From the Research
Lamotrigine (Lamictal) does not significantly affect serum morning (AM) cortisol levels or interfere with the Dexamethasone suppression test. Based on available clinical evidence, lamotrigine has minimal impact on the hypothalamic-pituitary-adrenal (HPA) axis that regulates cortisol production. Unlike some other anticonvulsants and psychotropic medications that can alter cortisol metabolism or HPA axis function, lamotrigine works primarily through sodium channel modulation and glutamate inhibition, mechanisms that do not directly influence cortisol regulation.
Some studies have investigated factors that can interfere with the dexamethasone suppression test, such as stress, weight loss, and certain medications like diphenylhydantoin, phenobarbital, and carbamazepine 1. However, lamotrigine is not listed among these interfering factors. The dexamethasone suppression test has been evaluated in various contexts, including its use in diagnosing Cushing's syndrome 2, 3, 4, but none of these studies suggest that lamotrigine affects the test's outcome.
Patients taking lamotrigine who require cortisol testing or dexamethasone suppression testing generally do not need to discontinue their medication before these tests, as results should remain reliable. However, it's worth noting that any medication that affects mood or neurological function could theoretically have indirect effects on stress responses, which might subtly influence cortisol levels in some individuals. If precise cortisol measurement is critical for clinical decision-making, discussing the timing of medication and testing with the ordering physician would be prudent.
Key points to consider:
- Lamotrigine's mechanism of action does not directly influence cortisol regulation.
- There is no evidence to suggest that lamotrigine significantly affects serum morning (AM) cortisol levels or the dexamethasone suppression test.
- Certain medications and conditions can interfere with the dexamethasone suppression test, but lamotrigine is not among them.
- Patients on lamotrigine can undergo cortisol testing or dexamethasone suppression testing without needing to discontinue their medication.