Catecholamines are neurotransmitters. They include dopamine, norepinephrine, and epinephrine. These proteins help transmit signals in your body and brain. They help control a variety of functions, including:
- muscle tone
- heart rate
- blood pressure
- glucose (sugar) metabolism
Catecholamines are primarily produced in your adrenal glands. Levels fluctuate in response to physical and emotional stress. They can also change in response to:
- outside temperature
- blood loss
- low blood sugar
- going from seated to standing, or vice versa
Catecholamine urine testing (CATU) is usually only used if you have symptoms of certain diseases that increase production. Because levels are so variable, testing is not generally recommended for people without symptoms. The chance of a false positive test is too high.
A doctor usually orders a CATU to look for signs of a pheochromocytoma. This is a type of tumor that usually grows on your adrenal glands. It makes catecholamines.
In children, a CATU may be ordered if a doctor suspects the presence of a neuroblastoma. This is an aggressive nervous system tumor. Often starting in the adrenal glands, a neuroblastoma can increase catecholamine levels.
The sooner a child is diagnosed with a neuroblastoma, the better his or her chances of survival. According to the Ped-Onc Resource Center, 90 percent of children under the age of 1 who are diagnosed with neuroblastoma will survive (Ped-Onc , 2011).
The symptoms of a pheochromocytoma are:
- high blood pressure
- rapid heartbeat
- unusually hard heartbeat
- heavy sweating
- weight loss
- severe headaches off and on for an extended period
- pale skin
- unexplained weight loss
- strong, unexplained anxiety
It is important to note that these symptoms do not always indicate a pheochromocytoma. They can have many other causes.
The symptoms of neuroblastoma include:
A CATU measures the amount of catecholamines in your urine. It is usually performed over a period of 24 hours. Levels fluctuate greatly during the day.
The Mayo Medical Laboratories list normal levels as:
<1 year: 0.0 to 2.5 mcg/24 hours
1 year: 0.0 to 3.5 mcg/24 hours
2 to 3 years: 0.0 to 6.0 mcg/24 hours
4 to 9 years: 0.2 to 10.0 mcg/24 hours
10 to 15 years: 0.5 to 20.0 mcg/24 hours
> or =16 years: 0.0 to 20.0 mcg/24 hours
<1 year: 0 to 10 mcg/24 hours
1 year: 1 to 17 mcg/24 hours
2 to 3 years: 4 to 29 mcg/24 hours
4 to 6 years: 8 to 45 mcg/24 hours
7 to 9 years: 13 to 65 mcg/24 hours
> or =10 years: 15 to 80 mcg/24 hours
<1 year: 0 to 85 mcg/24 hours
1 year: 10 to 140 mcg/24 hours
2 to 3 years: 40 to 260 mcg/24 hours
> or =4 years: 65 to 400 mcg/24 hours
(Mayo Medical Laboratories , 2012)
High levels of catecholamines may indicate:
- paraganglioma - a rare nervous system tumor
A CATU alone cannot diagnose disease. Further tests will be needed if you have high levels. These may include imaging tests to look for tumors. There is a high probability of a false positive test if you do not have symptoms.
Preparation is usually not needed for this test. However, several common products can interfere with catecholamine levels. These include:
- allergy medicines
Your doctor will probably give you a list of what to avoid before your test. Make sure to tell your doctor all the medicines you are taking. Include both prescription and over-the-counter drugs.
If your child is scheduled for a CATU, and you breastfeed, talk to your doctor. Catecholamines pass from mother to child through breast milk. You may also have to watch your food and medication intake.
A CATU may take place in your home. It can also be performed at your doctor’s office. In either case, a “clean-catch” urine sample is required.
You will be given a sterile container and a disposable, sterile wipe. Use the sterile wipe to clean the urinary opening. Women should gently wipe from front to back. Men should gently wipe the head of the penis.
Begin to urinate into the toilet and stop. Place the open, sterile container in a position to catch the stream of urine. Fill the urine container almost to the top and stop.
Move the container out of the way and finish urinating into the toilet. Place the top on the container. Deliver the container to your doctor.
This technique can also be used to collect urine from older children. To collect urine from an infant or young child, you will use a pediatric urine bag. This bag is placed inside the diaper to collect urine. It will come with detailed instructions.
Sometimes a catheter will be used to collect urine from children. This involves placing a small tube into the urinary opening. It can cause temporary discomfort. However, it may be necessary to get accurate CATU results.
Your test results should be ready in a couple of days. Your doctor will discuss them with you when they are available.
A CATU is usually accurate in diagnosing pheochromocytoma and neuroblastoma. However, further testing is needed to determine the size and location of tumors. In general, both conditions are highly treatable.