DEXA Bone Density: Evidence-Based Ways to Improve Your Number

What Your DEXA Score Actually Means

Your DEXA report will show two numbers: a T-score and a Z-score. The T-score compares your bone mineral density (BMD) to a young healthy adult reference population at peak bone mass. The Z-score compares you to age- and sex-matched peers. Both matter, but they answer different questions.

The World Health Organization defines osteoporosis as a T-score of -2.5 or below at the femoral neck, total hip, or lumbar spine. A T-score between -1.0 and -2.5 is called osteopenia. A score at or above -1.0 is considered normal.

T-Score vs. Z-Score: Which One Should You Watch?

For postmenopausal women and women over 50, the T-score is the standard diagnostic anchor. For premenopausal women, children, and women under 50, the International Society for Clinical Densitometry recommends using the Z-score instead, because comparing a 35-year-old to a 25-year-old peak-bone-mass reference makes little clinical sense. A Z-score of -2.0 or below in a premenopausal woman is described as "below the expected range for age" and warrants a secondary-cause workup.

Why DEXA Is Not the Whole Picture

DEXA measures density, not architecture. Two women can have identical T-scores and different fracture risk depending on bone quality, fall risk, and prior fractures. That is why your clinician will pair your DEXA result with the FRAX fracture risk calculator, which incorporates age, prior fracture, parental hip fracture, smoking, glucocorticoid use, rheumatoid arthritis, and secondary causes of osteoporosis to produce a 10-year fracture probability.

How Bone Loss Works Differently in Women

Women are disproportionately affected by osteoporosis. Approximately 80% of the 10 million Americans with osteoporosis are women. That is not coincidence. It reflects sex-specific biology at every stage of life.

Reproductive Years

Peak bone mass is reached by the late 20s. Estrogen is the primary regulator of bone remodeling in women. It slows osteoclast (bone-resorbing cell) activity. Any condition that suppresses estrogen during the reproductive years, including hypothalamic amenorrhea, hyperprolactinemia, premature ovarian insufficiency (POI), or the female athlete triad, accelerates bone loss.

Women with PCOS who have irregular cycles may also have suboptimal bone accrual if ovulation is suppressed chronically, although some data suggest the elevated androgens and BMI in PCOS may partially offset this. The data in this group remain mixed, and no dedicated PCOS-specific bone guideline exists yet.

Perimenopause: The Critical Window

Bone loss accelerates sharply in the perimenopause-to-early-postmenopause transition. Studies using high-resolution imaging show women can lose 10-20% of their trabecular bone mass in the 5-year window bracketing the final menstrual period. This is the window when lifestyle interventions have the greatest preventive impact and when menopausal hormone therapy (MHT) has the strongest data for bone preservation.

Postmenopause

After menopause, estrogen deficiency drives a sustained increase in bone turnover markers. The Women's Health Initiative (WHI) randomized trial showed combined estrogen-progestogen therapy reduced hip fracture risk by 34% compared with placebo over 5 years. That benefit is real, though MHT is not prescribed solely for bone protection in most women because the overall risk-benefit calculation is individualized.

Pregnancy and Postpartum

Pregnancy-associated osteoporosis is rare but under-recognized. The fetus draws roughly 30 grams of calcium from the maternal skeleton across gestation. BMD at the spine can fall 3-5% during pregnancy and lactation, recovering substantially within 12-18 months of weaning in most women. Women with low pre-pregnancy bone mass or prolonged lactation are at higher risk for vertebral fractures.

Who Should Get a DEXA Scan

The USPSTF recommends DEXA screening for all women aged 65 and older and for younger postmenopausal women whose 10-year fracture risk equals or exceeds that of a 65-year-old white woman with no risk factors (approximately 9.3% by FRAX). The American College of Obstetricians and Gynecologists (ACOG) aligns with this threshold but also recommends screening for:

• Women with POI or early menopause (under 45)
• Women who have used glucocorticoids for more than 3 months
• Women with rheumatoid arthritis, inflammatory bowel disease, or malabsorption syndromes
• Women with a history of bariatric surgery
• Women with a prior low-trauma fracture after age 40

If you take aromatase inhibitors for breast cancer, your oncologist should arrange baseline and annual DEXA scans, as these drugs cause substantial and rapid bone loss.

Evidence-Based Ways to Improve Your Bone Density

Exercise: Load the Bone to Build the Bone

Bone responds to mechanical load. The most effective exercise types for BMD are progressive resistance training and high-impact weight-bearing activity. A 2022 meta-analysis in the British Journal of Sports Medicine found that resistance training significantly improved lumbar spine BMD in postmenopausal women, with a mean difference of 0.59 g/cm².

Resistance Training

Aim for 2-3 sessions per week targeting major muscle groups. Progressive overload matters. Start with a load you can lift 8-12 times with good form, and increase resistance as strength improves. Hip and spine are the sites that count most on DEXA, so prioritize squats, deadlifts, hip thrusts, and rows.

Impact Exercise

Jogging, jumping, tennis, and dancing all generate ground-reaction forces that stimulate osteoblast activity. For postmenopausal women at risk of falls, the impact type should be matched to fall risk. High-impact plyometrics may not be appropriate if balance is already compromised.

Balance and Fall Prevention

A fracture is the clinical endpoint that actually matters. Tai chi has level I evidence for fall reduction. The ACSM recommends balance training at least 2 days per week for women over 65.

Nutrition: Calcium and Vitamin D Are the Foundation

Calcium

The National Osteoporosis Foundation recommends 1,000 mg/day of elemental calcium for women under 50 and 1,200 mg/day for women 50 and older. Food-first is the preferred strategy. Dairy, fortified plant milks, tinned fish with bones, tofu set with calcium sulfate, and leafy greens all contribute. Supplemental calcium should fill the gap, not replace diet entirely. Calcium carbonate requires stomach acid and should be taken with food. Calcium citrate is better absorbed in women with low stomach acid or who take proton pump inhibitors.

Vitamin D

Vitamin D deficiency impairs calcium absorption and suppresses bone formation. The Endocrine Society guideline recommends at least 1,500-2,000 IU/day of vitamin D3 for adults at risk of deficiency. Target serum 25-hydroxyvitamin D of at least 30 ng/mL (75 nmol/L). Women with obesity, limited sun exposure, malabsorption, or darker skin pigmentation often need higher doses, sometimes 3,000-4,000 IU/day, to reach this target.

Protein

Adequate dietary protein supports the collagen matrix that gives bone its tensile strength. An analysis from the Nurses' Health Study found that higher protein intake was associated with lower hip fracture risk. Target at least 1.0-1.2 g of protein per kilogram of body weight per day, and closer to 1.2-1.6 g/kg if you are in active resistance training.

Lifestyle Factors That Directly Harm Bone

Several modifiable behaviors accelerate bone loss and should be addressed alongside any positive intervention.

• Smoking. Smoking reduces estrogen and impairs bone blood supply. Women who smoke have BMD approximately 5-10% lower at the hip than non-smokers.
• Alcohol. More than 2 standard drinks per day suppresses osteoblast function and raises fracture risk. Modest intake (under 1 drink/day) appears neutral.
• Very low body weight. A BMI <18.5 is an independent fracture risk factor. Estrogen produced by adipose tissue partially protects postmenopausal bone.
• Prolonged sitting and sedentary behavior. Even controlling for exercise, long uninterrupted sitting is associated with lower hip BMD.

Prescription Therapy: When Lifestyle Is Not Enough

The decision to start pharmacotherapy rests on three inputs working together: your T-score, your FRAX 10-year probability, and your life stage. Below is a practical framework for women.

Postmenopausal women. The AACE/ACE clinical practice guideline (2020) recommends treatment for:

• Osteoporosis by T-score (at or below -2.5) regardless of FRAX
• Osteopenia (-1.0 to -2.5) PLUS a 10-year hip fracture probability at or above 3% or major osteoporotic fracture probability at or above 20%
• Any prior hip or vertebral fracture, even with a normal T-score

Bisphosphonates (Alendronate, Risedronate, Zoledronic Acid)

Bisphosphonates are first-line for most postmenopausal women. Alendronate 70 mg orally once weekly is the most widely studied, and the FIT (Fracture Intervention Trial) demonstrated a 47% reduction in hip fracture over 3 years in women with low BMD and prior vertebral fracture. Risedronate 35 mg weekly or 150 mg monthly is an alternative with similar efficacy. Zoledronic acid 5 mg IV once yearly is preferred when gastrointestinal tolerability is a concern or adherence is a barrier.

Denosumab (Prolia)

Denosumab 60 mg subcutaneously every 6 months is an alternative for postmenopausal osteoporosis, particularly in women who cannot tolerate oral bisphosphonates. The FREEDOM trial showed a 68% reduction in vertebral fracture risk over 3 years. A critical caveat: do not stop denosumab without a transition plan. Discontinuation causes a rebound increase in bone turnover that can result in multiple vertebral fractures within 12-18 months.

Romosozumab and Teriparatide (Anabolic Agents)

For women with very high fracture risk (T-score at or below -2.5 plus prior fracture, or T-score at or below -3.0), anabolic agents that build new bone before anti-resorptive consolidation may be appropriate. Romosozumab (Evenity) 210 mg subcutaneously monthly for 12 months, followed by bisphosphonate, reduced major osteoporotic fractures by 27% versus alendronate alone in the ARCH trial. Romosozumab carries a black-box warning for cardiovascular events and should not be used in women with a history of heart attack or stroke.

Menopausal Hormone Therapy

MHT is not FDA-approved as primary osteoporosis therapy, but it does preserve BMD during the perimenopause transition and early postmenopause. For women under 60 or within 10 years of menopause onset who have menopausal symptoms AND bone concerns, MHT addresses both simultaneously. The Menopause Society 2023 position statement states that MHT is appropriate for the prevention of bone loss and osteoporosis in women at elevated risk who are within this window.

Premenopausal Women With Low Bone Mass

Bisphosphonates are generally avoided in premenopausal women who have not completed childbearing because they incorporate into bone for years and their fetal safety profile is not established in human data. For premenopausal women with secondary osteoporosis (from eating disorders, glucocorticoids, or hypogonadism), addressing the underlying cause is the first priority. If estrogen deficiency is the driver, estrogen replacement (via combined oral contraceptives or transdermal estradiol) is preferred over bisphosphonates.

Pregnancy and Lactation Considerations

Bisphosphonates are contraindicated in pregnancy. They cross the placenta, incorporate into fetal bone, and have been associated with neonatal hypocalcemia in case reports. Because bisphosphonates remain in bone for years to decades, any woman of reproductive age starting alendronate, risedronate, or zoledronic acid should use reliable contraception and should discuss planned pregnancies with her prescriber before starting.

Denosumab is also not recommended in pregnancy. It is a monoclonal antibody (IgG2) and transfers across the placenta in the second and third trimesters. Animal data show skeletal abnormalities at high doses. The FDA labels denosumab Pregnancy Category X for its bone-modifying indication and requires a negative pregnancy test before each injection and contraception during and for at least 5 months after the final dose.

Romosozumab has shown teratogenicity in animal studies and is contraindicated in pregnancy.

Lactation: Calcium and vitamin D supplementation are safe and encouraged during breastfeeding. The transient BMD loss of lactation is physiologically normal and largely reversible. Women should not delay or shorten breastfeeding out of bone concern. If a woman is already on prescription therapy and unexpectedly becomes pregnant or begins lactating, she should contact her prescriber immediately rather than stopping on her own.

The evidence gap here is real. Most key fracture trials in this field enrolled postmenopausal women aged 55-80. Data on pharmacological bone protection in premenopausal women are largely derived from secondary analyses, case series, and extrapolation. Shared decision-making should acknowledge this explicitly.

Conditions That Specifically Affect Bone Health in Women

Several conditions common in women accelerate bone loss and should prompt earlier DEXA screening or more aggressive targets.

• PCOS. Evidence is mixed. Elevated androgens and adiposity may be partially protective, but chronic anovulation and low estrogen phases may not be.
• Endometriosis. GnRH agonist therapy (leuprolide) used to treat endometriosis causes significant and rapid bone loss. Women using GnRH agonists for more than 6 months should receive add-back hormone therapy and DEXA monitoring per ACOG Practice Bulletin 114.
• Thyroid disease. Both untreated hyperthyroidism and over-suppressive levothyroxine doses in thyroid cancer reduce BMD. A meta-analysis found TSH suppression below 0.1 mIU/L is associated with a 2.5-fold increase in vertebral fracture risk in postmenopausal women.
• Celiac disease and inflammatory bowel disease. Malabsorption reduces calcium and vitamin D absorption independent of dietary intake.
• Premature ovarian insufficiency. POI before age 40 removes estrogen decades earlier than natural menopause. Without estrogen therapy, these women face substantially higher lifetime fracture risk.
• Female athlete triad / relative energy deficiency in sport (RED-S). Low energy availability suppresses the hypothalamic-pituitary-ovarian axis, drops estrogen, and causes bone loss that may be irreversible if prolonged.

Reading Your DEXA Report With Your Clinician

When your result arrives, ask four specific questions:

1. What is my T-score at each site (lumbar spine, total hip, femoral neck)? The lowest T-score at any of these sites drives the diagnosis.
2. What is my FRAX 10-year fracture probability, with and without BMD entered?
3. Am I being compared against a female reference database? DEXA software defaults vary by machine, and some older systems used a male normative dataset.
4. If this is a follow-up scan, was it performed on the same machine using the same acquisition protocol? A 3-5% change in BMD on DEXA falls within the machine's least significant change (LSC) threshold, so small apparent changes may not be real.

The International Society for Clinical Densitometry recommends that follow-up scans use the same machine, same acquisition, and be read by a densitometrist or clinician trained in DEXA interpretation to minimize measurement error.

"A single DEXA scan should never be interpreted in isolation. The clinical context, fracture history, bone turnover markers, and trajectory over serial scans all inform what the number actually means for that woman," says Rachel Goldberg, MD, WomanRx medical reviewer and board-certified OB-GYN.

Who This Approach Is Right For (and Who Needs a Different Plan)

Start with lifestyle and monitoring if:

• Your T-score is in the normal range (-1.0 or above) at any life stage
• You have osteopenia (T-score -1.0 to -2.5) with a low FRAX probability and no prior fracture
• You are premenopausal with a secondary cause that is being actively treated

Add prescription therapy if:

• Your T-score is at or below -2.5
• You have had a low-trauma fracture at any site after age 40
• You have osteopenia AND a FRAX 10-year hip fracture probability at or above 3% or major osteoporotic fracture probability at or above 20%
• You are on aromatase inhibitors or long-term glucocorticoids

A specialist referral is warranted if:

• Your Z-score is at or below -2.0 (premenopausal)
• Your bone loss is faster than expected despite treatment
• You have had two or more vertebral fractures
• You have a suspected secondary cause that has not been identified

Your next step after reviewing this article is to request your FRAX probability from your clinician and ask specifically whether your DEXA was performed and interpreted using a female normative reference standard.