Spontaneous Progressive Diminution of Prostate-Specific Antigen Levels as a Clue to Secondary Hypogonadism and Ultimately a Pituitary Macroadenoma

ABSTRACT Objective The objective of this publication is to report a case of secondary hypogonadism in a patient with diminished prostate-specific antigen (PSA) levels who was ultimately diagnosed with a pituitary macroadenoma. Methods The methods used to collect our data include pituitary magnetic resonance imaging and summarization of thyroid and pituitary data, as well as documentation of PSA and testosterone levels. Results A 64-year-old, white male with benign prostatic hyperplasia and prostatic intraepithelial neoplasia was found to have low testosterone levels and decreased sexual drive. The patient showed diminution of PSA levels (from 6.9 ng/dL to <0.05 ng/dL), which led us to suspect low testosterone levels. Further testing revealed progressive decrease in testosterone over a 5-year period to a nadir of <2.5 ng/dL. Additional lab data showed panhypopituitarism, indicating a secondary cause for the hypogonadism. These laboratory findings led to a pituitary magnetic resonance imaging study revealing a solid, cystic macroadenoma occupying the sella turcica and the left cavernous sinus with suprasellar extension. Conclusion A spontaneous decrease in PSA levels indicates a need for further hormonal workup. If low testosterone levels are found concurrently, this may indicate a primary or secondary cause, for which a comprehensive evaluation of the pituitary-hypothalamic-testicular axis is warranted.