Thyroid Science 6(10):CR1-4, 2011 www.ThyroidScience.com Case Reports Primary Hypothyroidism Associated with Hyperprolactinemia and Pituitary Macroadenoma Dragana Jokic, MD and Xiangbing Wang, MD, PhD Division of Endocrinology and Metabolism, Robert Wood Johnson Medical School University of Medicine and Dentistry New Brunswick, New Jersey Corresponding Author: Xiangbing Wang, MD, PhD, FACE Division of Endocrinology, Metabolism & Nutrition Robert Wood Johnson University Hospital-UMDNJ MEB 384B, 1 RWJ Place, P.O. Box 19. New Brunswick, NJ 08903 Phone (732) 235-7751 Fax (732) 235-7069 E-mail: wangx9@umdnj.edu Received: July 13, 2011 Accepted: July 27, 2011 Abstract. Objective: Our purpose is to report a case of primary hypothyroidism associated with hyperpro- lactinemia and pituitary macroadenoma. Background : We present the case report, including detailed lab- oratory and radiological findings in a 28-year-old woman. In primary hypothyroidism there is hyperplasia of both thyrotrophs and lactotrophs as a response to TRH hypersecretion. The hyperplasia can result in sig- nificant enlargement of the pituitary gland and can be mistaken for a prolactin-secreting tumor. Case: We report the case of a female patient who presented with amenorrhea of 7-months duration and was found by her gynecologist to have elevated prolactin. The initial MRI showed a 1.7 cm pituitary mass which was treat- ed initially by cabergoline. Due to the patient’s noncompliance and lack of follow up, the patient remained on cabergoline for 6 months and did not do thyroid function tests. Finally, after 6 months, a follow up MRI showed no change in size of her pituitary mass. Also, blood tests showed profound hypothyroidism, and after 6 month of thyroid replacement therapy, the patient was euthyroid. A repeated MRI of the brain showed complete resolution of the pituitary mass. Result: This case emphasizes the importance of evaluation of thy- roid function in cases of elevated prolactin and gonadal dysfunction. Despite a lack of the typical clinical presentation of hypothyroidism, resolution of the patient’s symptoms and disappearance of her pituitary mac- roadenoma confirms the diagnosis. Conclusion: This case illustrates that primary hypothyroidism can pre- sent with amenorrhea and pituitary mass. Keywords ! Amenorrhea ! Hyperprolactinemia ! Hypothyroidism ! Pituitary macroadenoma ! Prolactin Introduction Prolactin is a pituitary-derived hormone that plays a pivotal role in a variety of reproductive functions. Prolactin negatively modulates the secre- tion of pituitary hormones responsible for gonadal function, including luteinizing hormone and folli- cle-stimulating hormone. An excess of prolactin, or hyperprolactinemia, is a commonly encountered clin- ical condition and is most commonly secreted in ex- cess by pituitary adenoma. The patient usually pre- sents with galactorrhea and gonadal dysfunction. It is important to measure prolactin levels in all patients with unexplained primary or secondary a- menorrhea. This was emphasized in some previous studies that showed that as many as 20% of patients with hyperprolactinemia did not have galactorrhea nor any signs of pituitary dysfunction. Vilar et al. reported on 1234 patients with different etiologies of hyperprolactinemia, as well as the response of 388 patients with prolactinomas to dopamine agonists. [1] Vilar et al. found that 56.2% of patients had pro- lactinomas, 14.5% had drug-induced hyperprolacti- nemia, 9.3% had macroprolactinemia, 6.6% had non- functioning pituitary adenomas, 6.3% had primary hypothyroidism, 3.6% had idiopathic hyperprolacti- nemia, and 3.2% had acromegaly. [1] In men, the diagnosis of prolactin-secreting tu- mors is usually delayed until visual impairment or hypopituitarism appears. The reason is the male’s ini- tial signs of gonadal dysfunction. These signs, de- creased libido and occasionally galactorrhea, are as-