Confusion, Muscle Cramps and Trousseau’s Sign

🗒️ Question

A 60 year old man presents to the emergency department with a one week history of perioral numbness, muscle cramps and intermittent confusion. His past medical history includes CKD 4, for which he has been on conservative management. He has been non-compliant with his medications recently which include calcium supplements, phosphate binders and calcitriol. On examination, he appears anxious, mildly disorientated and has a positive Trousseau’s sign.

Blood results show the following:

• Serum calcium: 1.6 mmol/L (Normal: 2.2–2.6 mmol/L)

• Serum phosphate: 2.2 mmol/L (Normal: 0.8–1.5 mmol/L)

• Parathyroid hormone (PTH): 150 ng/L (Normal: 10–65 ng/L)

• Serum creatinine: 250 µmol/L (Normal: 60–120 µmol/L)

• eGFR: 25 mL/min/1.73m² (Normal: >90 mL/min/1.73m²)

Which of the following best explains his hypocalcaemia?

(A) Hypoalbuminaemia
(B) Hyperphosphataemia
(C) Hypomagnesaemia
(D) Vitamin D resistance
(E) Parathyroid hormone resistance