Hypocalcemia Secondary to Inadvertent Denosumab (Prolia) Administration in a 4‐Month‐Old Cat

OBJECTIVE: To describe the clinical presentation, diagnosis, and management of hypocalcemia secondary to inadvertent administration of denosumab in a 4-month-old kitten. CASE SUMMARY: A 4-month-old neutered female domestic shorthair kitten was presented with acute weakness, tremors, third eyelid prolapse, and ataxia for several hours. Physical examination revealed lethargy, tachycardia, hypothermia, mild dehydration, and apparent nausea. Neurologic findings included tremors, cerebellar ataxia, bilateral mydriasis, and decreased bilateral direct and indirect pupillary reflexes. ECG confirmed sinus tachycardia. Blood work showed severe ionized hypocalcemia (0.74 mmol/L [2.96 mg/dL]; reference interval [RI]: 1.10-1.40 [4.40-5.60]), mild hypokalemia (3.38 mmol/L [3.38 mEq/L]; RI: 3.90-4.90 [3.90-4.90]), and moderate hyperglycemia (10.8 mmol/L [194 mg/dL]; RI: 3.6-6.2 [64.86-111.71]). The owner later disclosed an accidental subcutaneous injection to the kitten with denosumab 1 week earlier, strongly suggesting drug-induced hypocalcemia. Treatment with IV calcium gluconate 10% (0.5 mL/kg over 10 min twice) resolved signs and normalized iCa (1.20 mmol/L [4.8 mg/dL]). Isotonic crystalloids with potassium and maropitant were given for hydration, electrolyte correction, and nausea. Oral calcium (60 mg/kg, q 24 h) was started on Day 1; iCa remained normal (1.26 mmol/L [5.04 mg/dL]) at Day 2, and the kitten was discharged. At Day 11, iCa was 1.19 mmol/L [4.76 mg/dL], the dose was halved, and at Day 18, iCa remained normal (1.24 mmol/L [4.96 mg/dL]), allowing for discontinuation of therapy. NEW OR UNIQUE INFORMATION PROVIDED: This report describes hypocalcemia secondary to inadvertent administration of denosumab to a kitten. The clinical manifestations and diagnosis are described, along with the details of management that led to the kitten in this report making a full recovery.