Hypercalcemia secondary to leprosy

Despite the high prevalence of leprosy in undeveloped countries, hypercalcemia secondary to leprosy is rare. One of most important mechanisms responsible for this disorder seems to be high serum concentrations of 1,25-dihydroxyvitamin D produced extrarenally by the granulomatous tissue. Serum levels of parathyroid hormone-related protein (PTHrP) have never been analyzed in this disorder. We report here a case of hypercalcemia in a patient with leprosy. Serum levels of 1,25-dihydroxyvitamin D were normal in spite of low levels of 25-dihydroxyvitamin D and acute renal failure. Suppressed serum levels of parathyroid hormone and PTHrP were also remarkable. In this case, PTHrP seems not to play an important role in the pathogenesis of hypercalcemia. Our data indicate that this disorder may be due, at least in part, to abnormal calcitriol overproduction by granulomatous tissue. Further investigations of the prevalence and pathogenesis of this type of hypercalcemia are needed.