Osteoporosis Prevention for Women: DEXA Scans, Calcium, and What Actually Protects Your Bones

You probably don't think about your bones. They're invisible, structural, boring. You'll think about them when you break one — and by then, you've already lost years of bone density that you can't easily get back. Osteoporosis is a condition where prevention is dramatically more effective than treatment, yet most women don't take action until they've already fractured.

One in two women over 50 will break a bone due to osteoporosis in their lifetime. Hip fractures carry a 20% one-year mortality rate in older adults. These aren't just statistics — they represent real women who fell, broke a hip, went to the hospital, and never fully recovered.

How Bones Work (and How They Break Down)

Bone is living tissue, constantly being remodeled. Osteoblasts build new bone; osteoclasts break down old bone. Until about age 30, you build more than you break down (net gain). After 30, breakdown gradually exceeds building (net loss). This is normal aging.

What's not normal — but is common — is accelerated bone loss. And the single biggest accelerator is estrogen decline.

Menopause is a bone crisis. In the 5-7 years surrounding menopause, women can lose up to 20% of their bone density. Estrogen is a key regulator of osteoclast activity — when estrogen drops, osteoclast activity increases, and bone is resorbed faster than it can be rebuilt.

Other factors that accelerate bone loss:

• Early menopause (before 45) or surgical menopause
• Prolonged amenorrhea (from any cause — eating disorders, hypothalamic amenorrhea, excessive exercise)
• Glucocorticoid use (prednisone for more than 3 months)
• Thyroid excess (hyperthyroidism or excessive thyroid hormone replacement)
• Low body weight (BMI below 20)
• Smoking
• Excessive alcohol (3+ drinks daily)
• Malabsorption conditions (celiac disease, inflammatory bowel disease)
• Type 1 diabetes
• Rheumatoid arthritis
• Family history of osteoporosis or hip fracture
• Certain medications (aromatase inhibitors, some anticonvulsants, depot medroxyprogesterone)

DEXA Scan Guidelines

A DEXA (dual-energy X-ray absorptiometry) scan is the gold standard for measuring bone mineral density. Here's who should get one:

Universal screening:

• All women at age 65
• All men at age 70

Earlier screening if risk factors are present:

• Postmenopausal women under 65 with risk factors
• Women with early menopause (before 45)
• Anyone on chronic glucocorticoids
• Anyone with a fragility fracture (fracture from minimal trauma)
• Conditions associated with bone loss (see list above)

Understanding your results:

• T-score — Compares your bone density to a healthy 30-year-old. This is the diagnostic number.

- Above -1.0: Normal

- -1.0 to -2.5: Osteopenia (low bone mass)

- Below -2.5: Osteoporosis

- Below -2.5 with a fragility fracture: Severe osteoporosis

• FRAX score — A 10-year fracture risk calculator that combines your T-score with clinical risk factors. Treatment is typically recommended when 10-year risk of major osteoporotic fracture exceeds 20% or hip fracture risk exceeds 3%.

How often to repeat: Every 1-2 years if you're on treatment or have osteopenia, to track response. Every 2-5 years for monitoring stable osteopenia without treatment.

Calcium: What the Evidence Actually Says

Calcium is essential for bone health, but the story is more nuanced than "take a supplement."

Dietary calcium is preferred over supplements. The goal is 1,000-1,200 mg daily from all sources combined.

Good food sources:

• Dairy (milk, yogurt, cheese) — approximately 300 mg per serving
• Fortified plant milks and orange juice
• Sardines and canned salmon with bones
• Leafy greens (kale, collard greens, broccoli — but not spinach, which has oxalates that block absorption)
• Tofu made with calcium sulfate

If supplementing:

• Take no more than 500-600 mg at a time (absorption decreases with larger doses)
• Calcium carbonate is the most common and cheapest — take with food for absorption
• Calcium citrate can be taken without food and is better tolerated with acid-suppressing medications
• Don't exceed 2,000-2,500 mg total daily calcium from all sources — excessive calcium may increase cardiovascular and kidney stone risk

Vitamin D: The Calcium Partner

Vitamin D is essential for calcium absorption. Without adequate vitamin D, you can take all the calcium you want and your body won't absorb it properly.

Target level: 30-50 ng/mL (25-hydroxyvitamin D)

Dosing:

• 600-800 IU daily is the minimum recommendation for adults
• Many experts recommend 1,000-2,000 IU daily for most adults, especially those with limited sun exposure
• If your level is below 20 ng/mL, higher loading doses (50,000 IU weekly for 8-12 weeks) followed by maintenance may be needed
• Vitamin D3 (cholecalciferol) is preferred over D2 (ergocalciferol)

Get your level checked. Supplementation should be guided by your actual vitamin D level, not guesswork.

Exercise That Builds Bone

Not all exercise is equal for bone health. Bone responds to mechanical stress — you need to load it to stimulate remodeling.

Weight-bearing impact exercise (most effective):

• Walking, jogging, running
• Dancing
• Stair climbing
• Tennis, pickleball, basketball
• Jump training (even 10-20 jumps daily may help)

Resistance training (essential):

• Target major muscle groups 2-3 times weekly
• Progressive overload — gradually increase weights
• Squats, deadlifts, presses, rows
• Resistance training also reduces fall risk by improving strength and balance

Balance training (prevents falls):

• Tai chi
• Single-leg stands
• Yoga
• Balance board exercises

What doesn't help: Swimming and cycling. Excellent for cardiovascular health but minimal bone-building stimulus because they're non-weight-bearing.

Medications for Osteoporosis

When lifestyle measures aren't enough, several medication classes are available:

Bisphosphonates (First-Line)

• Alendronate (Fosamax) — Weekly oral tablet
• Risedronate (Actonel) — Weekly or monthly oral tablet
• Zoledronic acid (Reclast) — Annual IV infusion
• Ibandronate (Boniva) — Monthly oral or quarterly IV

How they work: Inhibit osteoclast activity, slowing bone breakdown.

Effectiveness: Reduce vertebral fractures by 40-70% and hip fractures by 40-50%.

Duration: Typically 3-5 years, then a "drug holiday" may be considered (bisphosphonates persist in bone for years after discontinuation).

Concerns: Rare side effects include osteonecrosis of the jaw and atypical femur fractures with prolonged use. These are genuinely rare but have disproportionately influenced patient fear.

Denosumab (Prolia)

• Subcutaneous injection every 6 months
• RANKL inhibitor — prevents osteoclast maturation
• Highly effective, especially at the hip
• Important: You cannot stop denosumab abruptly. Discontinuation causes rapid bone loss and rebound fracture risk. Must transition to a bisphosphonate if stopping.

Anabolic Agents

• Teriparatide (Forteo) — PTH analog, daily injection for up to 2 years. Builds new bone rather than just preventing loss.
• Abaloparatide (Tymlos) — Similar to teriparatide with possibly faster onset
• Romosozumab (Evenity) — Sclerostin inhibitor. Monthly injection for 12 months. Both builds bone and reduces breakdown. Most potent agent available for severe osteoporosis. Cardiovascular risk warning — not for patients with recent MI or stroke.

HRT

Hormone replacement therapy remains effective for osteoporosis prevention in perimenopausal and early postmenopausal women. The WHI demonstrated significant fracture reduction with HRT. For women taking HRT for menopausal symptoms, bone protection is an added benefit.

Don't Wait for the Fracture

The tragedy of osteoporosis is that it's silent until it's not. You don't feel bone loss. You don't know your bones are thin until you fall and break something — or until you develop compression fractures in your spine that steal inches from your height and cause chronic pain.

Prevention starts now, regardless of your age:

• In your 30s: Build peak bone mass with exercise and nutrition
• In your 40s: Assess risk factors, optimize calcium and vitamin D
• In your 50s: Get a DEXA scan if risk factors are present, consider HRT
• At 65: Universal DEXA screening

If you're concerned about your bone health or have risk factors for osteoporosis, [start a visit at coral.clinic/start](https://coral.clinic/start). Dr. Kim can assess your risk, order appropriate screening, and develop a prevention or treatment plan before the first fracture happens.