Lab test
Ammonia Test – Ammonia Levels Liver Test
Ammonia Test – Ammonia Levels Liver Test can be ordered without a referral from your own doctor, and this guide covers what to expect. An ammonia test measures the amount of ammonia in the blood. It is often used to check liver function and investigate symptoms like confusion or fatigue.
Lab requirements in Ammonia Test – Ammonia Levels Liver Test
Here is what you need before ordering and completing the Ammonia Test – Ammonia Levels Liver Test. Review each item and confirm the details with the collection lab.
- Physician's order
- Included. A physician's order is required for lab testing and is provided for you by our partner's physicians — no referral from your own doctor is needed.
- Fasting
- Fasting is required for this test — follow the collection lab's instructions.
- Preparation
- Your collection lab will give you specific instructions, which may include fasting for a period of time before the test. Always follow the lab's instructions exactly.
- Sample & visit
- A blood and/or urine sample is collected; the visit usually takes about 10 minutes.
- Identification
- Bring the lab requisition form from your account. The collection lab may also ask for a government-issued photo ID.
- Turnaround
- 1-3 business days
- Availability
- Our partner lab does not serve ND, RI, NY, NJ, MD or HI. Confirm availability for your location with the collection lab.
Before you go
- Order your test before visiting a lab, then use the requisition form in your account.
- Print the requisition form, or fax it to the lab directly from your account.
- No scheduling is needed — visit the collection lab during its normal business hours.
- A blood and/or urine sample is collected; the visit usually takes about 10 minutes.
- Bring a government-issued photo ID in case the lab requests it.
- Results are posted to your secure account within 1–3 business days.
Requirements are summarized from our partner lab's published policies. Preparation and availability can change — confirm current instructions with the collection lab before your visit.
What this test is
Ammonia is a waste product made when the body breaks down protein. A healthy liver normally converts ammonia into urea, which is removed in urine. When the liver is not working properly, ammonia can build up in the blood.
What it measures
- Ammonia — reflects how well the liver is clearing this waste product from the blood
- Blood urea nitrogen (BUN) — often measured alongside ammonia to assess liver and kidney function
- Liver enzymes (ALT, AST) — may be included to check for liver cell damage
What the test involves
The test requires a standard blood draw from a vein, usually in your arm. In some cases, a urine sample may be collected instead or as well.
Why it is often ordered
A clinician may order an ammonia test if you have symptoms such as ongoing tiredness, confusion, or mental fogginess, especially if you have a known liver condition. It can also be used to monitor people with liver disease or certain metabolic disorders.
Preparation
Your collection lab will give you specific instructions, which may include fasting for a period of time before the test. Always follow the lab's instructions exactly.
How results are reported
Results are usually reported as a number that your clinician will interpret. Reference ranges vary by laboratory, so your result should always be compared to the range provided by the lab that performed the test.
Before you go
- Whether you need to fast before the test and for how long
- Any medications or supplements you should avoid before collection
- When and how you will receive your results
FAQ
Frequently asked questions
Do I need to fast for an ammonia test?
Some labs ask you to fast for several hours before the test, while others do not. The collection lab will provide specific instructions. Always follow those instructions to help ensure accurate results.
What can cause high ammonia levels?
High ammonia levels can occur with liver disease, certain inherited metabolic disorders, or severe gastrointestinal bleeding. Some medications and other conditions may also affect levels. Only a clinician can interpret what your result means for you.
How long does it take to get ammonia test results?
Results are typically available within one to three business days, but this can vary by laboratory and how the sample is processed. Your ordering clinician will receive and explain the results.
Can I eat or drink before the test?
Unless the lab tells you otherwise, you may be able to eat and drink normally. However, some labs require fasting. Check with your collection lab for the exact preparation needed.
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