Low Bone Density in Young Women: Causes and What to Do

Is it normal to have low bone density before menopause?

No. Peak bone mass is typically achieved between the late teens and mid-twenties, and bone density in a young adult should be near its lifetime high. When a DEXA scan shows osteopenia (T-score between -1.0 and -2.5) or osteoporosis (T-score at or below -2.5) in a woman under 40, current guidelines describe this as secondary osteoporosis — meaning a specific cause should be sought rather than attributing it to normal aging 1Ref 1Eastell R, Rosen CJ, Black DM, Cheung AM, Murad MH, Shoback D (2019).Pharmacological Management of Osteoporosis in Postmenopausal Women: An Endocrine Society Clinical Practice Guideline.Framework for osteoporosis management and classification; secondary osteoporosis concept.

The USPSTF does not recommend routine bone density screening for women under 65 without risk factors, precisely because it is expected to be normal in that population. Discovering low density at a young age almost always signals something that needs evaluation 2Ref 2US Preventive Services Task Force (2018).Screening for Osteoporosis to Prevent Fractures: US Preventive Services Task Force Recommendation Statement.USPSTF not recommending routine bone density screening under age 65 without risk factors.

What conditions can cause low bone density in young women?

Hormonal causes

Estrogen is a primary regulator of bone remodeling. When estrogen is low, bone breakdown outpaces bone formation. Causes of low estrogen in young women include:

• Functional hypothalamic amenorrhea: Missing periods due to underfueling, excessive exercise, or chronic stress. This is common in athletes and in people who restrict calories without a formal eating disorder diagnosis.
• Eating disorders: Anorexia nervosa is associated with some of the most severe bone loss seen in young women, resulting from a combination of low estrogen, nutritional deficiencies, and cortisol elevation from physical stress.
• Premature ovarian insufficiency (POI): Loss of ovarian function before age 40, leading to early and prolonged estrogen deficiency.
• PCOS: Paradoxically, PCOS involves irregular periods but typically does not cause low bone density; bone density is often preserved or higher in PCOS due to elevated androgen and sometimes estrogen levels.

Nutritional and malabsorption causes

• Calcium and vitamin D deficiency: Both are essential for bone mineralization. Low vitamin D is prevalent in the general population and compounds bone loss from other causes 3Ref 3Di Molfetta IV, Bordoni L, Gabbianelli R, Sagratini G, Alessandroni L (2024).Vitamin D and Its Role on the Fatigue Mitigation: A Narrative Review.Vitamin D deficiency prevalence and its role in bone and systemic health.
• Celiac disease: Impairs calcium and vitamin D absorption even when diet appears adequate. Often undiagnosed.
• Inflammatory bowel disease: Chronic intestinal inflammation and malabsorption affect bone health.

Medication-related causes

• Glucocorticoids (corticosteroids): Long-term use — even at modest doses — is one of the most common drug-induced causes of bone loss. Inhaled corticosteroids used daily over years can also have an effect.
• Certain antiepileptic drugs: Affect vitamin D metabolism.
• Proton pump inhibitors: Long-term use has been associated with modestly reduced calcium absorption.
• Depot medroxyprogesterone acetate (Depo-Provera): Some data associate prolonged use with temporary reductions in bone density that typically recover after stopping.

Other medical causes

• Hyperthyroidism or excessive thyroid hormone replacement
• Hyperparathyroidism
• Rheumatoid arthritis and other inflammatory conditions
• Chronic kidney disease

What tests are used to evaluate low bone density in a young woman?

Evaluation generally starts with blood and urine tests to look for underlying causes. Common components include:

• Calcium, phosphorus, alkaline phosphatase
• 25-hydroxyvitamin D
• Parathyroid hormone (PTH)
• Thyroid function (TSH)
• Celiac antibodies (tissue transglutaminase IgA with total IgA)
• Estradiol and FSH to assess ovarian function
• Cortisol if Cushing syndrome is suspected
• Complete blood count, comprehensive metabolic panel
• Urinary calcium to assess absorption and excretion

A DEXA scan of the spine and hip provides the baseline bone mineral density measurement. In young adults, clinicians may use Z-scores (which compare bone density to age-matched peers) rather than T-scores (which compare to a young adult reference) for a more accurate assessment.

Which specialist should evaluate low bone density in a young woman?

An endocrinologist is typically the right specialist for most causes of low bone density in young women, particularly when the cause is hormonal or when pharmacologic treatment is being considered. Rheumatologists also manage bone health, particularly when inflammatory conditions are involved.

If an eating disorder is identified or suspected, an eating disorder specialist or a multidisciplinary team (including psychiatry, dietetics, and medicine) is the appropriate pathway — eating disorder treatment is the most direct route to recovering bone in those cases.

For guidance on calcium and vitamin D or lifestyle factors, a primary care clinician at Gale can also be a starting point, coordinating referrals as needed.

Can bone density be recovered or improved?

It depends on the cause and how long the deficiency has been present. The most reliable path to bone density recovery in young women is treating the underlying cause:

• Restoring periods and adequate nutrition in amenorrhea and eating disorders
• Correcting vitamin D and calcium deficiency 3Ref 3Di Molfetta IV, Bordoni L, Gabbianelli R, Sagratini G, Alessandroni L (2024).Vitamin D and Its Role on the Fatigue Mitigation: A Narrative Review.Vitamin D deficiency prevalence and its role in bone and systemic health
• Treating celiac disease (gluten-free diet improves bone density over time)
• Addressing hormonal deficiencies with guidance from an endocrinologist

Pharmacologic agents used in postmenopausal osteoporosis (bisphosphonates, for example) are generally used more cautiously in premenopausal women due to long half-lives and uncertain effects in this population. The Endocrine Society guideline on postmenopausal osteoporosis provides the framework for pharmacotherapy decisions 1Ref 1Eastell R, Rosen CJ, Black DM, Cheung AM, Murad MH, Shoback D (2019).Pharmacological Management of Osteoporosis in Postmenopausal Women: An Endocrine Society Clinical Practice Guideline.Framework for osteoporosis management and classification; secondary osteoporosis concept, though premenopausal management differs and typically prioritizes reversing the underlying cause first.

Bone is living tissue and does remodel, especially in younger people. Recovery is possible, but the window of opportunity — particularly for reaching optimal peak bone mass — is limited.