Hypercalcemia: It's Only Skin Deep

Introduction: Hypercalcemia is a common electrolyte abnormality with multi-systemic consequences that has been associated with several etiologies including genetic conditions, various pathologies, and certain medications. Dialysis patients usually experience hypercalcemia because of hyperparathyroidism and its treatment. Here, we present a dialysis patient with parathyroid hormone (PTH)-independent hypercalcemia resulting from psoriasis treatment. Case Description: A 43-year-old man with end-stage renal disease (ESRD) treated by home hemodialysis, and severe psoriasis presented to his home dialysis clinic with labs demonstrating up-trending monthly calcium levels between 10.7 mg/dL to 11.6 mg/dL (normal range: 8.5 – 10.5mg/dL). Corresponding PTH levels were down-trending from 699 pg/mL to 77 pg/mL (normal range: 16 – 80 pg/mL). Home medications as documented in multiple electronic medical record systems (EMR) were notable for calcitriol 0.25mg three time weekly and cholecalciferol 2000units daily - both of which were discontinued. The patient reported no significant intake of calcium supplements. Paraprotein studies were unremarkable. 25-OH and 1,25 dihydroxy vitamin D were 34.2 ng/mL (normal range: 30.0 - 100.0 ng/mL) and 118 pg/mL (normal range: 19.9 - 79.3 pg/mL) respectively. Imaging was negative for adenopathy, masses or infiltrates. Angiotensin converting enzyme was normal at 82 units/L (16 - 85 units/L). Upon further review, the patient reported seeing his dermatologist several months prior to the onset of hypercalcemia for psoriasis and received a prescription for calcipotriene cream, which he was applying liberally. Calcipotriene cream was discontinued and hypercalcemia resolved while PTH increased to 560 pg/mL. Discussion: There are only several reports illustrating the association of hypercalcemia with calcipotriene. Calcipotriene is a topical vitamin D analog that is a cornerstone therapy for psoriasis. Cutaneous absorption can result in excessive 1,25 dihydroxy vitamin D, thereby creating a PTH-independent mechanism for hypercalcemia. This case exemplifies a pitfall of EMR medication lists if medications are not uploaded or reviewed during visits. Topical agents, drops, over the counter medications, and herbal supplements may be particularly prone to this problem. In this case, there was considerable diagnostic delay and prolonged exposure to hypercalcemia related to incomplete EMR medication list.