Bone mineral turnover in a patient with osteogenesis imperfecta estimated by fluoride excretion

A child with severe osteogenesis imperfecta was treated with NaF for 8 years, at the end of which time his iliac bone contained 29 mg F/g Ca. Urine F was assayed at intervals for 4.5 years after discontinuing treatment. After the first few days the decline in urinary F excretion can be described by a two component exponential function, with half-times of 5.4 months (10%) and 8.9 years (90%). The latter half-time value is of the same order of magnitude as those observed for F and other "bone-seeking" elements in normal subjects, which suggests that the turnover rate of bone mineral is normal in this disease. Three methods for estimating the attained body F burden at the end of NaF treatment--namely, metabolic balance, bone biopsy, and integration of the exponential function--yielded comparable values.