Electroconvulsive therapy in a patient with drug-resistant depression and thyroid hormone imbalance

To the Editor

Several studies have shown that thyroid hormones can have an influence on the pharmacological efficacy of antidepressants (Araya et al., 2012). Treatment with antidepressant drugs in patients with coexisting major depressive disorder (MDD) and thyroid hormone imbalance may be ineffective and may cause drug resistance (Dodd et al., 2011). Electroconvulsive therapy (ECT) is therefore recommended in patients with drug-resistant depression (Mathew, 2008; Segi-Nishida, 2011). However, thyroid hormone imbalance can cause a significant delay in commencing ECT. The case history of a patient suffering from MDD and hyperthyroidism confirms this hypothesis. The patient received ECT therapy after pharmacological restoration of thyroid hormone levels that took 18 months.

A 78-year-old patient who had been treated for depression for 15 years was admitted to the psychiatric ward due to non-compliance of antidepressant treatment and a consequent depressive episode with psychosis. At the time of admission the patient had decreased mood, apathy, anhedonia, loss of appetite and weight loss. The patient had suicidal thoughts and delusions. In the past the patient had been treated with radioactive iodine for hyperthyroidism. Laboratory results showed thyroid-stimulating hormone (TSH) 0.0339 uIU/ml, fT4 1.03 ng/dl and fT3 2.12 pg/ml. The diagnosis of hyperthyroidism was made. The endocrinologist prescribed methimazole at a dose of 40 mg/day.

Clomipramine 225 mg/day and olanzapine 5 mg/day were commenced to treat the psychotic depression. Three months later the patient had incomplete remission, so treatment with clomipramine 225 mg/day was maintained, but the patient started taking aripiprazole 15 mg/day instead of olanzapine 5 mg/day. This therapy was ineffective and was discontinued. The patient then received sertraline 100 mg/day and risperidone 5 mg/day; however, the patient’s mental state did not improve and mirtazapine 45 mg/day was added. Despite treatment, the symptoms of severe depression with delusional thoughts about inappropriate digestive tract function, aversion to eating and further weight loss continued. We also observed further life-threatening weight loss despite a high-calorie diet. Apart from hyperthyroidism other diseases were excluded.

The patient maintained compliance of all prescribed drugs (sertraline 100 mg/day, risperidone 5 mg/day, mirtazapine 45 mg/day and methimazole 40 mg/day). Repeat blood tests showed TSH 46.8039 uIU/ml, fT4 1.47 ng/dl and fT3 1.60 pg/ml. On the basis of these results the endocrinologist diagnosed hypothyroidism. Treatment with 25 µg/day of levothyroxinum up to a dose of 150 µg/day was started and after a few weeks euthyroid (normal thyroid function) was obtained. Despite this the patient still had suicidal thoughts, nihilistic delusions and hypochondriacal delusions related to the necrobiosis of his digestive tract. As a result, ECT was commenced. The patient received a course of 12 procedures of ECT under anaesthesia every second day. Simultaneously, the patient received venlafaxine 225 mg/day and olanzapine 10 mg/day.

ECT together with pharmacotherapy was effective. The patient’s mood, appetite and psychomotor drive increased and delusions with suicidal thoughts disappeared. This case report distinctly shows that the coexistence of a somatic disease (thyroid hormone imbalance) might cause a significant delay in the onset of starting ECT in patients with drug-resistant depression. Therefore, it is crucial to obtain euthyroid as soon as possible, otherwise the inability to use ECT and antidepressant drugs can be fatal.