SAT-479 Hyperprolactinemia in a Patient with Multiple Possible Causes

Background: There are many well-identified causes of hyperprolactinemia with prolactinomas and medications being among the most common. In certain cases patients can have multiple possible causes of their hyperprolactinemia making it difficult to identify the exact etiology. This case describes a patient with hyperprolactinemia and three potential causes in whom the suspected etiology was not confirmed until five years after her initial presentation. Clinical Case: A 26-year-old female with a past medical history of tuberous sclerosis and end stage renal disease on peritoneal dialysis presented with a six month history of increasingly irregular menses and bilateral galactorrhea. Menarche was at age ten and she reported menstruating approximately every 30 to 120 days since that time. However since being initiated on peritoneal dialysis her menses had become even more irregular. She denied any vision changes, headache or hirsutism. On examination she was euthyroid with facial acne and bilateral expressible galactorrhea. Her prolactin was found to be mildly elevated at 38.5 ng/mL (n2.8 – 29.2 ng/mL). Her TSH on the same sample was minimally elevated at 4.59 mIU/L (n0.36 – 3.74 mIU/L). Three possible causes of her hyperprolactinemia were postulated. The first was primary hypothyroidism and, while very mild, levothyroxine was initiated. The second was polycystic ovarian syndrome given her history of irregular menses since menarche and her associated acne. The third possible etiology was renal failure, which is a potential cause of hyperprolactinemia irrespective of dialysis modality. No specific treatment for her hyperprolactinemia was given. Clinical Course: Over the following five years her prolactin peaked at 76.9 ng/mL with a corresponding TSH of 7.32 mIU/L. While her TSH fluctuated despite levothyroxine administration, her prolactin remained minimally elevated at 30.4 ng/mL even when her TSH was 2.77 mIU/L. She was placed on medroxyprogesterone for seven days each month resulting in regular menses. She continued to have mild galactorrhea. Five years after starting dialysis she received a kidney transplant and her galactorrhea subsequently resolved. Her prolactin on follow up was 8.4 ng/mL with a normal creatinine, confirming renal failure as the cause of hyperprolactinemia. Conclusion: There are multiple possible causes of hyperprolactinemia and it can sometimes be difficult to determine the exact etiology. While hyperprolactinemia may occur in both PCOS and primary hypothyroidism, it is rarely seen in patients with mildly elevated TSH. Renal failure cannot be confirmed as the cause of hyperprolactinemia until the patient is post transplantation, as in this patient.