For galactorrhea and amenorrhea syndromes, what is the investigation in addition to serum prolactin?

In patients with Iodine deficiency Low T4/T3 results in TSH || by Feedback mechanism & to ||TSH the TRH is also elevated(||) Now this ||TRH will increase both TSH and Prolactin production. Therefore Hyperprolactinemia resulting in Galactorrhea can also be seen in Patients with thyroid malfunction.