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Congenital Sodium Diarrhoea (CSD) is a rare, genetical form of intractable diarrhoea with high faecal sodium loss. Symptoms start in utero; life-threatening dehydration, electrolyte abnormalities and metabolic acidosis occur if untreated. Syndromic CSD caused by SPINT2 1 mutations is associated with choanal/intestinal atresias, corneal erosions and tufting enteropathy. We present three male infant Kuwaiti cousins with syndromic CSD and variable clinical presentation.Case 1 born at term, birth weight (BW) 3.6 kg, presented with diarrhoea and severe dehydration on day 20. Pregnancy was uneventful (absent polyhydramnios). On transfer at 11 months he was on minimal enteral feeds, suboptimal parenteral nutrition (PN) and severely malnourished (3.9 kg, z-7.68)). Urine sodium was low (< 5 mmol/L), faecal sodium high (113 mmol/L). Diarrhoea continued when fasting. OGD revealed duodenitis with tufting-like changes of surface enterocytes (EpCAM retained). Genetic testing revealed a homozygous SPINT2 gene variant, confirming CSD. After stabilization with PN and correction of fluid/electrolyte abnormalities he achieved slow catch-up growth (6.84 Kg, -4.10) and was repatriated on PN (160 ml/Kg, sodium 10 mmol/Kg) with minimal oral diet aged 16 months.Case 2 born at term (BW 3 kg), passed meconium, had formed stools initially but presented dehydrated with diarrhoea on day 10 following uneventful pregnancy (no polyhydramnios). On transfer aged 3 months his weight had dropped to 2.85 kg (z- 5.00). PN was started; feeds temporarily discontinued. Diarrhoea continued. Stool sodium was high (127 mmol/ml). OGD demonstrated tufting enteropathy (EpCAM preserved). Genetic testing is pending but SPINT2 mutation likely; CSD diagnosed clinically. At present he is 10 months old with good weight gain (8.47 kg, 25th centile). He remains on PN (210 ml/Kg, sodium 18 mmol/Kg) awaiting home PN.Case 3 born prematurely (32/40), BW 1.8 kg (50th centile corrected, z= 0.00), antenatal polyhydramnios, developed diarrhoea soon after birth, which continued when fasted. PN was started (severe dehydration, electrolyte disturbance). Choanal atresia was repaired in the first week. Genetic testing identified a homozygous missense variant in SPINT 2 gene confirming CSD. When transferred he was malnourished (2.35 Kg, z- 7/16). PN fluids + electrolytes were optimised (120 ml/Kg, sodium 10 mmol/l), macronutrients gradually increased (high refeeding risk) and stool losses replaced ml for ml with 0.9% NaCl + KCL 10 mmol/500 ml (stool sodium 120 mmol/L). Endoscopic assessment is pending.Each case had similar dysmorphic features but no eye problems.Syndromic CSD is clinically heterogeneous. Only 1/3 in our series had antenatal polyhydramnios, presented with severe diarrhoea on day 1 of life and had choanal atresia. 2/3 cases developed diarrhoea later (day 10 and day 20 respectively), although this may not be accurate as stool may have been mistaken for urine.Early initiation of PN and replacement of fluid and electrolyte losses is essential to avoid malnutrition and life-threatening fluid/electrolyte imbalance. Antenatal polyhydramnios and/or bowel dilatation is not always seen. Clinical suspicion after birth should be high. A stool sample for electrolytes can be easily obtained though insertion of a small-bore nasogastric tube into the rectum to differentiate urine from sodium rich stool.2 References Salomon J, Goulet O, Canioni D, et al. Genetic characterization of congenital tufting enteropathy: epcam associated phenotype and involvement of SPINT2 in the syndromic form. Hum Genet. 2014 Mar;133(3):299–310.Köglmeier J, Lindley KJ. Congenital diarrhoeas and enteropathies. Nutrients 2024 Sep 3;16(17):2971.