T1 L19 Endocrine aspects of male hypogonadism Flashcards
What is testosterone?
Steroid hormone secreted by testes, ovaries and adrenals
How much testosterone do young men produce per day?
7mg
<5% is from adrenal secretion
Describe the distribution of testosterone in the blood
2% is present as free hormone
≥50% is bound to albumin
44% is bound to sex-hormone-binding globulin
What are the 2 parts of the testes?
Seminiferous tubules
Interstitium
Describe the seminiferous tubules in the testes?
Sertoli cells synthesis inhibin B and anti-mullerian hormones
Sperm are produced here
Describe the interstitium of the testes
Contains Leydig cells which produce androgens
Contain peritubular myoid cells
What is the role of LH in males?
Release of testosterone
What is the role of FSH in males?
Involved in spermatogenesis and inhibin B secretion
What is the mechanism of action of testosterone?
Penetrates target cells to stimulate growth and function of the cells
Androgen target cells convert testosterone to 5-a-dihydrotestosterone before it binds to androgen receptor
Testosterones can be aromatised to oestrogens
What is the role of testosterone?
Regulation of gonadotrophin secretion by hypothalamic-pituitary system
Initiation & maintenance of spermatogenesis
Formation of male phenotype during embryogenesis
What is male hypogonadism?
Decrease in one or both of the 2 main functions of the testes
- sperm production
- testosterone production
Describe primary hypogonadism
Disease of the testes
Testosterone below normal
Serum LH and/or FSH above normal
Describe secondary hypogonadism
Disease of hypothalamus or pituitary
Testosterone below normal
Serum LH and/or FSH normal or low
What are the causes of primary hypogonadism?
Klinefelter syndrome Cryptorchidism Infection Radiation Trauma Torsion Idiopathic
What are the causes of secondary hypogonadism?
Congenital GnRH deficiency Hyperprolactinaemia GnRH analogue Androgen Opioids Illness Anorexia nervosa Pituitary disorder
What are the symptoms and signs of male hypogonadism?
Incomplete sexual development Decreased sexual desire, activity and spontaneous erections Decreased body hair Decreased muscle bulk and strength Decreased mood, energy, motivation, aggression Breast discomfort, gynaecomastia Very small or shrinking testes Low sperm counts Hot flushes / sweats Sleep disturbance Mild anaemia
What conditions have a high prevalence of hypogonadism?
Sellar mass, radiation to sella or other sellar diseases Medications affecting testosterone production or metabolism e.g. glucocorticoids, ketoclonazole, opioids HIV-associated weight loss ESRD and maintenance haemodialysis Moderate to severe COPD Osteoporosis or low trauma frature Type 2 diabetes mellitus Infertility
What medical history is relevant in hypogonadism?
Puberty and sexual development Past / present major illness Past / present nutritional deficiency Drug history Relationship problems Sexual problems Major life events Related family history Recent changes in body Testicle problems
What should be examined in male hypogonadism?
Amount of body hair Breast exam for enlargement and tenderness Size and consistency of testicles Size of penis Signs of severe and prolonged hypogonadism -loss of body hair -reduced muscle bulk and strength -osteoporosis -smaller testicles Arm span
What investigations should be done in male hypogonadism?
Serum testosterone LH / FSH SHBG LFT Semen analysis Karyotyping Pituitary function testing MRI DEXA scan
What can decrease SHBG?
Moderate obesity
Nephrotic syndrome
Hypothyroidism
Use of glucocorticoids, progestins and androgenic steroids
What can increase SHBG?
Ageing Hepatic cirrhosis Hyperthyroidism Anticonvulsants Oestrogens HIV infection
What is the treatment for male hypogonadism?
Testosterone in form of gel, injection, buccal, patch or pellet
What monitoring should be done during testosterone treatment for hypogonadism?
Testosterone PSA FBC DRE DEXA
What contraindications are there to testosterone therapy?
Breast or prostate cancer Lump / hardness on prostate exam by DRE PSA >3ng/ml that hasn't been evaluated for prostate cancer Severe untreated BPH Erythrocytosis Hyperviscosity Untreated obstructed sleep apnoea Severe heart failure (class III or IV)
What is gynaecomastia?
Benign proliferation of glandular tissue of male breast
Diagnosed on exam as palpable mass of tissue above 5cm diameter
What are the causes of gynaecomastia?
Persistent pubertal gynaecomastia Drugs Idiopathic Cirrhosis or malnutrition Hypogonadism Testicular tumour Hyperthyroidism Chronic renal insufficiency
What information is needed in a history for gynaecomastia?
Duration Breast pain / tenderness Systemic disease Weight gain or loss Use of medication / recreational drugs Exposure to chemicals Fertility Sexual function Family history
What examination should be done for gynaecomastia?
Virilisation Testicular size Penis Sign of CLD or CRF Thyroid Breast
What investigations should be done for gynaecomastia?
Testosterone LH / FSH Prolactin LFT / U&E B-hCG TFT Oestrogen U/S
What is the treatment for gynaecomastia?
Conservative - reassurance
Treatment of cause
Tamoxifen
Surgery
