Physical Side Effects of Medical Castration
Medical castration with LHRH agonists or antagonists causes multiple physical side effects primarily related to testosterone suppression, including hot flashes, sexual dysfunction (loss of libido and erectile dysfunction), fatigue, metabolic changes (obesity, insulin resistance, lipid abnormalities), increased risk of diabetes and cardiovascular disease, osteoporosis with increased fracture risk, and anemia. 1
Common Physical Side Effects
Sexual and Vasomotor Effects
- Hot flashes - among the most common complaints
- Loss of libido - universal with castrate testosterone levels
- Erectile dysfunction/impotence - occurs in the vast majority of patients
- These effects are directly related to achieving castrate testosterone levels (<50 ng/dL) 2
Metabolic and Cardiovascular Complications
The metabolic side effects increase with duration of continuous ADT and include 1:
- Obesity - weight gain and increased body fat
- Insulin resistance - leading to increased diabetes risk
- Lipid alterations - dyslipidemia patterns
- Increased cardiovascular disease risk - higher rates of cardiac events
- Increased diabetes incidence
Studies show controversial results regarding whether LHRH agonists or surgical castration causes worse metabolic effects, with some suggesting worse lipid profiles after orchiectomy and worse insulin resistance with LHRH agonists 3.
Musculoskeletal Effects
- Osteoporosis - progressive bone density loss
- Increased clinical fracture risk - documented higher fracture rates
- Screening and treatment for osteoporosis should follow established guidelines 1
Hematologic Effects
- Anemia - decreased hemoglobin levels due to testosterone suppression
Physical Function Decline
Quality of life studies demonstrate 2:
- Fatigue - persistent tiredness and reduced energy
- Decreased physical function - reduced strength and endurance
- Urinary problems - though less severe than with other treatments
LHRH Agonist-Specific Considerations
Testosterone Flare
LHRH agonists cause an initial testosterone surge lasting several days before suppression occurs 4. This can cause:
- Disease flare - temporary worsening of symptoms
- Increased bone pain in patients with metastases
- Urinary obstruction in patients with locally advanced disease
Prevention strategy: Administer antiandrogen therapy for at least 7 days before or concurrent with LHRH agonist initiation in patients with overt metastases 2
Local Injection Site Reactions
- Subcutaneous induration/granuloma formation - occurs in 33.5% with leuprorelin and 85.7% with degarelix
- Rubor, dolor, calor (redness, pain, warmth)
- Occasional ulcer or abscess formation
- Large lesions (>3 cm) occur in 1.2% with leuprorelin and 38% with degarelix
- These local reactions do not affect testosterone suppression or clinical outcomes 5
LHRH Antagonist Advantages
LHRH antagonists (like degarelix) offer equivalent testosterone reduction without the initial testosterone surge, eliminating the need for antiandrogen flare protection 4. They achieve:
- Faster castration - 72% castrate by day 8 vs 0% with leuprolide alone 6
- No testosterone flare - 0% vs 82% with leuprolide 6
- Direct LHRH receptor inhibition without initial stimulation
However, antagonists have significantly higher rates of injection site reactions 5.
Important Clinical Caveats
Duration matters: Side effects of continuous ADT increase with treatment duration 1. Intermittent ADT may reduce side effects while maintaining similar survival outcomes, showing modest improvements in physical function, fatigue, hot flashes, libido, and erectile dysfunction compared to continuous therapy 2.
Monitoring requirements: Patients should be counseled about these risks before treatment initiation, and providers should implement screening protocols for osteoporosis, diabetes, and cardiovascular disease 1.
Reversibility: Unlike surgical castration, medical castration is reversible, with testosterone levels normalizing in most patients within 28 days of discontinuation 7. However, recovery may be incomplete or delayed with prolonged use.