Phosphate enemas causing profound refractory hypocalcaemia: A case report.
Jennifer Nobes, Michael J Murphy
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Case in brief
A 37-year-old woman with alcohol-related liver disease was admitted with melaena and coffee-ground vomiting and developed severe hepatic encephalopathy. After phosphate enemas were given three times daily, her adjusted calcium fell to 0.85 mmol/L while phosphate rose to 6.4 mmol/L. The inverse changes suggested phosphate-related calcium sequestration, possibly following rectal phosphate absorption. The enemas were stopped, and serum phosphate returned to the reference range over 72 h. She required more than 70 mmol of intravenous calcium over 5 days; by Day 11, calcium, phosphate and sodium were within their reference ranges.
What made this case unusual
The profound, refractory hypocalcaemia was associated with phosphate enemas, with the authors proposing that phosphate was absorbed rectally rather than acting only through the intended colonic mechanism.
Diagnostic / clinical pearl
In a patient receiving phosphate enemas who develops marked hypocalcaemia, check phosphate and consider rectal phosphate absorption; the paired calcium and phosphate changes may help identify the cause.