Rennies, Crohn's disease and severe hypercalcaemia

Area of Science:

• Gastroenterology
• Endocrinology
• Nephrology

Background:

• Milk-alkali syndrome is a rare condition caused by excessive intake of calcium and alkali, leading to hypercalcaemia and renal impairment.
• Crohn's disease is a chronic inflammatory bowel disease that can affect any part of the gastrointestinal tract.

Observation:

• A 59-year-old female presented with severe hypercalcaemia (5.2 mmol/l) and renal failure, alongside gastrointestinal symptoms.
• Initial suspicion of milk-alkali syndrome due to high calcium carbonate antacid use was considered.
• Persistent symptoms post-resolution of hypercalcaemia prompted further investigation.

Findings:

• Undiagnosed rectal Crohn's disease was identified as the underlying condition.
• Markedly elevated serum 1,25-dihydroxyvitamin D (calcitriol) levels were observed.
• The elevated calcitriol from Crohn's tissue is hypothesized to have enhanced intestinal calcium absorption from antacids, precipitating hypercalcaemia.

Implications:

• This case highlights a potential interaction between Crohn's disease, elevated calcitriol, and calcium antacid use in causing severe hypercalcaemia.
• It underscores the importance of considering underlying inflammatory conditions in patients with unexplained hypercalcaemia, even with apparent milk-alkali syndrome.
• Further research may elucidate the precise mechanisms linking Crohn's disease activity, vitamin D metabolism, and calcium homeostasis.