Male hypogonadism (reduced testosterone secretion) – Tests to diagnose

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Article by Doctor Trinh Ngoc Anh - Endocrinologist - Department of General Internal Medicine - Vinmec Times City International General Hospital.

1. Outline

Male hypogonadism is a clinical syndrome characterized by testosterone deficiency and adversely affects multiple organ function and quality of life.

2. Tests needed to make a diagnosis

Hypogonadism can result from any degree of hypothalamic-pituitary-gonadal axis damage. Tests to confirm and diagnose the cause will depend on the extent and location of the lesion.
2.1 Tests for serum testosterone levels Hypogonadism is diagnosed on the basis of frequently occurring symptoms and signs associated with androgen depletion and against low testosterone levels (on at least 2 occasions). measure) by a reliable method. The threshold for diagnostic Testosterone testing according to the European Society of Urology:
Low Total Testosterone (tT): (<12.1 nmol/L) Low Free Testosterone (fT): (<243 pmol/L)

However, hypogonadism may not always be obvious and is not always characterized by low testosterone levels that should be correlated with age and clinical symptoms. A man with low total testosterone <300ng/dl (10 nmol/l) is more likely to have hypogonadism. Testosterone levels between 200-400ng/dl (7-13 nmol/l) should be retested along with free testosterone levels. Fluctuations in testosterone levels with diurnal rhythms should also be considered when evaluating results. As men reach adulthood, this cyclical fluctuation also disappears; Therefore, in the elderly, the time of testing is no longer important. Measurement of free testosterone should be indicated if abnormal SHBG blood levels are suspected.
2.2 FSH and LH tests Normal in adult men: FSH 1.27 – 19.26 mUI/ml (1.27 – 19.26 UI/l), LH 6 – 23 mUI/ml (6 – 23 Arb unit); boys without puberty FSH 0.5 – 3.7 mUI/ml (0.5 – 3.7 UI/l), LH 6 – 19 mUI/ml (6 – 19 Arb units). Decreased testosterone accompanied by elevated FSH and LH is seen in primary hypogonadism while decreased testosterone accompanied by decreased or normal FSH and LH is seen in secondary hypogonadism. 2.3 Stimulation test with HCG Indications: + Children with sex organs of unknown sex, palpable.
+ Male children with delayed puberty or suspected undescended testicles.
+ Assess the presence of active testicular tissue.
How to do: + Day 0: take blood test for testosterone, androstenedione and dihydrotestosterone.
+ Days 1, 2, 3: IM every morning 1500 UI HCG (Pregnyl ampule 1500 UI), the dose of injection may vary depending on the age and weight of the child.
+ Day 4: draw blood in the morning (24 hours after the last injection) to measure testosterone, androstenedione and dihydrotestosterone.
+ Some documents record how to inject 5000UI once in men who have gone through puberty.
Results: normal testosterone after injection increased at least 150 ng/dl (~5.0 nmol/l), testosterone increased gradually after injection but the highest increase was 72 hours after injection. Assessing the ratio of Testosterone/Androsterinone, if <0.8, it is highly suggestive of 17-β-hydroxysteroid dehydrogenase deficiency. Some studies have suggested that estradiol (E2) can be quantified instead of testosterone and that 24-h post-injection can also help assess Leydig cell function.

2.4 GnRH stimulation test Gonadoreline drug vial 100mcg powder for injection
Intravenous or subcutaneous injection 100mcg GnRH, venous blood is drawn at 15, 30, 45, 60 and 120 minutes for LH&FSH quantification, average results Usually, LH levels increase 3-6 times after 30-45 minutes and FSH increases 20-50%
Primary hypogonadism, FSH and LH elevation, even beyond normal
Hypothalamic or glandular failure At rest, FSH and LH do not increase or increase little, sometimes can increase near normal
*Stimulation test with Clomiphene
Oral 100mg clomiphene citrate for 5-7 days
Blood collection after the end of the course, in people with hypothalamic-pituitary function normal LH doubled and FSH increased 20-50% compared to pre-test
*Other tests:
Sperm analysis is the best way to assess sperm count and Usually indicated for adult men wishing to insemination. The test should be done after 2-3 days of not having sex and should be tested within 2 hours of collecting the sperm sample. Sperm will be analyzed for number, shape, and motility. Under normal circumstances, sperm count would be >20 x 106/ml, >50% have good motility, and >30% have normal morphology (this is the lower limit that allows patients with low sperm count). artificial insemination). Abnormal values ​​may be encountered in patients with recent fever, trauma, or use of drugs that cause transient damage to spermatogenesis. A below-normal decrease in sperm count, normal testosterone levels with mildly elevated FSH levels, and normal LH suggest damage to the seminiferous tubules while Leydig cells function normally. In cases of suspected secondary hypogonadism, additional prolactin, thyroid-stimulating hormone (TSH), free T4, serum cortisol (8 am blood collection or adrenocortical stimulation test) should be performed, iron , Ferritin for further investigation of pituitary causes MRI should be indicated if testosterone and LH levels are low while serum prolactin is elevated. If other pituitary hormone levels are abnormal or if visual field disturbances or neurologic findings are present, an MRI of the pituitary gland should be performed to rule out lesions in this area. If there is a contraindication to MRI, cranial CT with or without contrast should be indicated, although the image quality will be poor. Primary hypothyroidism can cause hyperprolactinemia and hypogonadism (due to an increase in TRH levels).

Tests to diagnose male hypogonadism are quite diverse, sometimes it is necessary to do many times to compare and draw conclusions. Therefore, men with symptoms of hypogonadism should be examined with a specialist in Orrology or Endocrinology for advice and determination of appropriate tests for their disease status.
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>> See more: Male hypogonadism (reduced testosterone secretion) - A disease that is often forgotten - Written by resident doctor Trinh Ngoc Anh - Department of Internal Medicine - Vinmec Times City International Hospital

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