Thyroid Disorders and Hirsutism in Postmenopausal Women
Thyroid disorders play a minimal and indirect role in hirsutism development in postmenopausal women, and should not be considered a primary cause of excess hair growth. While thyroid dysfunction is common in this population, it is not a direct driver of hirsutism pathophysiology.
Primary Causes of Hirsutism in Postmenopausal Women
The overwhelming majority of hirsutism cases in postmenopausal women stem from androgen excess, not thyroid dysfunction. The most common etiologies include 1:
- Polycystic ovary syndrome (PCOS) - accounts for 70-80% of androgen excess cases 1
- Idiopathic hirsutism - present in 5-15% of hirsute women with normal ovulatory function and androgen levels 1
- 21-hydroxylase-deficient nonclassic adrenal hyperplasia 1
- Androgen-secreting tumors (ovarian or adrenal) 1
- Iatrogenic causes from androgenic medications 2
Thyroid Dysfunction as a Secondary Consideration
Thyroid disorders should be evaluated as part of the comprehensive workup for hirsutism, but they are not causative agents. The relationship is indirect 2:
Why Thyroid Testing Matters
- Thyroid dysfunction is highly prevalent in postmenopausal women - affecting approximately 23.2% with subclinical disease and 2.4% with clinical disease 3
- Symptoms of thyroid disease can mimic or coexist with other endocrine abnormalities that do cause hirsutism 3
- Both hypothyroidism and hyperthyroidism are listed among potential etiologies requiring exclusion during hirsutism evaluation 2
The Diagnostic Algorithm
When evaluating hirsutism in a postmenopausal woman, thyroid function testing serves to exclude concurrent endocrinopathy, not to identify the primary cause 1, 2:
- Confirm true hirsutism - presence of terminal (coarse) hairs in male-pattern distribution 1
- Measure total and free testosterone to detect androgen excess 1
- Check DHEA-S to evaluate adrenal androgen production 1
- Obtain TSH to exclude thyroid dysfunction as a confounding factor 1, 2
- Consider 17-hydroxyprogesterone if adrenal hyperplasia suspected 1
Clinical Context in Postmenopausal Women
The Canadian Task Force recommends maintaining high clinical suspicion for thyroid dysfunction when examining perimenopausal and postmenopausal women 4. However, this recommendation relates to the general prevalence of thyroid disease in this population, not specifically to hirsutism causation.
Postmenopausal women with subclinical hypothyroidism (TSH >10 mU/L) should be treated 5, and symptomatic women with TSH <10 mU/L may be considered for treatment 5. This treatment addresses thyroid-related symptoms (fatigue, cognitive impairment, cardiovascular risk) but will not resolve hirsutism 3, 5.
Treatment Implications
Treating thyroid dysfunction will NOT improve hirsutism, as the mechanisms are unrelated 6, 1:
For Hirsutism Management
- First-line pharmacologic therapy: combination estrogen-progestin or antiandrogens (cyproterone acetate, spironolactone) 6
- Second-line options: finasteride, GnRH agonists, or glucocorticoids in selected cases 6
- Cosmetic measures are frequently required as systemic therapy reduces hair growth in less than 50% of cases 6
For Concurrent Thyroid Disease
- Levothyroxine for hypothyroidism to address metabolic, cardiovascular, and cognitive effects 3, 5
- Careful dose titration to avoid iatrogenic subclinical hyperthyroidism, which increases osteoporosis and cardiovascular risk in postmenopausal women 5
Critical Pitfalls to Avoid
Do not attribute hirsutism to thyroid dysfunction and delay appropriate androgen-directed therapy. The statement that thyroid disorders cause hirsutism represents a diagnostic error that will lead to:
- Missed diagnosis of PCOS or other androgen excess states 1
- Delayed treatment with antiandrogens or combination hormonal therapy 6
- Unnecessary focus on thyroid management that will not address the cosmetic concern 6, 1
Always screen for thyroid dysfunction in postmenopausal women with hirsutism, but recognize this is to identify comorbidity, not causality 4, 2. The high prevalence of thyroid disease in this population (>25%) makes concurrent diagnosis likely, but the two conditions require separate, targeted management 3, 5.