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Pancreatitis Hypocalcaemia Saponification — ESENeph MCQ

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ModerateElectrolyte DisordersPancreatitis Hypocalcaemia SaponificationESENeph

A 55-year-old woman with CKD G4 develops acute pancreatitis. Her calcium drops to 1.6 mmol/L. Her PTH rises appropriately to 25 pmol/L. Her phosphate is low (0.6 mmol/L). What explains the hypocalcaemia in pancreatitis?

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Correct answer: D — Calcium sequestration by saponification (calcium soaps formed by fat necrosis in the retroperitoneum); also reduced PTH responsiveness from hypomagnesaemia and systemic inflammation

Hypocalcaemia in pancreatitis has multiple mechanisms: (1) saponification – free fatty acids released from pancreatic lipase-mediated fat necrosis chelate calcium, forming insoluble calcium soaps (the dominant mechanism); (2) hypomagnesaemia (common in pancreatitis from vomiting, poor intake, and GI losses) impairs PTH secretion and action; (3) systemic inflammation reduces bone responsiveness to PTH; (4) in CKD, the ability to generate 1,25-dihydroxyvitamin D in response to PTH is already impaired. The low phosphate (from poor intake and malabsorption) distinguishes this from CKD-MBD where phosphate is typically elevated.

Reference: NICE NG104 2018 – Pancreatitis; Fong and Khan 2012 – Hypocalcaemia Review