Calciphylaxis (also known as calcific uremic arteriolopathy) is a serious disorder characterized by skin necrosis secondary to reduction in the blood flow caused by calcification, fibrosis, and thrombus formation in the dermohypodermic arterioles. While calcific uremic arteriolopathy has been reported in nonuremic patients, it is primarily observed in patients with end-stage renal disease, especially those with longstanding and often poorly controlled hyperphosphatemia, secondary hyperparathyroidism, and longer dialysis vintage. Due to the established tight connection between calciphylaxis and end-stage renal disease, it is common for physicians providing care for patients with end-stage renal disease to limit their differential diagnosis to kidney-related parameters.
A 72-year-old Caucasian woman with a history of stage 5 chronic kidney disease and uremic symptoms was admitted for elective initiation of hemodialysis. Physical examination revealed large eschars on medial thighs with mild erythema and extremely painful subsurface nodularity that had appeared 2 weeks prior to admission (FigureA and B). She had received antibiotics for presumed cellulitis without noticeable improvement. Laboratory studies were remarkable for an estimated glomerular filtration rate of 12 mL/min, albumin 2.9 g/dL (3.5-5.2), phosphate 7.7 mg/dL (2.5-5), and a parathyroid hormone level of 984 pg/mL (10-65). The clinical presentation of the lesions was highly suggestive of calciphylaxis; further workup revealed abundant diffuse vascular and soft tissue calcifications on plain x-ray of the thighs (Figure A and B; Inset), further supporting the diagnosis. Based on the typical clinical manifestations and radiologic findings of calcific uremic arteriolopathy, the decision was made not to perform a skin biopsy. However, presence of high normal serum calcium level (corrected calcium 10.2 mg/dL [8.4-10.2]) associated with disproportionately high levels of parathyroid hormone prompted further investigation; interestingly, parathyroid scintigraphy uncovered the presence of a metabolically active adenoma as the primary source of mineral derangements (Figure C). In addition to intensification of her phosphate-lowering therapy, intravenous sodium thiosulfate was initiated. The patient declined surgical parathyroidectomy.
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-Abhilash Koratala, MD, Amir Kazory, MD
This article originally appeared in the February issue of The American Journal of Medicine.
