CHANGE IN BONE MINERAL DENSITY IN A PATIENT WITH OSTEOPOROSIS TAKING OVER THE COUNTER STRONTIUM CITRATE

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: SAT 199-223-Disorders of Bone & Calcium Homeostasis: Case Reports
Clinical
Saturday, June 15, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board SAT-221
Sidra Azim*, Amit Bhargava, Farheen Kassim Dojki and Faryal Sardar Mirza
University of Connecticut, Farmington, CT
Background: Strontium ranelate (SrR), used for the treatment of osteoporosis (OP) in Europe and Australia, is not FDA approved or available in United States (US). Here, strontium citrate (SrC) is available as a nutritional supplement. Data on effects of SrC on bone are lacking, but recently we are seeing an increase in its self administration by patients to treat OP “naturally.” We report changes in bone mineral density (BMD) in a patient using SrC.

Clinical Case: 72-year-old female with history of OP was treated with weekly alendronate for 10 years till 2006, when she was changed to an every other week regimen. Alendronate was stopped in 2007. Patient started self administrating SrC (680mg/day) in 2006 and continued to take calcium (600mg bid) and vitamin D (2000units/day). She remained physically active. Serum calcium and creatinine remained normal, and 25OH Vitamin D remained in the 32-66ng/ml range. Urine N-telopeptide (NTX) was monitored as a bone resorption marker (22-28 NTX units) and bone specific alkaline phosphatase (12-13.7mcg/L) as a bone formation marker. She continued SrC on her own till 2012, when she was advised to stop taking it due to concerns about accumulation. Total hip mean BMD increased 2.7% in the first 2 years, to a maximum of 9.2% in 6 years (1.53%/yr). Femoral neck mean BMD increased by 9% in 6 years (1.52%/yr). L2-L4 BMD increased by 30% in 6 years (5%/yr), which was difficult to interpret in view of degenerative changes.

Conclusion: There are no data available on the use of SrC to treat OP. SrR has been shown in vivo and in vitro to decrease bone resorption by inhibiting osteoclasts and stimulate bone formation by activating osteoblasts. Sr is a heavier element than calcium, and although less than 1% incorporates into bone, it can cause possible overestimation of BMD by 10%. We see a steady increase in our patient’s BMD. Whether it is due to a true increase or an increased attenuation of x-rays by Sr is not clear. One study assessing bone Sr levels after SrC use showed a 6-7x increase in bone Sr signal, but there was no analysis of a corresponding effect on BMD. Furthermore, whether the increase seen in BMD with SrC will translate into fracture risk reduction is not known. SrC is increasingly being used by patients for osteoporosis self treatment. Further studies are needed to delineate its effect on bone health, fracture reduction and its safety.

Nothing to Disclose: SA, AB, FKD, FSM

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