There is no method of determining the actual structure of bones without actually removing a piece during a biopsy (which is not practical or necessary) Since routine x-rays cannot be diagnostic until very late stages of osteoporosis. . The diagnosis of osteoporosis is based on special x-ray methods called densitometry. Densitometry will give accurate and precise measurements of the amount of bone (not their actual quality). This measurement is termed "bone mineral density" or BMD.

Diagnostic Testing

The World Health Organization "WHO" has established criteria for making the diagnosis of osteoporosis, as well as determining levels, which predict higher chances of fractures. These criteria are based on comparing bone mineral density (BMD) in a particular patient with those of a 25-year-old female. BMD values which fall well below the average for the 25-year-old female (stated statistically as 2.5 standard deviations below the average or T score < -2.5) are diagnosed as "osteoporotic". If a patient has a BMD value less than the normal 25-year-old female, but not 2.5 standard deviations below the average (T score > -2.5 and < -1), the bone is said to be "osteopenic" (osteopenic means decreased bone mineral density, but not as severe as osteoporosis).   Interestingly, although these criteria are widely used, they were devised in a Caucasian female so there will be some differences when these levels are applied to non-Caucasian females or to males in general. Despite this flaw, measurement of BMD is used daily and has proven to be very helpful in all groups. Some men will be subject to increased fracture rates when they have significantly less BMD than the predicted fracture level for women.  In other words, some men will be at increased risk for fracture even when they have osteopenia.

At our Center we recommend a bone mineral density score to be done using a central DXA scan "dual energy x-ray absorptiometry “ to include hip and spine. We tell our patients to avoid having a peripheral DXA since they are really limited as a screening test and for diagnostic follow-up & monitoring treatment should not be used. We also tell all of our patients to be sure they get there DXA scan done at a center that they will be able to follow up in 24 month since repeat scans done on the same DXA are the most reliable for accurate interpretation and comparison.

In conjunction with the central DXA scan we also like to get another sometimes important piece of information that is a urine analysis for NTX, NTx is a collagen telopeptide marker which is formed during bone resorption and excreted in the urine. This bone resorption marker is clinically useful for detecting rapid bone loss which can result in low bone mineral density, osteoporosis, and  an increased susceptibility to fracture. Soon after starting antiresorptive therapy significant changes in baseline Ntx levels occur which can be monitored to determine therapies effectiveness. Unlike bone mineral density measurements, which give a static picture of a bone's density, the NTx measure assesses the rate of bone loss. Using this test we can evaluate to a certain degree the effectiveness of osteoporosis therapy since DXA scans take 18 months to 24 months to show change.

Bone Density Information Sheet (PDF file) according to the National Osteoporosis Society

LABORATORY TESTS

For an uncomplicated patient with osteoporosis, a lab workup would be:

• Chemistry Profile
• CBC
• Alkaline Phosphates
• TSH
• Males Should Have Testosterone Measured
• Urine NTX (Optional Used For Evaluation Of Therapy Effectiveness)

Gonadal hormones are very important causes of osteoporosis. In females whom are postmenopausal and using HRT in our center since we only use bio-identical estrogen (17 B estradiol) we feel it is extremely useful to measure serum estradiol levels. We target therapy to keep these levels over 80 ng/dl .  For our male patients, testosterone levels are also measured. We find a good number of men may have low testosterone without other clinical symptoms. If testosterone is low, then further work-up is needed.

SECONDARY OSTEOPOROSIS

In patients with abnormal serum calcium or with unusually severe bone disease or when the Z score from the DXA scan is <-2, Secondary causes of osteoporosis need to be evaluated and additional laboratory tests need to be considered depending on clinical information

• Vitamin D (25 OH)
• 24 Hour Urine For Calcium
• Parathyroid Hormone Levels (PTH)
• UPEP/SPEP
• ESR
• Celiac Disease Antibodies

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