Neurofibromatosis 1-related osteopenia often progresses to osteoporosis in 12 years.

ABSTRACT

The current study is based on our earlier investigation carried out in 1999, where bone mineral density (BMD) of 35 neurofibromatosis type 1 (NF1) patients was measured and osteoporosis was shown to be common in NF1. The findings have been confirmed by a number of later publications. The purpose of the current longitudinal study was to assess the bone health of these 35 NF1 patients 12 years after the initial study. A total of 28 patients were reached, and BMD of 19 patients was subsequently remeasured. Fracture history of 28/35 NF1 patients who were reached was verified from the medical records. Six NF1 patients had osteoporosis in 1999, and three of them had an osteoporotic fracture between 1999 and 2011, showing an increased fracture risk compared to NF1 patients without osteoporosis. BMD of 19 patients was remeasured in 2011, and four patients who had osteopenia in 1999 had osteoporosis in 2011. The decrease in BMD was not explained by changes in smoking habits, physical activity, sunlight exposure, body mass index, or laboratory parameters, even though secondary hyperparathyroidism was common. Osteoporosis was found in 2011 in patients aged 37 years or older, both men and women. The results showed that NF1-related osteopenia often progresses to osteoporosis since BMD decreases with aging even in young patients. Even though our sample size was 19 patients, we recommend follow-up of NF1 patients with osteopenia and consideration of prophylactic measures to prevent osteoporosis and associated fracture risk.