Gastroenterology

Congenital sodium diarrhoea caused by rare de novo activating guanylate cyclase mutation

“…Analysis of output from ileostomy demonstrated secretary diarrhoea with large volume of watery stool with osmotic gap of <50 mOsm/kg (stool osmotic gap <50 mOsm/kg indicates secretary diarrhoea and stool osmotic gap ≥100 mOsm/kg indicates osmotic diarrhoea)7 even during fasting and normalisation of serum Na with electrolyte replacement. The high stool sodium (130–140 mmol/L, normal reference value 30 mmol/L), stool chloride (>110 mmol/L, normal reference value 10–20 mmol/L)8 and low stool potassium (3 mmol/L, normal reference value 75 mmol/L) along with alkaline stool pH of 8 and metabolic acidosis confirmed that the secretary diarrhoea was due to CSD rather than chloride diarrhoea.…”

“…Daily stool volume and weekly serum and stool electrolyte evaluations were done throughout the hospital course (figure 4). He had an average stool output of 120 mL/kg/day (stool output of >10 g/kg/day is considered as diarrhoea)7 with Na requirement of 21 mEq/kg/day from both TPN and replacement fluid. He developed TPN-induced cholestasis, which resolved after treatment with ursodeoxycholic acid, phenobarbital and cycled fish oil-based lipid (Omegaven).…”