The Diagnosis of Osteoporosis
Osteoporosis is diagnosed by two criteria. The first is the occurrence of a fragility fracture in one of the major bones and the second is a DXA bone density test results with a T-score of –2.5 or less in the spine, hip or wrist.
Osteopenia is not a Disease
Osteopenia is a bone density range between normal and osteoporosis. I call it the “zero,” the “warning area,” or the “safe zone” depending on the context. When trying to explain what it is I will say that osteopenia is like the 0 on in a number series of +2 +1 0 –1 –2. You cannot go straight from +1 to –1. A zero was invented to occupy that place so we could work with imaginary numbers like –1. The other example was the clinical need to have a bone density that proceeded osteoporosis that people traveled through before becoming osteoporotic. That bone density area became osteopenia.
I call it the “warning area” when I want to get the attention of the patient who is loosing bone just how close they are to becoming osteoporotic. While it is semantics because risk for fracture is continuous, it is not linear. Fracture risk is an exponential variable whose inflexion point moves sharply upward around a T-score of –2.5. This means the fracture risk of someone at –2.75 is a whole lot higher than at –2.25 even though they are just 0.5 T-scores apart.
One the other hand, I call it the “safe zone” when discussing a patient’s successful response to treatment when their DXA bone density has risen progressively our of the “danger zone” into the “safe zone” and “technically” they no longer have osteoporosis, but they do because if they stop treatment they will fall back into the “danger zone”. We discuss that too but it is a time for rejoicing all the same.
Patients come to my clinic or are referred here because they have osteoporosis or are concerned the do and want confirmation. Some want a second opinion regarding their treatment options. We evaluate them.
Screening of Patient’s Bone Health with DXA Bone Densitometry
Practitioners who see their patient year in and year out may need a prompt for them to evaluate a freshly menopausal woman for osteoporosis with a DXA bone density test. Early menopause is the ideal time to evaluate the highest risk group, white women. Most white women carry the genetic osteoporosis complex that is triggered by the loss of estrogen characteristic of menopause. Bone density survey data show that 50% of white women entering menopause are osteopenic and 7% are osteoporotic. Bone loss rates increase at menopause from an average of 0.5% annually in the 40s to 1-2% per annum during the 50s. All our US FDA indicated drugs shown to be safe and effective for treating osteoporosis and preventing fractures are designed for use by postmenopausal women, not women before menopause. Since white women experience 2.5 x more fractures from osteoporosis than any other human subtype, logic dictates that a screening recommendation like this should focus on them. Other women and men can also be screened on a case-by-case basis but it is not economically justified or medically necessary in my view as a routine practice. Screening DXA is indicated when everyone turns 60 years old. White women are a special case for the reasons mentioned and for the reasons mentioned. I suggest primary care practitioners make it a standing practice to do a screening DXA bone density test on each of them once soon after menopause in order to characterize their current bone health state and be empowered with data now to plan what the next best step to take.
An Approach to Patients with Low Bone Density and Osteoporosis on DXA
When the DXA test shows a T score of less than –2 at the spine or hip that is low bone density and if the T score is less than –2 at the spine or hip that is osteoporosis. A number of diseases present with low bone density with osteoporosis being the most common but a rookie error in diagnostic medicine is to accept the most frequent cause of a condition as its diagnosis without looking further to confirm it.
Osteomalacia, multiple myeloma, Cushing disease and primary hyperparathyroidism all cause osteoporosis and can present with low bone density and/or osteoporosis. Some of these will even respond to standard treatment for osteoporosis but the responses will the poor at best and disastrous at worse. When the diagnosis and treatment of these people based on the patient’s history, physical exam, and abnormal DXA alone, the diagnosis has not been confirmed in the laboratory. In this case, if the practitioner has diagnosed “typical” Postmenopausal Osteoporosis, PMO in white women and will be correct the majority of the time. Testing should still be done even when there is little doubt in anyone’s mind regarding the validity of the diagnosis because studies show 20% of the time there will be another cause for bone loss in addition to PMO present. The basic laboratory evaluation I use is designed to efficiently and cost effectively excludes the most common and likely secondary causes of osteoporosis.
All osteoporosis consultations conducted here begin with a thorough review of the patient’s medical and surgical history, their medication use, their family history and use of alcohol and tobacco. Diet and exercise practices are very important to understand and if needed help the patient optimize for them to get the greatest benefit from treatment.
A complete physical exam is performed to look for signs of medical causes of osteoporosis and to best assess the patient’s medical health and fitness. The exam should be disease specific with special attention to the spine, joints, patient’s mobility, exercise potential, balance and fall risk.
After DXA, history, and physical are complete a diagnosis is rendered and a laboratory evaluation is planned.
The patient is referred to the lab for basic osteoporosis laboratory evaluation. They are placed on a preliminary treatment based on the results available. This might include recommendations for diet, exercise, and supplements. Drug therapy might be recommended at that time of withheld until the results of the evaluation are complete.
Our practice is to give the patient a follow up appointment to discuss their lab work and if placed on medication for osteoporosis to see how they are doing on it. After the patient is given their appointment usually for 1 month, that ends the visit and the first part of the evaluation.
Over the next week or two, the lab results will come in and be reviewed, when the patient returns to the office to go over her results we are ready to discuss them and discuss together what to do next. This concludes the initial evaluation.