Recurrent lead poisoning in a child with immobilization osteoporosis.

Lead poisoning associated with progressive osteoporosis in patients who have been previously lead poisoned has been described but poorly documented. We managed a 4-year-old child with a prior history of plumbism who developed recurrent blood lead elevations (as high as 70 mcg/dl), requiring multiple courses of EDTA, after acute paraplegia from transverse myelitis. The patient was hospitalized throughout these periods of chelation. No exogenous sources of lead were found. Calcium, phosphate, magnesium, alkaline phosphatase and parathyroid hormone levels remained normal while vitamin D levels were depressed. Metabolic studies revealed negative calcium balance with an elevated urinary calcium:creatinine ratio. Long-bone radiographs were remarkable for progressive osteoporosis with no evidence of metallic foreign bodies. This case illustrates that bone, the major repository of lead, can become a source of significant lead level elevations in conditions associated with accelerated resorption.