Zoledronic acid in the treatment of secondary osteoporosis due to homocystinuria

We present a case of a 22-year-old woman admitted to our hospital because of low back pain. The patient, with a history of homocystinuria, inherited autosomal recessive amino acid metabolism disorder characterized by abnormalities of the eye, central nervous system, cardiovascular system, skeleton, and connective tissue.
The vertebral fracture assessment (VFA) by dual X-ray absorptiometry (DXA) detected multilevel (T4-L4) thoracic and lumbar spinal fractures. Both lumbar spine (L1-L4) and total body bone densitometry revealed significantly lower bone mineral density than expected for sex and age. The patient received treatment with zoledronic acid (Aclasta), a bisphosphonate applied in a once-yearly intravenous infusion. We did not observe any adverse effects and the patient still remains in follow-up study.
Osteoporosis associated with homocystinuria is one of the clinical manifestations of the disease. Bone tissue metabolism, bone mineral density and spinal cord structural changes monitoring, using VFA by DXA, during therapy with bisphosphonates may play an important role in evaluation of effects of administered treatment.