hypogonadotropic hypogonadism; gonadotropin deficiency

Introduction

Hypogonadotropic hypogonadism plus pituitary or hypothalamic anatomic lesions & anosmia is known as Kallmann syndrome.

Etiology

• congenital disorders
  • Kallmann syndrome
  • Prader-Willi syndrome
• obstructive sleep apnea
• chronic opioid use
• anorexia nervosa
• idiopathic

Pathology

• selective failure of the neuroendocrine components of the reproductive system in the absence of an anatomic or functional cause
• deficiency of pituitary secretion of gonadotropins FSH & LH resulting from failure to release sufficient gonadotropin-releasing hormone

Genetics

• associated with defects in GNRHR, KISS1R, NELF, FGFR1, CHD7, FGF8

Clinical manifestations

• oligomenorrhea or amenorrhea
• retardation of growth & sexual development
• absence of pubertal development by age 18 years in males
• microphallus &/or cryptorchidism in males
• wide clinical spectrum

Laboratory

• prepubertal sex steroids (serum testosterone, serum estrogen)
• serum FSH, serum LH
  • low or inappropriately normal serum gonadotropin
• serum prolactin to rule out prolactinoma
• urine drug screen for opioids
• karyotyping if suspected congenital disorder

* a history of normal menses rules out hypogonadotropic hypogonadism & further workup not required

Diagnostic procedures

• sleep study (polysomnography) if obese &/or suspected obstructive sleep apena

Radiology

• MRI neuroimaging of pituitary & sella turcica
  • suspected prolactinoma or other pituitary neoplasm

Management

• if associated with weight loss ascribed to change in diet with low BMI, diagnose anorexia nervosa & refer for nutritional & psychiatric consultation

More general terms

• secondary hypogonadism

Database

• OMIM: https://mirror.omim.org/entry/146110
• OMIM: https://mirror.omim.org/entry/614838