Environmental factors associated with nutritional secondary hyperparathyroidism in wild birds

Six published case reports of nutritional secondary hyperparathyroidism are described occurring in different species of juvenile wild birds worldwide. Gross skeletal deformities are characterised by fractures and curvature of the long bones and beak resulting from an altered calcium/phosphorus ratio in the blood. The histopathologic diagnosis is osteodystrophia fibrosa and parathyroid gland hyperplasia. Deficiency of vitamin D is implicated in the two instances in which this was measured. Environmental factors include: decreased biodiversity of food sources, surface water pollution, seasonal conditions affecting food and exposure to UV light, and sub-lethal exposure to xenobiotics. Evidence is presented on the possible role of xenobiotics in the pathogenesis.