Bipolar disorder is a debilitating psychiatric disorder with prevalence of 1-3% in general population. It is a multifactorial disorder which involves environmental, genetic, nutritional and other factors. 5HT widely known as serotonin is synthesized in enterochromaffin cells of intestine, blood platelets and serotonergic neurons of brain. In blood 5HT is stored in platelets. 5HT is an intermediate product of tryptophan metabolism and is a monoamine neurotransmitter in central nervous system. Abnormality in this neurotransmitter is associated with development of bipolar disorder and other psychiatric disorders like depression, anxiety, schizophrenia, mania, aggression. Disturbances in the level of 5HT changes one’s mood. Low level of 5HT is associated with violent behaviour in humans. In the present study plasma 5HT levels were estimated in 38 bipolar disorder individuals and 38 age and sex matched controls without a family history of bipolar disorder. All the patients included in the present study belonged to North Coastal Andhra Pradesh. Student t test was used to compare the 5HT levels in cases and controls. A decrease in the level of plasma 5HT was observed in bipolar cases
