How to rule out secondary causes of osteoporosis

Everyone diagnosed with osteoporosis deserves a laboratory assessment to rule out unsuspected secondary causes and a doozy of workup is recommended to primary physicians as “incredibly cost effective.”

With this workup it can identify 90 percent of abnormalities at a mean cost of $366 per diagnosis. That’s incredibly cost effective. You ‘re going to get a lot of information with actually not very much outlay at all as mentioned in a conference on internal medicine at the University of Colorado.

Applying this laboratory screening regimen to all patients diagnosed with osteoporosis is warranted because unsuspected secondary causes of the skeletal disease are so common. In various studies, laboratory screening has revealed a secondary cause in up to one-third of postmenopausal women with osteoporosis, in up to half of men, and in 50-80 percent of premenopausal osteoporosis patients according to a professor of internal medicine at the university.

The tests he advocates that primary care physicians order in all their patients with osteoporosis include a complete blood count, a complete metabolic panel, a 24-hour urine calcium/sodium/creatinine, a serum 25-hydroxyvitamin D level, and a serum phosphorus. In addition, men with osteoporosis should have their serum testosterone measured. A thyroid-stimulating hormone level should be obtained in patients who are taking thyroxine or if they look clinically hyperthyroid.

A measurement of parathyroid hormone is warranted as part of the screen in patients with an abnormal serum calcium. If the parathyroid hormone is normal, hyperparathyroidism can be ruled out.

Ordering a serum protein electrophoresis to check for multiple myeloma is appropriate in osteoporotic patients over age 50 years with an abnormal complete blood count.

This basic laboratory workup will identify patients with the relatively common secondary causes of low bone mineral density that account for 98 percent of all cases. These causes include vitamin D deficiency, malabsorption, hypogonadism, hypercalciuria, and myeloma. The two percent can be left for the rheumatologist to handle.

Special laboratory test were recommended to be left to bone disease specialist including bone turnover markers, a serum tryptase /urine, N-methylhistamine to screen for systemic mastocytosis, antitransglutaminase antibodies for celiac disease, a 24-hour urinary free cortisol and/or overnight dexamethasone suppression test to identify patients with Cushing syndrome and bone biopsy.

Who should be referred to a bone specialist for a more extensive workup? If somebody is losing bone or fracturing and they are on appropriate therapy and they are believed to be taking their medicine, that’s for sure somebody that must be seen by the bone specialist. Also a premenopausal women with the high Z score who has had a fracture that’s a typical. And patients with stage 4 or 5 chronic kidney disease; those are some of the toughest cases and are best referred to a bone expert.

On the other hand, if an osteoporotic patient simply can’t tolerate guideline-recommended initial therapy with an oral bisphosphonate such as alendronate (Fosamax)or risendronate (Actonel), there’s no need to bring in a specialist. Simply switch the patient to denosumab (Prolia), a monoclonal antibody against receptor activator of nuclear factor kappa-B ligand, administered by subcutaneous injection once every six months. The cost is about $2,200 per year, but the drug is covered by Medicare Part B. Clinical trial has demonstrated that denosumab boost bone mineral density by 6-9 percent, with an absolute 5 percent reduction in fractures and a 40-68 percent relative risk reduction.