Endocrine Abstracts

Patients with central diabetes insipidus (CDI) and concurrent hypothalamic adipsia can experience significant sodium fluctuations requiring prolonged, recurrent hospital admissions and frequent serum sodium testing. We report a case of a 13-year-old male with adipsic CDI where the use of a point of care sodium analyser at home to titrate fluid and desmopressin administration resulted in stabilisation of his serum sodium, prevention of unplanned hospital admissions and improvement in his quality of life. Following a diagnosis of a low grade optic pathway glioma at 3 years of age, he was treated with multiple lines of chemotherapy (carboplatin/ vincristine/ cyclophosphamide/ cisplatin, thioguanine/ procarbazine/ CCNU/ vincristine (TPCV), bevacizumab/ irinotecan) as well as multiple neurosurgical procedures (two ventriculoperitoneal shunt insertions, four shunt revisions and two debulking surgeries). As a result of both the tumour and treatment he developed panhypopituitarism with adipsic CDI. Due to this, he had frequent fluctuations in serum sodium with multiple admissions for hyponatremia and hypernatremia. The year prior to starting the iSTAT machine he spent 155 days in hospital and sustained hypoxic brain injury due to severe dehydration secondary to hypernatraemia (peak serum sodium 170 mmol). To prevent future admissions, he required community blood testing three times a week to guide titration of fluids and desmopressin. We finally obtained funding for an iSTAT-1 machine at home, a point of care serum sodium analyser which gives results in 2 min with <100 μl of blood. In the year following the introduction of the iSTAT machine, the patient had no unplanned admissions, and stable sodium levels tightly controlled by fluid titration alone. This resulted in an estimated cost-saving of >£450 000 per annum. This case highlights how point of care sodium testing at home in patients with adipsic CDI can reduce hospital admissions, save healthcare costs and improve the long-term quality of life of brain tumour survivors.