What conditions would a young male be treated for with anastrazole (Aromatase Inhibitor) and growth hormone (GH)?

Anastrozole and Growth Hormone in Young Males

Primary Clinical Indication

A young male would most commonly be taking anastrozole and growth hormone together to maximize adult height potential in the setting of growth hormone deficiency during puberty, where the aromatase inhibitor delays epiphyseal fusion while GH promotes linear growth. 1

Mechanism and Rationale

The combination therapy exploits a critical physiological principle:

• Estrogen, not testosterone, drives epiphyseal growth plate closure in males 2
• Anastrozole blocks aromatase enzyme activity, preventing conversion of testosterone to estradiol 3, 1
• This delays bone age advancement while GH continues to promote linear growth 1
• The strategy extends the window of growth potential before growth plates fuse 2

Specific Clinical Scenarios

Growth Hormone Deficiency with Short Stature

This represents the most evidence-based indication:

• Adolescent males with documented GH deficiency who are in puberty and at risk of compromised adult height 1
• Treatment produces a net gain of +6.7 cm in predicted adult height after 36 months compared to GH alone 1
• Bone age advancement is significantly slower: +2.5 years vs +4.1 years over 3 years (anastrozole vs placebo) 1

Idiopathic Short Stature at End of Puberty

• Boys aged approximately 15 years with testosterone at adult levels but growth velocity <3.5 cm/year 4
• Predicted adult height <2.5 standard deviations below mean 4
• Combined therapy achieved mean adult height of 168.4 cm vs 164.2 cm with GH alone (p<0.02) 4

Chronic Kidney Disease with Growth Failure

• Severely growth-restricted adolescents on long-term dialysis who remain short despite GH treatment 2
• This population is prone to persistent growth failure and may benefit from extended growth potential period 2
• Currently recommended as a research approach rather than standard practice 2

Post-Cushing Disease Remission

• Children in remission from Cushing disease who have GH deficiency and incomplete linear growth 2
• Combined treatment with GH and aromatase inhibitors can reduce bone maturation induced by estradiol in pubertal patients 2
• Often combined with GnRH analogue therapy to delay puberty and maximize catch-up growth 2

Hormonal Effects and Monitoring

Expected Hormonal Changes

• Estradiol decreases by approximately 60% (from ~1.8 to 0.7 pg/mL) 3
• Testosterone increases significantly (117% increase over 12 months) 3, 1
• FSH and LH levels increase due to reduced negative feedback 5
• Normal virilization and pubertal progression continue despite estrogen suppression 3, 1

Critical Monitoring Parameters

• Quarterly height measurements to track growth velocity 6
• Annual bone age radiographs (left wrist) to monitor epiphyseal closure 6
• IGF-1 levels every 6 months to maintain physiologic range and avoid supraphysiological GH dosing 6
• Testicular volume assessment to ensure normal pubertal development 7

Treatment Duration and Stopping Criteria

Treatment should continue until:

• Height velocity drops below 2 cm per year 2
• Epiphyseal growth plate closure is evident on radiography 2
• Patient reaches acceptable final height or near-adult height 2
• Typical treatment duration ranges from 11.5 to 36 months depending on indication 4, 1

Safety Profile

Well-Tolerated Effects

• Body composition, plasma lipids, bone metabolism, and tempo of puberty remain normal 3
• Glucose tolerance and liver function tests unchanged 3, 1
• Most common adverse effects: acne (7%) and headache (7%) 7

Important Caveats

• One patient discontinued due to testicular enlargement 7
• Mean testicular volume increase was +6.6 cm³ with anastrozole vs +5.2 cm³ with placebo 7
• No deleterious effects on virilization or sexual maturation 3, 1

Off-Label and Investigational Uses

Male Subfertility (Different Context)

While not the question's focus, anastrozole alone (without GH) is used in adult hypogonadal men:

• Improves testosterone-to-estradiol ratio in men with BMI ≥25 kg/m² 5
• Increases sperm concentration and total motile count 5
• This is a completely different indication from the pediatric growth promotion use 5

McCune-Albright Syndrome

• Anastrozole was studied in girls with precocious puberty from McCune-Albright Syndrome 7, 8
• Efficacy was not demonstrated in the FDA-reviewed trial 7
• Individual case reports showed some benefit in controlling estrogen excess 8

Common Pitfalls to Avoid

• Never use exogenous testosterone in males desiring future fertility or ongoing growth—it suppresses FSH/LH and can cause azoospermia 9
• Do not assume anastrozole alone will increase height—it requires concurrent GH therapy to promote linear growth 3
• Single height measurements are insufficient—sustained growth velocity over multiple quarters is required to document efficacy 6
• Treatment started too late (after significant epiphyseal closure) will not be effective 2