Recovery from skeletal fluorosis (an enigmatic, American case)

Abstract

A 52-year-old man presented with severe neck immobility and radiographic osteosclerosis. Elevated fluoride levels in serum, urine, and iliac crest bone revealed skeletal fluorosis. Nearly a decade of detailed follow-up documented considerable correction of the disorder after removal of the putative source of fluoride (toothpaste).

Introduction: Skeletal fluorosis, a crippling bone disorder, is rare in the United States, but affects millions worldwide. There are no data regarding its reversibility.

Materials and methods: A white man presented in 1996 with neck immobility and worsening joint pains of 7-year duration. Radiographs revealed axial osteosclerosis. Bone markers were distinctly elevated. DXA of lumbar spine (LS), femoral neck (FN), and distal one-third radius showed Z scores of +14.3, +6.6, and -0.6, respectively. Transiliac crest biopsy revealed cancellous volume 4.5 times the reference mean, cortical width 3.2 times the reference mean, osteoid thickness 25 times the reference mean, and wide and diffuse tetracycline uptake documenting osteomalacia. Fluoride (F) was elevated in serum (0.34 and 0.29 mg/liter [reference range: <0.20]), urine (26 mg/liter [reference range: 0.2-1.1 mg/liter]), and iliac crest (1.8% [reference range: <0.1%]). Tap and bottled water were negative for F. Surreptitious ingestion of toothpaste was the most plausible F source.

Results: Monitoring for a decade showed that within 3 months of removal of F toothpaste, urine F dropped from 26 to 16 mg/liter (reference range: 0.2-1.1 mg/liter), to 3.9 at 14 months, and was normal (1.2 mg/liter) after 9 years. Serum F normalized within 8 months. Markers corrected by 14 months. Serum creatinine increased gradually from 1.0 (1997) to 1.3 mg/dl (2006; reference range: 0.5-1.4 mg/dl). Radiographs, after 9 years, showed decreased sclerosis of trabeculae and some decrease of sacrospinous ligament ossification. DXA, after 9 years, revealed 23.6% and 15.1% reduction in LS and FN BMD with Z scores of +9.3 and +4.8, respectively. Iliac crest, after 8.5 years, had normal osteoid surface and thickness with distinct double labels. Bone F, after 8.5 years, was 1.15% (reference range, <0.1), which was a 36% reduction (still 10 times the reference value). All arthralgias resolved within 2 years, and he never fractured, but new-onset nephrolithiasis occurred within 9 months and became a chronic problem.

Conclusions: With removal of F exposure, skeletal fluorosis is reversible, but likely impacts for decades. Patients should be monitored for impending nephrolithiasis.