Osteopenia

Does this patient have Osteopenia?

Osteopenia is defined by the World Health Organization. The diagnosis is based on the results of the dual- energy X-ray absorptiometry (DEXA) of the lumbar spine, femoral neck, total hip and forearm. If the T-score is more than -1.0 and less than -2.5 SD, the patient has osteopenia.

The T-score compares the patient to a healthy 30 year-old person of the same gender and when possible, same ethnicity. For a patient with osteopenia, the risk of a low impact fracture would be less than that of a patient with osteoporosis, but greater than a patient with a normal BMD.

What tests to perform?

Laboratory testing

If the Z-score is within 1 SD of age-matched controls, an extensive laboratory analysis is not indicated. It is often helpful to check a 25 vitamin D level and an intact PTH/calcium to ensure the patient is getting enough calcium and vitamin D.

An intact urine NTX or serum CTX can help in the assessment of bone resorption and may be useful when there is question about the benefit of beginning pharmacologic therapy. If the urine NTX is greater than 30 NM BCE/MM creatinine, or the serum CTX is greater than 300, it is expected that the BMD will worsen, unless pharmacologic therapy is started. For patients with a Z-score more than 1 SD below age-matched controls, more extensive laboratory testing can be ordered to help ascertain why the bone density is lower than expected.

FRAX

For patients with osteopenia, the Fracture Risk Assessment Tool (FRAX) can be very helpful. The FRAX was designed by a consensus group organized by the World Health Organization (https://www.sheffield.ac.uk/FRAX/). It calculates the overall risk of fracture and the risk of hip fracture over the next 10 years, if treatment is not instituted.

To calculate FRAX, the clinician must enter the following data into the software program: height, weight, gender, age, personal history of fracture, parental history of fracture, current use of glucocorticoids, history of rheumatoid arthritis, use of three or more alcoholic beverages/day, secondary causes of osteoporosis and femoral neck BMD.

In the United States, if the risk of overall fracture is 20% or greater and the risk of hip fracture is 3% or greater, it is felt that the patient would benefit from pharmacologic therapy. The threshold to treat varies in different countries due to variances in absolute risk. This is accounted for in the FRAZ instrument.

Vertebral fracture assessment

If the patient has kyphosis or has lost more than 2 inches in height, a Vertebral Fracture Assessment (VFA) can be done at the time of the DEXA. The VFA assesses whether the patient has suffered a vertebral fracture. Only half of vertebral fractures are symptomatic, so a patient can have had a vertebral fracture and be unaware of that information.

Biopsy

Bone biopsies are rarely needed in patients with osteopenia. One exception would be a patient who has suffered multiple low impact fractures and the bone density reveals only minimal bone loss. A bone biopsy is only considered when laboratory testing has been unrevealing. Bone biopsies may help diagnose possible collagen disorders.

Overall prognosis

For patients with osteopenia, their overall prognosis is often satisfactory, especially if the patient is assessed on a yearly basis for bone health.

There has been recent controversy about the needed frequency DEXA testing. Some argue that less frequent testing is indicated as the BMD changes very slowly over time. The patient should have overall bone health evaluated annually. If the patient is on a medication or has a comorbidity that affects bone health, DEXA testing should be done more frequently.

How should patients with osteopenia be managed?

If the FRAX suggests treatment is indicated, the clinician has several options. Oral bisphosphonates can be prescribed daily, weekly or monthly (alendronate, risedronate, ibandronate), parenteral bisphosphonates can be prescribed every 3 months (ibandronate) or yearly (zoledronic acid). These agents reduce the risk of new vertebral and nonvertebral fractures.

Raloxifene is a weaker antiresorptive agent and has only been shown to reduce the risk of vertebral fractures and not hip fractures. Two anabolic agents are FDA approved, Teriparatide and Abaloparatide, which reduce the risk of both vertebral and nonvertebral fractures. They are self-injectable medication given daily for 2 years.

After discontinuation these anabolic agents, an antiresorptive agent should be prescribed to help maintain the increase in BMD. Calcitonin is a very weak antiresorptive agent and probably does not reduce the risk of fracture to a significant degree.

Hormone replacement therapy (HRT) is associated with a reduction in both vertebral and nonvertebral fractures. If a woman chooses to take HRT, she is often being treated sufficiently, to prevent further bone loss. Due to the increased risk of cardiovascular disease and breast cancer, HRT is not first line therapy for bone health.

What happens to patients with osteopenia?

Patients with osteopenia should be evaluated yearly to assess bone health. A DEXA scan should be ordered every 1-3 years depending on the patient’s comorbidities, medications, activity level and pharmacologic therapies.

Laboratory testing including 25-vitamin D, intact PTH/Ca, and a urine NTX are often done yearly. This ensures that the patient is getting enough calcium and vitamin D. Although the Institute of Medicine made recent recommendations questioning the benefit of vitamin D levels over 20 ng/ml, most clinicians who treat bone disease favor 25 vitamin D levels of 32-50 ng/ml.

The urine NTX can be helpful in assessing for ongoing bone loss. If the NTX is above 30 NM BCE/MM creatinine, one can expect the BMD to decline if pharmacologic is not added. If the NTX is between 20-30 NM BCE/MM creatinine, the patient will probably have stability of BMD. If the NTX is less than 20 NM BCE/MM creatinine, the patient may have a low bone turnover state. If the patient is on antiresorptive therapy, consideration for discontinuation is recommended.

How to utilize team care?

If there is concern about the proper treatment of a patient with osteopenia, the patient can be referred to a physician who specializes in bone health. This is often a rheumatologist or an endocrinologist.

Nurse practitioners can play an important role in evaluating patients for bone health Programs can be set up to have the NP be the primary caregiver for the bone health of patients in a given practice and consult the supervising physician for difficult cases.

Dietitians can consult patients on the proper intake of calcium and vitamin D. The dietitian can help the patient understand how best to get calcium and vitamin D from diet and from supplements.

Physical therapists can teach patients a proper weight-bearing exercise program that can be done at home. Exercises that promote balance are particularly important.

Are there clinical practice guidelines to inform decision making?

For patients with osteopenia, the risk of fracture as determined by FRAX can be very helpful in deciding who will benefit from therapy.

The FRAX uses femoral neck BMD to determine risk of fracture. A patient could have a near normal hip BMD but low spine BMD. In this case the FRAX may not adequately assess the overall risk of fracture. The clinician can use FRAX as a guide, but may still choose to begin pharmacologic therapy in a patient with a low spine BMD, but near normal hip BMD.

Other considerations

ICD-10 Codes

• M85.80

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