Pregnancy in Lysinuric Protein Intolerance Complicated by Immune Dysregulation and Severe Thrombocytopenia.

Lysinuric protein intolerance (LPI) is a rare disorder of dibasic amino acid transport associated with secondary urea cycle defects and immune dysregulation. Pregnancy in LPI is seldom reported and presents significant management challenges. We report a 25-year-old woman with genetically confirmed LPI complicated by prior hemophagocytic lymphohistiocytosis (HLH) and systemic lupus erythematosus (SLE) who presented with an unplanned pregnancy. Early gestation was characterised by metabolic instability, including transient hyperammonaemia and elevated orotic acid, which improved with optimisation of nitrogen scavenger therapy and nutritional support. Progressive severe thrombocytopenia and anaemia developed during the second trimester and were managed as presumed immune thrombocytopenia with corticosteroids and intravenous immunoglobulin. Delivery by caesarean section at 35 weeks resulted in favourable maternal and neonatal outcomes. To our knowledge, this represents the first reported case of pregnancy in LPI complicated by established immune dysregulation (HLH and SLE) and severe thrombocytopenia, defining a previously uncharacterised high-risk phenotype with a favourable outcome.