SAT347 Surprising Turn Of Events In A Patient With Weight Gain: Simultaneous Diagnosis Of Macroprolactinoma And Polycystic Ovary Syndrome

Disclosure: A.N. Keskinkilic: None. D. Sistla: None. Background: The differential diagnoses of excess weight gain are broad and endocrinopathies constitute a small proportion of these etiologies. A pattern of associated symptoms, classical exam findings and hormonal testing can signal some endocrine causes. However, diagnosis can still be challenging due to overlapping clinical and biochemical features and concurrent presentations of endocrine disorders. Here, we present a diagnostically challenging rare case of a young female with weight gain who had simultaneous diagnosis of macroprolactinoma and PCOS. Clinical Case: A 34-year-old healthy female presented with one year of weight gain despite lifestyle changes. She also reported headaches, acne, hirsutism, stretch marks, excessive sweating, and had 10 years of amenorrhea while on oral contraceptives (OCs). Labs revealed mildly low free T4 of 0.72 ng/dl (n: 0.70-1.48 ng/dl) and significantly elevated prolactin (PRL) of 259.8 ng/ml (n: 1.2-29.9 ng/ml); normal FSH, LH, GH, IGF, TSH, ACTH, 1 mg dexamethasone suppression test, and 24-hour urinary cortisol. HbA1c, lipid panel, plasma metanephrine and androgen levels were normal. MRI pituitary revealed a 2.1 x 1.9 x 1.5 cm macroadenoma with mild compression to the optic chiasm. A low dose levothyroxine and cabergoline 0.25 mg twice weekly was started with dose increment to 0.5 mg twice weekly. At 6-month follow-up, PRL decreased to 30 ng/ml. Repeat MRI showed a decrease in size of the pituitary adenoma (1.5 x 1.4 x 1.3 cm). However, she could not tolerate cabergoline due to persistent headaches and depression. Hence, she elected to undergo transsphenoidal pituitary resection. Tumor pathology showed sparsely granulated lactotroph adenoma. Post op PRL level normalized, and MRI showed radiological cure of the adenoma. Headaches improved but amenorrhea persisted despite discontinuation of OCs for 6 months. Progesterone challenge tests resulted in withdrawal bleed suggesting anovulation. Repeat work-up ruled out nonclassical CAH, Cushing’s, and androgen-secreting tumors. However, subsequent pelvic ultrasound confirmed polycystic ovarian morphology, suggesting PCOS. The patient preferred to avoid OCs and could not tolerate metformin. She elected progesterone IUD placement for endometrial protection in combination with lifestyle changes with notable improvement in her symptoms. Conclusion: PCOS is a diagnosis of exclusion. Thorough evaluation of symptoms like weight gain, amenorrhea, clinical hyperandrogenism is recommended to rule out serious pathology like prolactinoma. Dual diagnosis of PCOS and macroprolactinoma is rare and should be suspected if menstrual abnormalities persist even after treatment of hyperprolactinemia. Presentation: Saturday, June 17, 2023