Summary

Valproate is an anticonvulsant medication that is used primarily to prevent seizures in adults and children and to help even out the moods of someone with bipolar disorder, especially mania. It is also given to some people with recurrent migraine headaches, not so much to treat migraines as to help prevent their occurrence. This test measures the amount of valproate in a sample of your blood. The aim is to achieve the correct level of the drug – enough to prevent symptoms without causing side effects. You may have a test before starting on valproate and then again from time to time especially if there’s been a change in your dose.

Why get tested?

Valproic acid is the generic name of a widely used type of anti-seizure medicine. Valproate is the name of valproic acid after it has changed into the form that works in the body. Several anti-seizure medicines are changed into valproate. 

If your doctor has suggested that you take valproic acid, this test will be used regularly to make sure that the amount of valproate in your blood is at the right level and is stable. Valproate blood levels must stay within a narrow range for the drug to work properly. Too little and there may be a recurrence of your symptoms – seizures, mania or migraines – too much and you may experience side effects.  Your doctor will be particularly concerned about preventing any damage to your liver. This balance is not always easily achieved.

Valproate is processed by the liver and people differ in how quickly their liver metabolises the drug. Your age and the health of your liver will make a difference. Very young and elderly people are more likely to experience increased side effects from the drug. Valproate levels are also often affected by other drugs such as carbamazepine, phenytoin, lamotrigine, and phenobarb. These drugs increase the rate of valproic acid metabolism, and in doing so, decrease its concentration in the blood.
 If your dose seems to be working, regular blood tests can help ensure that valproate levels remain steady. Your dose may need to change over time and the test can be used when adjusting the medication to a more effective dose. 

Having the test

Sample

Blood

Any preparation?

You should talk to your doctor about the timing of sample collection. Since dosage timing varies, and some formulations are time released, collection specifics may vary. Often, the recommended time for sample collection is just before the next dose is taken. This ensures that the minimum amount of drug to be effective is maintained in the blood.

Your results

Reading your test report

Your results will be presented along with those of your other tests on the same form.  You will see separate columns or lines for each of these tests.  

The therapeutic range for valproate has been established at 50 - 120 µg/mL. Within this range, most people will respond without too many side effects. However, response varies with each person. Some people will experience seizures, mood swings or migraines at the low end of the therapeutic range while some people will experience unpleasant side effects at the upper end. For the best outcomes you will need to work closely with your doctor to find the dosage and concentration that works the best for you.

In general, if valproate results are within the therapeutic range, you are not having recurrent seizures, mood swings or migraines, and you are not experiencing significant side effects, then the dosage of valproate you are receiving is considered correct. You should not increase, decrease, or stop taking your medication without consulting your doctor.

A variety of prescribed drugs, over-the-counter medications and supplements can increase, decrease, or interfere with the concentrations of valproate in the blood. You should talk to your doctor about all the drugs and supplements you are taking.

Valproate and pregnancy

Valproate should not be used if you are of childbearing age, and it is possible that you could become pregnant, even if you are not currently planning to have children. Valproate can seriously harm an unborn baby by causing a condition called Fetal Valproate Syndrome (FVS). Babies with FVS are at risk of birth defects and lifelong developmental and learning problems. Some babies are only mildly affected, some may appear to be unaffected, but others may have more serious difficulties. If there is a possibility you could become pregnant and are taking valproate, it is important that you do not stop taking your medication but seek urgent advice from your doctor so they can give you the help and advice you need.

Questions to ask your doctor

The choice of tests your doctor makes will be based on your medical history and symptoms.   It is important that you tell them everything you think might help.

You play a central role in making sure your test results are accurate. Do everything you can to make sure the information you provide is correct and follow instructions closely.

Talk to your doctor about any medications you are taking. Find out if you need to fast or stop any particular foods or supplements. These may affect your results. Ask:

• Why does this test need to be done?
• Do I need to prepare (such as fast or avoid medications) for the sample collection?
• Will an abnormal result mean I need further tests?
• How could it change the course of my care?
• What will happen next, after the test?

Any more to know?

A variety of prescribed drugs, over-the-counter medications and supplements can increase, decrease, or interfere with the concentrations of valproate in the blood. You should talk to your doctor about all the drugs and supplements you are taking.

While severe liver injury is rare, mild increases in liver-related enzymes (AST and ALT) occur in up to 20 per cent of those people taking valproate. These usually return to normal.

Since Valproate increases the risk of neural tube defects such as spina bifida, women of child-bearing age who want to become pregnant should talk to their doctor.

More information