Immobilization-induced hypercalcemia and regional osteoporosis.

Immobilization hypercalcemia accompanied by unusual hormonal and bony changes complicated the Guillain-Barré syndrome in a 21-year-old woman. Metaphyseal rarefaction appeared in many sites and was severe in the lower limbs. A bone scan showed increased uptake of 99mTc methylene diphosphonate at these sites and throughout the axial skeleton. The literature on experimental metaphyseal rarefaction suggests that osteoclastic resorption and enhanced regional blood flow are associated with immobilization. Suppression of this osteoclastic component of the increased bone turnover, especially if it is widespread, was the rationale for treatment with calcitonin (CT). The patient also became amenorrheic, with low plasma gonadotropin and estrogen levels. Estrogen therapy coincided with a return of plasma calcium to normal.