Objectives and Study: Total intestinal aganglionosis (TIA) is the rarest and the most severe form of Hirschsprung´s disease. Patients are dependent on long term parenteral nutrition (LTPN) and at risk of dehydration episodes, acute renal failure and hypercalcemia. The objective of this study was to identify the risk factors for hypercalcemia in children with TIA on LTPN.

Methods: We retrospectively analysed the medical records of 16 patients with TIA divided into 2 groups, group A who presented at least one episode of acute dehydration and hypercalcemia and group B (no history of hypercalcemia). Calcium & phosphorus status were analysed in blood and urine, PTH, 25-OHD3 plasma levels, kidney function, PN intake of calcium, phosphorus and bone mineral density (BMD) using X-ray absorptiometry. Values were reported as mean +/- SD or median [IQR].

Results: Both groups were composed of 8 children. No difference were found on steady state between the 2 groups in terms of blood calcium, phosphorus, urea, creatinine and glomerular filtration rate. Urinary calcium divided by creatininuria of group A was lower than group B (0,64 ± 0,60 vs 1,80 ± 1,28; p=0,03). Group A patients received higher PN calcium intake (0,49 ± 0,05 vs 0,40 ± 0,07 mmol/kg/day; p=0,02). On steady state PTH in group A was lower than in group B (20,8 ± 15,3 vs 32,5 ± 41,5 ng/l; p= 0,03) within the normal ranges (normal: 10-50 ng/l). In group A average PTH (ng/l) before and after hypercalcemia was within the normal range while reduced during the dehydration episode (pre-hypercalcemia 24.2 ± 7.4 vs per-hypercalcemia 8.2 ± 4.7 vs post-hypercalcemia 23.9 ± 6.7). Median BMD lumbar spine z-score was -0,2 [0,7] in both group.

Conclusion: Patients who presented at least one episode of acute dehydration associated with hypercalcemia received higher PN calcium intake, although they were in line with ESPGHAN guidelines. On steady state the hypercalcemia group had a lower urinary calcium excretion rate than group B. Patients with TIA presents high stool output and are at risk of acute and chronic dehydration. These data underline the importance to assess carefully the calcium metabolism during the follow-up of patients on LTPN for TIA with high stoma output. To prevent hypercalcemia it's important to correct rapidly acute dehydration episodes and on long term to provide high water-electrolytes supplementation, to limit calcium intake and to monitor plasma and urinary calcium, 25-OHD3 and PTH.