A case of severe 1,25-dihydroxyvitamin D-mediated hypercalcemia due to a granulomatous disorder.
BACKGROUND
Profound hypercalcemia is usually due to underlying malignancy.


METHODS
We describe a case of granulomatous myositis presenting with extreme hypercalcemia of 20.1 mg/dl and generalized weakness that did not resolve despite rapid correction of serum calcium. The disease process was unmasked by cholecalciferol supplementation. Initial search for a malignant process yielded no diagnosis, but an elevated 1,25-dihydroxyvitamin D level, in the setting of a suppressed PTH and undetectable PTHrP, pointed to the presence of excessive 1α-hydroxylase activity.


RESULTS
Biopsy of the vastus lateralis muscle showed extensive granulomatous myositis. Immunohistochemical staining for 1α-hydroxylase was localized to the multinucleated giant cells and histiocytes. Musculoskeletal magnetic resonance imaging showed involvement of proximal muscle groups of both thighs and upper limbs.


CONCLUSIONS
Measurement of vitamin D metabolites is pivotal in diagnosing 1,25-dihydroxyvitamin D-mediated hypercalcemia. Granulomatous disease can occasionally cause profound hypercalcemia and needs to be considered in the differential diagnosis. 1,25-Dihydroxyvitamin D-mediated hypercalcemia is responsive to glucocorticoid therapy.
Department of Endocrinology and Metabolism, Concord Repatriation General Hospital, Concord, New South Wales 2137, Australia. janezhang2@gmail.com
Jane Tong Wen
JT
Zhang
Charles
C
Chan
Sun Young
SY
Kwun
Katherine Ann
KA
Benson
D000368:Aged; D005260:Female; D006099:Granuloma / Q000150:complications*; D006801:Humans; D006934:Hypercalcemia / Q000209:etiology* / Q000628:therapy; D009220:Myositis / Q000150:complications; D012507:Sarcoidosis / Q000150:complications; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000502:physiology
D014807:Vitamin D; C097949:1,25-dihydroxyvitamin D