A 67-year-old unemployed, Catholic, right-handed man with a 7-year history of primary hypothyroidism treated with levothyroxine 75 μg and intermediate-risk prostate adenocarcinoma (Gleason 4 + 3 = 7 and ISUP 3), with a low prostate-specific antigen (PSA) of 0.01 ng/dl, rising to 2 ng/dl, and last reported at 4.5 ng/dl with a doubling time of 3 months, was treated with radical prostatectomy and subsequent hormonal blockade (6-monthly application of leuprorelin). Here, KLK3 is linked to Primary hypothyroidism.