DEXA and Coronary Calcium Score: The Two Tests Women Over 45 Need Together

She is 51. Her gynecologist recommended a DEXA scan at her annual visit. Her cardiologist recommended a coronary artery calcium score. She had neither done.

Both of these imaging tests provide information that her standard blood work cannot provide. Both are changed by the menopausal transition. Both can shift clinical decisions. They are often discussed in separate specialty silos: bone health over here, cardiovascular risk over there. The biology doesn’t separate them that cleanly.

What estrogen decline does to bone and to arteries

Estrogen is a structural protector of two distinct tissues: bone and arterial endothelium. When estrogen declines at menopause, both systems lose a regulatory input simultaneously.

In bone: Estrogen suppresses osteoclast activity (cells that resorb bone) and promotes osteoblast activity (cells that build bone). As estrogen falls in perimenopause, osteoclast activity accelerates, bone resorption outpaces formation, and trabecular bone density falls by approximately 1-2% per year in the first 5-7 years after the final menstrual period. This is the window of maximum bone loss risk. 5 / Solid

In arteries: Estrogen maintains endothelial nitric oxide synthase activity, supports HDL, suppresses LDL receptor degradation, reduces inflammatory cytokines, and inhibits smooth muscle cell proliferation. Its decline removes these protective mechanisms, and the accelerated atherosclerosis risk that characterizes post-menopausal women begins accumulating.

The result: a woman who enters menopause at 51 is simultaneously entering her peak bone loss window and her cardiovascular risk acceleration window. These are not coincidental, they have a common hormonal driver.

The DEXA scan: what it measures and what it means

DEXA (dual-energy X-ray absorptiometry) measures bone mineral density at two primary sites: the lumbar spine and the femoral neck (hip). Results are reported as a T-score, which compares your bone density to the reference peak (young adult) bone density:

• T-score -1.0 and above: Normal
• T-score -1.0 to -2.5: Osteopenia (low bone density, elevated fracture risk)
• T-score -2.5 and below: Osteoporosis

Current USPSTF guidelines recommend DEXA at age 65 for average-risk women. This recommendation does not account for the 14-year window between age 51 (average menopause) and 65, during which substantial bone loss can occur silently. For women with additional risk factors, earlier testing makes clinical sense: 4 / Promising

• Premature or surgical menopause
• Family history of hip fracture
• Low body weight (BMI under 20)
• Chronic glucocorticoid use (equivalent to 5mg prednisone per day for 3 months or more)
• Rheumatoid arthritis or other inflammatory conditions
• Celiac disease or malabsorption syndromes affecting calcium absorption

The FRAX tool (Fracture Risk Assessment Tool) incorporates clinical risk factors to estimate 10-year fracture probability, and can guide early DEXA ordering even before 65.

What DEXA cannot tell you: DEXA measures bone mineral density but not bone quality or microarchitecture. Two women can have the same T-score with different bone architecture quality. Trabecular Bone Score (TBS) is an analysis added to standard DEXA that assesses bone texture as a proxy for microarchitecture, it provides additional fracture risk information beyond the T-score and is increasingly available at major centers.

The coronary artery calcium score: what it measures and what it means

A CAC score (coronary artery calcium score) is a low-radiation CT scan of the chest that takes approximately 10 minutes. No contrast is injected. It measures calcium deposits in the walls of the coronary arteries, calcium that is present only in atherosclerotic plaque. 5 / Solid

Results are reported as an Agatston score:

• 0: No detectable coronary calcium, very low short-term event risk
• 1-99: Mild calcification, low-moderate risk
• 100-399: Moderate calcification, elevated risk
• 400+: Significant calcification, high risk

The clinical value of CAC scoring is in reclassification: moving patients out of the uncertain “intermediate risk” category (10-year cardiovascular event risk 7.5-20% by pooled cohort equations) into either a lower-risk category (CAC 0, defer statin) or a higher-risk category (CAC above 100, initiate statin) where the treatment decision becomes clearer.

For women specifically, CAC scoring is particularly valuable because standard cardiovascular risk calculators frequently underestimate women’s risk by not including Lp(a), prior preeclampsia, premature menopause, or other female-specific risk modifiers. A woman who appears at 8% 10-year risk by the Pooled Cohort Equations may have a CAC of 200 that places her at substantially higher risk, changing the statin decision.

CAC limitations: CAC measures calcified plaque. Non-calcified plaque (which is more common in younger women) is not detected. A CAC score of 0 does not exclude soft plaque, microvascular disease, or Lp(a)-related thrombotic risk. It is one imaging test in a comprehensive risk assessment, not a complete risk assessment on its own.

When the tests inform each other

Low bone density and elevated coronary calcium frequently coexist, not just because of shared risk factors, but because the biological pathways overlap.

Vitamin K2 and calcification. Vitamin K2 (specifically MK-7 form) activates osteocalcin (which binds calcium into bone) and matrix Gla protein (which inhibits arterial calcification). Vitamin K2 deficiency is associated with both lower bone density and higher arterial calcification. The therapeutic implication is speculative but biologically plausible: ensuring adequate vitamin K2 through diet (fermented foods, some dairy) or supplementation may support both bone calcium retention and arterial calcium inhibition. Evidence from RCTs is preliminary. 3 / Early

Inflammation as shared driver. Chronic low-grade inflammation accelerates both osteoclast activity (bone resorption) and endothelial dysfunction (arterial disease progression). Women with elevated hs-CRP have higher rates of both osteoporosis and cardiovascular events, not independent of, but in addition to, their other risk factors.

RANKL pathway. RANK ligand (RANKL) is produced by osteoblasts and regulates osteoclast activity. RANKL signaling also occurs in the arterial wall and may contribute to arterial calcification. Denosumab, a RANKL inhibitor used to treat osteoporosis, has shown some association with reduced cardiovascular calcification in preliminary data, a mechanistic connection being explored in ongoing research. 3 / Early

Calcium supplementation: the actual evidence

The calcium supplement and cardiovascular risk question is genuinely unsettled, and the answer matters practically for women managing bone loss.

The MESA cohort study (over 5,000 adults followed for 10 years) found that calcium from food was associated with lower cardiovascular risk, while calcium from supplements was associated with higher coronary artery calcification at follow-up. 4 / Promising

The Women’s Health Initiative supplementation trial (calcium 1,000mg/day plus vitamin D 400 IU) did not show a statistically significant cardiovascular harm overall, but a subgroup analysis of women not already taking personal calcium supplements at trial entry suggested a possible increased coronary event risk with supplementation.

Current guidance from most professional societies:

• Prefer dietary calcium sources when possible: dairy (300mg per 8oz milk), fortified plant milks, salmon with bones, kale, bok choy
• If supplementation is necessary, use the minimum effective dose (500mg elemental calcium per dose, not 1000mg) with adequate vitamin D3 (1500-2000 IU daily) to enhance absorption
• Calcium citrate is absorbed without requiring stomach acid (better for women on acid-reducing medications); calcium carbonate requires acid for absorption and is best taken with food

When DEXA shows osteopenia or osteoporosis: what changes

Osteopenia (T-score -1.0 to -2.5):

Osteopenia is not a disease requiring treatment in all cases; it is a risk state that requires assessment of fracture probability and a decision about intervention. The FRAX tool (available at sheffield.ac.uk/FRAX) calculates 10-year probability of major osteoporotic fracture using T-score, age, weight, prior fracture history, parental hip fracture history, smoking, alcohol, glucocorticoid use, and rheumatoid arthritis. This calculation is more informative than T-score alone.

Interventions for osteopenia with intermediate-to-high FRAX risk:

Resistance and weight-bearing exercise. Mechanical loading is the primary stimulus for osteoblast activation and bone formation. Weight-bearing aerobic exercise (walking, jogging) combined with progressive resistance training produces measurable bone density improvement or maintenance in osteopenic women in randomized trials. This is not a mild adjunct; it is the most consistently effective non-pharmacological intervention. 4 / Promising

Calcium and vitamin D3 adequacy. Total elemental calcium intake of 1000-1200 mg per day (from diet plus supplement if needed) and vitamin D3 of at least 1500-2000 IU daily to maintain 25-OH vitamin D above 40-60 ng/mL provide the raw substrate for bone mineralization.

MHT in perimenopausal women. Menopausal hormone therapy provides significant bone protection, maintaining bone density during the peak-loss menopausal transition years. For women who are appropriate MHT candidates with concurrent osteopenia and significant menopausal symptoms, MHT addresses both simultaneously.

Bisphosphonates (alendronate, risedronate, zoledronic acid) are the first-line pharmacological treatment for osteoporosis (T-score below -2.5) or osteopenia with high FRAX fracture probability. They inhibit osteoclast activity, reduce bone resorption, and reduce fracture risk by 30-50% in trial data. The prescribing and duration decision requires physician-guided individualization.

Osteoporosis (T-score below -2.5):

A T-score below -2.5 generally warrants pharmacological treatment, particularly in women with one or more prior fragility fractures. Beyond bisphosphonates, denosumab (a RANKL inhibitor given by injection every 6 months) is used for women who cannot tolerate bisphosphonates or who have shown inadequate response. Romosozumab (a sclerostin inhibitor that both builds bone and reduces resorption) is reserved for women at very high fracture risk due to its significant efficacy profile.

When CAC is elevated: what changes in management

CAC 1-99 (mild calcification):

The presence of any coronary calcium confirms atherosclerotic plaque. This has two immediate implications: (1) lifestyle intensification is warranted — not “continue what you’re doing” but a specific conversation about diet, exercise, blood pressure targets, and smoking cessation as cardiovascular interventions, not health maintenance; and (2) the full cardiovascular risk profile should be completed if it hasn’t been, specifically Lp(a) and ApoB, which can be elevated even with otherwise favorable lipids. 5 / Solid

Statin therapy is commonly considered for CAC 1-99 in intermediate-risk women who were previously below the treatment threshold. The imaging has reclassified them.

CAC 100-399 (moderate calcification):

A CAC above 100 in a woman who appeared low-to-intermediate risk by calculated risk scores is a reclassification event. Statin therapy is generally indicated. The LDL target becomes more aggressive: typically below 100 mg/dL, or below 70 mg/dL if other risk factors are present. Blood pressure targets tighten. Aspirin in the primary prevention setting (no prior event) remains controversial and requires individual risk-benefit discussion.

Additional testing: if Lp(a) has not been measured, order it. If ApoB has not been measured, order it. A woman with CAC of 200 and Lp(a) of 120 mg/dL is in a substantially different position than a woman with the same CAC and Lp(a) of 15 mg/dL. The CAC confirms plaque; the Lp(a) explains the thrombotic risk attached to that plaque.

CAC 400+ (significant calcification):

This is high-risk territory. Statin therapy is indicated at high intensity. Cardiology referral for comprehensive risk assessment and treatment planning is appropriate. The 10-year event probability at CAC above 400, even in women with otherwise modest risk factors, approaches the risk level that drives secondary prevention discussions.

The case for testing in the menopausal window, not at 65

The USPSTF recommends DEXA at 65. Most primary care physicians do not order CAC scores routinely at any age. The result: the window of maximum actionability — the menopausal transition between 48 and 58, when both bone loss and cardiovascular risk are accelerating simultaneously — passes with neither test performed.

The argument for testing earlier is not that guidelines are wrong. USPSTF guidelines are appropriately conservative, optimized for average-risk populations at the population level. The argument is that perimenopausal women are not average-risk at average ages when it comes to bone and cardiovascular trajectories. They are entering a window of accelerated change that began at menopause — not at 65.

A woman who gets a DEXA at 52 and sees a T-score of -1.8 has 13 years to intervene pharmacologically and with exercise before the guideline-recommended screening age. A woman who waits until 65 and finds a T-score of -2.7 has a more limited range of remaining options to prevent the first fracture.

The same logic applies to CAC. A woman who gets a CAC at 52 and sees a score of 0 has reassuring imaging and a baseline for future comparison. A woman who sees a CAC of 150 at 52 has a decade-plus to modify the trajectory before becoming what her standard risk calculation would call “high-risk.” 4 / Promising

Neither test is a population-level recommendation for all women at menopause. Both are appropriate for the clinical conversation with a primary care physician or gynecologist at the time of menopause about what the transition means for bone and cardiovascular trajectories — and what information would be useful to have now rather than at the age standard screening begins.

How to get both tests

DEXA: Ordered by a primary care physician, gynecologist, or endocrinologist. If your physician says you don’t qualify before 65, ask about FRAX calculation to see whether your risk factors justify earlier screening. Most insurance covers DEXA at 65; earlier coverage varies by plan and indication.

CAC score: Ordered by primary care or a cardiologist. Some centers offer CAC scoring as a self-pay imaging test for approximately $75-150, without insurance. It is generally covered by insurance for patients at intermediate cardiovascular risk. Ask about scheduling at a hospital radiology center or dedicated cardiac imaging center.

Both together: These tests are often scheduled at different facilities and through different referral pathways, but both are imaging studies with results that should be incorporated into a single clinical picture. Bringing both results to a single appointment with a physician who can review them together (primary care, cardiologist, or internist) is the most efficient way to translate the results into action.

Related reading

For the five cardiovascular baseline numbers including CAC: The Five Numbers That Define Your Cardiac Baseline.

For ApoB and Lp(a) that complete the cardiovascular risk picture alongside CAC: ApoB and Lp(a) in Women.

For the menopausal transition driving these changes: Perimenopause Weight Gain and Visceral Fat.