Context.— The extrarenal synthesis of active vitamin D sterols has a central causative role in the hypercalcemia associated with various granulomatous diseases.
Objective.— To study the calcium metabolism in patients with cat-scratch disease who have hypercalcemia.
Design.— Case report.
Setting.— University hospital in Barcelona, Spain.
Patients.— Two identical twins who developed asymptomatic hypercalcemia during the acute phase of cat-scratch disease.
Main Outcome Measures.— Serial measures of calcium homeostasis and metabolism over a 2-month period.
Results.— On admission and 6 and 7 days later, both patients were found to have increased levels of serum and urinary calcium, serum phosphate, and serum 1,25-dihydroxyvitamin D [1,25(OH)2D], whereas they had normal values of serum 25-hydroxyvitamin D and urinary cyclic adenosine monophosphate and decreased serum concentrations of intact parathyroid hormone. Sixteen and 20 days after admission, these abnormalities had resolved without treatment. A direct correlation was observed between the serum 1,25(OH)2D levels and both the serum and 24-hour urinary calcium concentrations. Also, the concentrations of calcium and 1,25(OH)2D paralleled the clinical activity of the infectious disease over the period these parameters were measured.
Conclusions.— Our cases provide evidence that cat-scratch disease can produce hypercalcemia through the unregulated production of the metabolite 1,25(OH)2D. Cat-scratch disease should be added to the list of granuloma-forming diseases that are responsible for 1,25(OH)2D-mediated hypercalcemia.
