Calcific Uremic Arteriolopathy: An Underrecognized EntityCorridor Consult Spring 2011 - Volume 15 Number 2 https://doi.org/10.7812/TPP/10-114AbstractCalcific uremic arteriolopathy (CUA), or calciphylaxis, is an uncommon and underrecognized disease that often occurs in the setting of chronic kidney disease or end-stage renal disease. It is characterized by small-vessel calcification, although many times it is associated with normal serum levels of calcium, phosphorus, and parathyroid hormone. The lesions appear as necrotic eschars, ulcerations, indurated nodules, and dry gangrene and are usually very painful. Diagnosis is based on clinical judgment and recognition of characteristic skin lesions. Biopsy can be performed but may be complicated by poor wound healing. Treatment of CUA involves rigorous wound care, strict control of mineral metabolism with avoidance of calcium and vitamin D analogs, and pain control. Other treatment options include sodium thiosulfate, hyperbaric oxygen therapy, daily hemodialysis using low-calcium dialysate, and bisphosphonates. Even with treatment, CUA is associated with significant morbidity and mortality. The patient in the case reported here had characteristic skin lesions and several risk factors for CUA, but diagnosis was delayed. Case PresentationA Vietnamese woman, age 67 years, with end-stage renal disease (ESRD) due to systemic lupus erythematosus currently receives short daily home hemodialysis (SDHD), using the NxStage system one machine (NxStage Medical, Inc, Lawrence, MA, USA) with the assistance of her husband. She uses a right internal jugular (RIJ) tunneled catheter because of a previous rupture of an arteriovenous fistula, complicated by a three-week stay in an intensive care unit. Her other medical problems include hypertension, pancytopenia (related to systemic lupus erythematosus), secondary hyperparathyroidism, hyperlipidemia, and asthma. At the time of transfer, the patient's chest wall had a large area of eschar over the right side, with surrounding erythema and purulent drainage. Because of severe pain, the patient could not move her right arm. She was treated with intravenous clindamycin and vancomycin and oral ciprofloxacin. Repeat blood and wound cultures were obtained and the General Surgery Department was consulted for possible wound débridement. Hydromorphone was prescribed for pain control. BackgroundCUA is a rare condition characterized by small-vessel calcification, thrombosis, and skin and soft-tissue necrosis.1 The condition occurs primarily in patients with ESRD but has also been described in patients without chronic kidney disease.2 Reported risk factors for CUA are listed in Table 1. The pathogenesis of CUA is complex, however, and many times CUA is associated with normal serum levels of calcium, phosphorus, and parathyroid hormone. Recent evidence suggests that vascular calcification is not a passive process of mineral deposition but rather an active cell-mediated process resembling osteogenesis.3 Much of the current knowledge regarding CUA is based on small retrospective case series and reports. Conflicting reports, especially regarding risk factors for CUA, are common. CUA remains poorly understood and is associated with high morbidity and mortality. DiagnosisCUA should be considered when at-risk patients (especially those with ESRD) develop characteristic skin lesions. The lesions appear as necrotic eschars, ulcerations, indurated nodules, and dry gangrene and are usually very painful.4 Lesions occur frequently in the lower extremities,1 particularly the distal portion,5 but have also been described on the abdomen,6 the penis,7 the breast,8 and the upper extremities.9 Lesions may occur after skin trauma. Diagnosis can be confirmed by biopsy of a suspicious area; however, poor wound healing and infection may occur after the procedure. A bone scan can aid in the diagnosis of CUA and can be used to assess response to treatment during follow-up care.10 TreatmentTreatment of CUA involves rigorous wound care,5 strict control of mineral metabolism with avoidance of calcium and vitamin D analogs,11 adequate dialysis using low-calcium dialysate, and pain control. Sodium thiosulfate, an antioxidant and cation chelator, has been successfully used, according to several reports.12–14 Parathyroidectomy has been advocated by some researchers for wound healing,15 but others suggest that surgery is ineffective and does not prolong survival.16 Newer agents, such as cinacalcet, have been used to suppress parathyroid hormone, either alone or in combination with paracalcitol.17,18 Bisphosphonates have also been used to suppress osteogenesis in CUA.19 Though not widely available, hyperbaric oxygen chambers have been used with some success to treat CUA.20 Case OutcomeWhen CUA was suspected in our patient, calcitriol was immediately discontinued, and she was given low-calcium dialysate (2.0 mEq/L). Even after these measures, her serum calcium level became elevated during hospitalization, probably due to immobilization. Sodium thiosulfate 25% (25 g) was administered daily as an intravenous infusion. A culture obtained from the patient's chest wound grew Pseudomonas aeruginosa, which was treated with oral ciprofloxacin for a total of three weeks. ConclusionOur case underscores the need to consider the diagnosis of CUA in patients at high risk. CUA was not initially considered in our patient, probably because the inciting event was bleeding after catheter replacement, and thus the wound was assumed to be a complication of bleeding. The diagnosis of CUA should always be considered when characteristic skin lesions present in a patient who receives dialysis. Diagnosis may be more difficult in the patient without evidence of chronic kidney disease, but if other risk factors are present in conjunction with painful skin lesions, the clinician should always consider the diagnosis of CUA. Although CUA is associated with high morbidity and mortality, early recognition of the disease and a multifaceted approach to treatment may aid in recovery. Disclosure StatementThe author(s) have no conflicts of interest to disclose. AcknowledgmentKatharine O'Moore-Klopf, ELS, of KOK Edit provided editorial assistance. References1. Coates T, Kirkland GS, Dymock RB, et al. Cutaneous necrosis from calcific uremic arteriolopathy. Am J Kidney Dis 1998 Sep;32(3):384–91.
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