<prompt> A 30 year old female patient complains of irritability and nervousness. Patient gives history of consumption of oral contraceptives. Lab investigation reveals presence of xanthurenic acid in urine. This patient may be suffering from deficiency of:Vitamin CVitamin B1Vitamin B2Vitamin B6  <response>: Pyridoxine deficiency is associated with neurological symptoms such as depression, irritability, nervousness and mental confusion. Convulsions and peripheral neuropathy are observed in severe deficiency.The synthesis of niacin coenzymes NAD and NADP from tryptophan is impaired. Xanthurenic acid, produced in high quantities is excreted in urine, which serves as a reliable index particularly after tryptophan load test for B6 deficiency.Satyanarayana- Biochemistry, 3rd edition, pg-146 