Congenital nephrogenic diabetes insipidus presenting as osmotic demyelination syndrome in infancy: A case report.

RATIONALE: Almost 90% of congenital nephrogenic diabetes insipidus (NDI) cases are caused by mutations in the arginine vasopressin receptor 2 gene, which has X-linked recessive inheritance. Although NDI is commonly diagnosed in early infancy based on its characteristic findings, clinical diagnosis can be delayed when no other family members have been diagnosed with NDI because several findings of NDI are nonspecific. PATIENT CONCERNS: A 3-month-old boy diagnosed with NDI presenting with osmotic demyelination syndrome (ODS) was admitted for poor weight gain after birth and poor feeding during the week prior to admission. DIAGNOSIS: On admission, the initial blood examination showed hypernatremia (158 mmol/L), and treatment with intravenous fluids over the next 2 days further elevated the serum sodium level (171 mmol/L). After admission, polyuria was recognized, and polyuria in his grandmother and mother since childhood without a diagnosis of NDI was found. Magnetic resonance imaging showed multifocal, symmetrical lesions, including the lateral pons, on diffusion- and T2-weighted imaging, which led to a diagnosis of ODS. INTERVENTION: The infusion was stopped, and the patient was fed milk diluted 2-fold with water. OUTCOMES: The serum sodium level gradually decreased to 148 mmol/L over the course of 1 week. Low-sodium milk was started at 4 months of age and maintained a serum sodium level of approximately 140 mmol/L, which was within the normal range. The developmental quotient was 94 at 4 years of age. LESSONS: ODS is an encephalopathy resulting from extreme fluctuations in serum sodium concentration and plasma osmolality. ODS due to hypernatremia has been reported in several patients, although it usually occurs during rapid correction of hyponatremia. Consequences of the central nervous system are a critical complication of NDI that affects prognosis. These consequences can be avoided with treatment. Early blood examination or polyuria in the patient, mother, or another family member and hypernatremic dehydration with good urine output should lead to an early diagnosis and prevent central nervous system consequences.

A case of gray platelet syndrome masked by immune thrombocytopenia at presentation.

We report a case of gray platelet syndrome (GPS) associated with immune thrombocytopenia (ITP) at presentation. A 22-year-old male patient presenting with petechiae on his limbs was diagnosed with ITP due to a gradual decrease of his platelet count to a minimum of 26 × 10(9) /liter and an elevated platelet-associated IgG (PA-IgG) level in the absence of any other specific cause of thrombocytopenia. Administration of prednisolone increased his platelet count, but this dropped again to approximately 50 × 10(9) /liter as the dose was tapered, and remained at the same level after the treatment was terminated. Thirteen years later, we reassessed the cause of the thrombocytopenia because the PA-IgG level was found to be within the normal range. There were large hypogranular platelets on the blood film and a deficit of α-granules in the platelets on electron microscopy. On this basis, we diagnosed his thrombocytopenia as GPS. To our knowledge, this is the first report of a GPS case associated with ITP at presentation. This case illustrates the importance of carefully reviewing blood film results in the differential diagnosis of thrombocytopenia.