
• Do my liver and kidney tests explain this result?
• Could any of my medicines or supplements be affecting the result?
• Which symptoms mean I should go to the emergency department straight away?
• If I have liver disease, what can trigger confusion, and how can we reduce that risk?

On SameCase, patients and verified doctors share de-identified cases. Reading how others with a similar ammonia result were assessed, which repeat tests they had and what questions they asked can help you prepare for your own appointment. Similar cases cannot diagnose you or replace care from your own team, and in an emergency you should seek urgent help first.