SHM Converge Scientific Abstract ePoster Gallery-An Unusual Cause of Hypercalcemia

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A 40-year-old man with severe chronic tophaceous gout was found on routine labs to have significant hypercalcemia (13.7 mg/dL) and acute kidney injury (creatinine 4.2 mg/dL). On exam, he had extensive tophi and numerous subcutaneous nodules across the extremities, trunk, buttocks, and earlobes.<br /><br />Workup showed PTH-independent hypercalcemia: PTH was suppressed, and evaluation for malignancy and other common causes was negative. CT imaging ruled out solid tumors and granulomatous disease, and tests including SPEP, UPEP, PTHrP, and light chains were normal. Notable abnormalities included elevated ionized calcium and elevated 1,25-dihydroxy-vitamin D. X-rays of the hands and feet demonstrated extensive, partially calcified tophaceous gout with marked erosions and bone loss. Skin biopsy revealed calcified amorphous material surrounded by mononuclear histiocytes, giant cells, and fibrosis, consistent with a granulomatous reaction.<br /><br />The authors propose that large urate crystal deposits in tophi triggered macrophage-mediated granulomatous inflammation, leading to excess 1α-hydroxylase activity, increased 1,25-dihydroxy-vitamin D, and resulting hypercalcemia. This mechanism is similar to that seen in other granulomatous diseases such as sarcoidosis and tuberculosis, but is rare in gout.<br /><br />The patient improved with IV fluids and calcitonin, and prednisone was started to reduce peri-tophi inflammation. Outpatient pegloticase was planned. The case highlights that severe tophaceous gout, though uncommon, should be considered as a rare cause of PTH-independent hypercalcemia.

Asset Subtitle

Natalie A. Yass

Meta Tag

Author List Garrett Patrick, Morgan Hanrahan, Natalie A. Yass

Category Clinical Vignettes

Concept PTH-independent hypercalcemia

Concept Severe tophaceous gout

Concept Hypercalcemia

Concept Granulomatous Disease

Concept 1α-Hydroxylase

Concept 1a-Hydroxylase

Distinguished Non-Finalist

Presenter Organization Medical College of Wisconsin

Presenting Author Natalie A. Yass

Track Adult

Keywords

tophaceous gout

hypercalcemia

acute kidney injury

PTH-independent hypercalcemia

1,25-dihydroxy-vitamin D

granulomatous inflammation

urate crystal deposits

calcified tophi

calcitonin

prednisone

PTH-independent hypercalcemia

Severe tophaceous gout

Hypercalcemia

Granulomatous Disease

1α-Hydroxylase