Author(s): L. Vishalakshi, M. G. Hemapriya
Lithium is a novel mood stabilizer in the treatment of bipolar disorders. Toxic effects are frequently encountered in clinical practice due to its narrow therapeutic index. Thyrostatic effects especially clinical hypothyroidism, is a well-known side effect of long term lithium treatment and has been reported in medical literature. However, Indian studies on this major issue is sparse.
The aim of the study was to evaluate the prevalence and risk factors for the onset of hypothyroidism (overt and subclinical) in bipolar disorder patients treated with lithium.
MATERIALS AND METHODS
110 patients who fulfilled the study criteria were taken from inpatient and outpatient departments of Institute of Mental Health and assessed for prevalence of hypothyroidism (clinical and subclinical) based on thyroid function test taken from case records (T3, T4, TSH). Retrospective analysis of risk factors like age, sex, weight gain during lithium intake, family history of thyroid disease, dose and duration of lithium intake and onset of hypothyroidism was done.
In our study, the prevalence of overt and subclinical hypothyroidism in bipolar patients treated with lithium was 32.7% and 15.5% respectively. Strong association was present between the risk factors (female sex, age group of 51-60 years of age, positive family history, and weight gain during lithium intake) and onset of overt hypothyroidism. Subclinical hypothyroidism developed within 1-3 yrs. at a dose of 900mg of lithium per day and overt hypothyroidism took >3 yrs. to manifest at a dose of 1200mg of lithium after the start of treatment.
Hypothyroidism in bipolar patients worsens the mood symptoms, leads to cognitive impairment and alters the response to psychotropic drugs. It calls for a mandatory drug review, along with baseline and periodic thyroid function test especially in high risk cases. Early intervention with thyroxin supplementation improves the patient mood and wellbeing.