DOI: https://doi.org/10.36347/sjmcr.2026.v14i09.020

Pages: 2039-2043

Background: Severe hypercalcemia may cause neuropsychiatric manifestations, acute kidney injury, and characteristic electrocardiographic (ECG) abnormalities. In older adults, these findings may mimic acute coronary syndromes or primary rhythm disorders, resulting in diagnostic delay. Case presentation: An 82-year-old woman with cardiovascular risk factors and chronic vitamin D supplementation presented with a 10-day history of agitation and behavioral change, without chest pain, syncope, or dyspnea. After an initial emergency department discharge, persistent symptoms led to re-evaluation where modest troponin elevation and abnormal ECG findings were detected. On admission, she was confused but hemodynamically stable. The ECG demonstrated an irregular non-sinus rhythm with concave ST-segment depression and a markedly shortened corrected QT interval, followed by atrioventricular dissociation with retrograde atrial activation and persistent short QT. Laboratory testing revealed severe hypercalcemia with acute kidney injury and inflammatory markers elevation. Transthoracic echocardiography showed preserved biventricular function without segmental wall motion abnormalities and a small pericardial effusion. The patient underwent intensive intravenous hydration and urgent hemodialysis because of symptomatic severe hypercalcemia with renal dysfunction. Following calcium reduction, the ECG normalized with restoration of sinus rhythm and QT interval lengthening. Etiological workup demonstrated suppressed parathyroid hormone, normal thyroid function, and imaging findings suggestive of malignancy (heterogeneous splenomegaly with multiple masses, adrenal lesions, and osteolytic bone lesions), with further investigations establishing the diagnosis of multiple myeloma as the underlying cause of hypercalcemia. Conclusion: Hypercalcemia can produce dynamic ECG abnormalities that simulate ischemia or intrinsic conduction disease. Recognizing short QT interval and the reversibility of