Hi! welcome to HCM! Your blood test result shows that your free thyroxine in serum is slightly low. Thyroxine is a hormone made by the thyroid gland in the neck.low thyroxine means hypothyroidism which results when the thyroid gland is unable to make enough thyroxine, TSH hormone is made in the pituitary gland. It is released into the bloodstream. It stimulates the thyroid gland to make thyroxine. If the level of thyroxine in the blood is low, then the pituitary releases more TSH to try to stimulate the thyroid gland to make more thyroxine. Therefore,in hypothyroidism TSH is raised. Now if your thyroxine is low and TSH is also LOW it points towards Central hypothyroidism refering to thyroid hormone deficiency due to a disorder of the pituitary, hypothalamus, or hypothalamic-pituitary portal circulation. Patients with central hypothyroidism frequently have other pituitary hormone deficiencies.Pituitary mass lesions, especially pituitary adenomas, are the most common cause of central hypothyroidism . You can get your TSH repeated and if it comes low again then you can go for tests and scan for piuitary . I sincerely hope this will help you! take care!