The present invention relates to a method of treating metabolic bone diseases in a patient, which comprises the modulation of PEX activity to modulate the bone micro-environmental concentrations of critical bone anabolic agents, namely PTH and PTHrP. The present invention also provides the use Of inhibitors of PEX activity, such as, the use of inhibitors of NEP and/or ECE and/or PEX such as phosphoramidon, and analogs thereof, to modulate and preferably increase PTH/PTHrP levels in bone microenvironment to consequently result in an increase in bone formation, as confirmed by serum bone markers, namely, osteocalcin, to thereby provide a novel method for treating metabolic bone diseases, such as osteomalacia, osteoporosis, osteopetrosis, Paget's disease and X-linked hypophosphatemic rickets.