HCG Test

The HCG test (synonyms: HCG stimulation test; Leydig cell function test) is a procedure that determines the function of Leydig cells. Leydig cells are localized in the testis (interstitial cells of the testis/testicular interstitial cells) and produce the gonadal hormones androstenedione and testosterone.

In this test, HCG (human chorionic gonadotropin) is stimulated to check the endocrine function (testicular secretory reserve) of the testes.

The procedure

Material needed

  • Blood serum

Preparation of the patient/performance

  • Testosterone basal level: fasting two blood draws between 8 and 10 am (at least 30 minutes apart).
  • Followed by 5,000 IU HCG injection i.m.
  • After 48 hours (two blood samples taken at least 30 minutes apart) or
  • After 48 hours and 72 hours further blood sampling (testosterone stimulation value after 48 and 72 h, respectively).

Interfering factors

  • Not known

Standard values

Increase n. HCG administration Interpretation
Physiological Approximately by a factor of 2 (compared with basal level) in males up to 60 years of age
Decreased increase 60 years of age).
High increase > of the 2-fold increase

Indications

  • Leydig cell insufficiency (Leydig cell insufficiency) – To assess testicular secretory reserve.
  • Differentiation between primary and secondary hypogonadism (endocrine dysfunction of the testes leading to testosterone deficiency).
  • Differentiation between anorchia (absent testis) and cryptorchidism (testis is not palpable and has an intra-abdominal location).
  • Intersexuality – due toquestion: occult (hidden) testosterone-producing tissue present?
  • Therapy assessment in maldescensus testis (disturbed testicular descent).

Interpretation

Interpretation of the reduced slope

  • Primary hypogonadism
  • Defect of testosterone biosynthesis.
  • Anorchia
  • Senescence (age)

Interpretation of the high rise

  • Secondary hypogonadism – low levels of gonadotropin (FSH/LH), such as due to pituitary adenoma (neoplasm of the pituitary gland) or hypothalamic tumor.
  • Cryptorchidism
  • Pubertas tarda (delayed puberty)