Authors: Domenico Rendina Gianpaolo De Filippo Libuse Tauchmanovà Luigi Insabato Riccardo Muscariello Fernando Gianfrancesco Teresa Esposito Michele Cioffi Annamaria Colao Pasquale Strazzullo Giuseppe Mossetti
Publish Date: 2009/09/10
Volume: 85, Issue: 4, Pages: 293-300
Abstract
To evaluate serum levels of osteoprotegerin OPG soluble receptor activator of the nuclear factorκB RANKL and their relationship with FGF23 lumbar bone mineral density BMD and bone turnover markers five patients with tumorinduced osteomalacia TIO and 40 healthy controls were studied TIO patients were followed for 360 days after surgical removal of underlying tumor n = 2 or beginning of therapy with phosphate and calcitriol when surgical treatment was impossible n = 3 At diagnosis TIO patients had higher levels of FGF23 and bonespecific alkaline phosphatase bALP and lower levels of cathepsin K CathK RANKL and RANKL/OPG ratio compared to controls During the followup FGF23 decreased significantly only in patients who underwent a surgical excision while phosphate and BMD increased in all patients The increases in BMD phosphate and renal phosphate reabsorption rate were directly related In the first 60 days of followup we observed a prolonged inhibition of RANKL CathK and bone resorption markers associated with a persistence of TIO symptoms and an increase in bALP From day 60 levels of bone turnover markers returned progressively within the normal range and a clinical remission was observed The inhibition of the RANKL/OPG pathway and the uncoupling of bone formation and resorption observed in patients with active TIO may be a compensatory mechanism attempting to reduce worsening of osteomalacia The BMD increase during TIO treatment is related to the improvement of phosphate rather than FGF23 levels A “hungry bone”like syndrome was observed after surgical or pharmacological treatment
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