Abstract
Background: In twin pregnancies complicated by twin-to-twin transfusion syndrome (TTTS) blood passes through unidirectional vascular shunts from the donor to the recipient twin. The donor twin consequently exhibits reduced growth velocity and oliguria. Proximal renal tubular dysgenesis (RTD) has been reported as a post mortem diagnosis in donor twins. We report a case of proximal RTD in a surviving donor twin.
Case Report: Monozygotic male twins were delivered at 30 weeks gestation for severe TTTS. The donor twin was initially hypotensive requiring inotropic support. He was oliguric for 12 days with a urine output of 0.1 ml/kg/hour. There was no acidaemia or significant hyperkalaemia. On day 20 his creatinine and urea peaked at 811 micromols/L and urea 39 mmols/L respectively. He developed hypertension and was managed with labetalol. By 30 days of life his urine output had normalised, although his creatinine remained elevated at 200 micromols/L. A renal biopsy performed at 12 weeks of age showed a paucity of proximal renal tubules consistent with proximal RTD.
Discussion: TTTS causes significant perinatal mortality and morbidity. In post mortem examination of donor twins with RTD a complete or near complete absence of proximal tubules and ischaemic glomeruli is has been described. It is postulated that RTD occurs as a consequence of chronic hypovolaemia resulting in hypoperfusion of the kidney and up-regulation of renin synthesis. Increased renin causes elevated levels of angiotensin II and subsequent vasoconstriction. Active apoptosis has also been described in RTD pathophysiology. Cardiovascular changes in survivors of TTTS are consistent with abnormalities of the renin-angiotensin system. The donor twin shows a protracted tendency towards vasoconstriction and hypertension that may lead to renal failure. Fetal renin gene expression may influence renal haemodynamics and amniotic fluid volumes in TTTS and thus may present an avenue for therapeutic interventions.
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Bhola, K., Hallam, L., Falk, M. et al. 197 Double Trouble: A Case of Proximal Tubular Dysgenesis in a Donor Survivor of Twin-To-Twin Transfusin Syndrome. Pediatr Res 58, 388 (2005). https://doi.org/10.1203/00006450-200508000-00226
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DOI: https://doi.org/10.1203/00006450-200508000-00226
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