SAT-180 Absence of Diurnal Variation in Serum Testosterone Levels in Patients receiving Clomiphene Citrate for Male Hypogonadism

Abstract Disclosure: M.K. Shakir: None. H. Babu: None. N.O. Vietor: None. A.J. Spiro: None. T.D. Hoang: None. Background: Clomiphene Citrate (CC), a selective estrogen receptor modulator, is widely used for treating male hypogonadism. Although serum testosterone (T) levels show a diurnal variation, it is not clear whether patients receiving CC demonstrate such diurnal variation. The diurnal variation of serum T was analyzed in 3 CC-treated patients with secondary hypogonadism. Methods: The serum T was drawn at 7AM while fasting, 11AM before lunch, and 4PM before dinner. T levels were assayed by LC/MS LabCorp TM. Case 1. A 48-year-old man presented with symptoms of hypogonadism. Lab Results: Serum T 148 ng/dL, FSH 4.8 mlU/mL, LH 9.2 mIUL, prolactin 9.6 ng/mL and IGF-1 168 ng/mL. Pituitary MRI revealed a 4 mm pituitary tumor (non-functioning). After counseling, patient was placed on CC 25 mg every other day. Patient noted improvement in hypogonadism symptoms and pituitary MRI remained stable. T levels performed 12 months later showed the following values: T: 7 AM 438 ng/dL; 11AM 399 ng/dL; and 4 PM 378 ng/dL. Case 2. A 38-year-old man presented with symptoms of hypogonadism. Laboratory values: Serum T 154 ng/dL, FSH 4.9 mIU/mL. LH 5.8 mIU/mL, prolactin 9.8 ng/mL, IGF-1 198 ng/mL. Pituitary MRI was normal. He was treated with CC 25 mg every other day. Six months later, T level showed the following values: T 7 AM 326 ng/dL; 11 AM 411 ng/dL; and 4 PM 458 ng/dL. He also had significant improvement in symptoms. Case 3. A 52-year-old man was seen for evaluation of erectile dysfunction and secondary hypogonadism. Laboratory values: Serum T 138 ng/dL, FSH 3.0 mIU/mL, LH 7.1 mIU/mL, prolactin 11.8 ng/mL, IGF-1 138 ng/mL. Pituitary MRI was normal. Patient was treated with CC 50 mg every other day and 9 months later T values were: T 7 AM 478 ng/dL; 11AM 412 ng/dL and 4 pm 398 ng/dL. He noted significant improvement in hypogonadal symptoms. Conclusion: In this case series the serum T levels did not show any diurnal variation. The exact significance of a steady state serum T levels during daytime is not clear. Further studies involving a large number of patients are needed. Presentation: Saturday, July 12, 2025