At a glance
Also known as
Why get tested?
To determine the concentration of valproate in the blood and to maintain a therapeutic level
When to get tested?
At regular intervals to monitor the drug’s level; to detect low or excessive (potentially toxic) concentrations
A blood sample drawn from a vein in your arm
Test preparation needed?
What is being tested?
This test measures the amount of valproate in the blood. Valproate is a drug that is used primarily to treat some types of seizure disorders (also called epilepsy), but is also prescribed to treat bipolar disease and to prevent migraine headaches. It may be prescribed in combination with other antiepileptic drugs such as phenytoin or phenobarb to control certain kinds of seizures.
Seizure disorders affect the brain’s ability to transmit electrical impulses and to regulate nerve activity. During a seizure, a patient may experience changes in consciousness, alterations in sight, smell and taste, and may experience convulsions. Seizures are associated with acute conditions, such as high fevers, head trauma, severe infections and exposure to toxins, and with chronic conditions such as metabolic disorders and brain tumours. In many cases the cause is not known. The frequency of seizures varies from a single episode, to occasional seizures, to recurrent. Rarely, a patient may have a seizure that does not stop without prompt medical intervention. People may experience some fatigue and a short period of confusion after a seizure. Muscle contractions during a seizure can lead to an injury and, in some cases, recurrent seizures can eventually lead to progressive brain damage. For most people there will be little or no residual damage.
Bipolar disorder is a mental condition that is characterised by cycles of depression and mania that may last for days, weeks, months, or years. During a depressive episode those affected may feel sad, hopeless, worthless and have thoughts of suicide. During a manic episode, those affected may be euphoric, irritable, use poor judgment and participate in risky behaviours. Valproate is prescribed to help even out the moods of the person with bipolar disorder, especially mania. It is also given to some patients with recurrent migraine headaches, not so much as to treat migraines but to help prevent their occurrence.
Valproate levels must be maintained within a narrow therapeutic range. Too little and the patient may experience a recurrence of symptoms (seizures, mania or migraines); too much and the patient may experience increased side effects. This balance is not always easily achieved. The drug is metabolised by the liver and is processed at a rate that varies from patient to patient and is affected by a patient’s age and the health of their liver. In addition, valproate levels are often affected by other drugs such as carbamazepine, phenytoin, lamotrigine, and phenobarb. They increase the rate of valproate , thus decreasing its concentration in the blood.
Dosages of valproate must be adjusted carefully until a steady concentration in the blood is reached. The actual amount of drug that it takes to reach this steady state will vary from person to person and may change over time.
How is the sample collected for testing?
A blood sample is obtained by inserting a needle into a vein in the arm.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.
How long will I need to be on valproate?
Valproate is usually taken every day (sometimes several times a day) for a patient’s lifetime. An exception to this may be patients whose seizures are caused by a temporary condition; they may only need the medication for a short period of time.
How is valproate taken?
It may be taken as a tablet, slow release tablet, a liquid, or sprinkled on a soft food. It is generally taken with food to minimise stomach upset and it is important that the solid forms be swallowed not chewed to avoid mouth and throat irritation.
Can I test my valproate level at home?
No, it requires specialised equipment. Blood samples are collected from a vein in the arm and tested in the laboratory.