Abstract #1502833: Dilemma Identifying Pseudohypercalcemia

Hypercalcemia has a variety of potential causes with most common been primary hyperparathyroidism and malignancy accounting 90% cases. Other less hypercalcemia such as superimposed pseudohypercalcemia in the presence increased serum total calcium concentration but normal ionized level. We report evaluation for known history monoclonal gammopathy. case 71-year-old Caucasian male interstitial lung disease, cold agglutinin gammopathy diagnosed 2015 electrophoresis showed two M-protein at 0.33 0.16gm, admitted COVID positive, found hypercalcemia. Review systems was pertinent chronic fatigue lower extremity weakness. In medication prednisone 20mg daily one week prior to presentation. Examination limited due positive status. Laboratory Calcium Serum 10.6mg/dl, Albumin 2.3mg/dl corrected 12mg/dl (Previous Corrected 10.5mg/dl), PTH 83.4pg/ml (NR10-65pg/ml), Vitamin D 25-0H 46.2ng/ml (NR 30-100ng/ml), Vit 1-25 OH 47.8pg/ml 20-82pg/ml), Ionized 5.2mg/dL 4.5-5.3mg/dl), TSH 0.9uIU/ml 0.35-5.5uIU/ml), cortisol 19.6 mcg/dL 0-20 mcg/dL) IgM 1,690mg/dl 40-230mg/dL). The patient given IV pamidronate 60mg by medicine service. Normal while elevated excess well setting; reported cause false result. can be puzzling diagnosis. Pseudohypercalcemia clinical setting disorder unusual binding paraprotein release bone action parathyroid hormone interfering biochemical laboratory measurements. Clinicians should recognize abnormality levels differentiated measurement direct appropriate therapy etiology.