Abstracts

Rationale: Exact details of protocols for initiation of the ketogenic diet vary between different dietary therapies programs. Some programs empirically initiate sodium citrate or other alkalinizing agents. However, administration can be difficult due to poor taste, particularly in young orally-fed children. Parents are asked to give numerous supplements; simplification of their child’s regimen would be helpful. We aimed to determine risk factors for acidosis to determine if this should be standard practice.Methods: Retrospective chart review of patients initiated on the ketogenic diet at Children’s National Health System from 2009 through 2015.Results: Seventy patients were identified. Metabolic diagnoses included glucose transporter and pyruvate dehydrogenase deficiency, neurodegenerative brain iron accumulation, thiamine pyrophosphate deficiency, tyrosine hydroxylase dysfunction. Genetic diagnoses included Dravet and Rett syndromes, 19q duplication, KCNQ2 mutation, isodicentric chromosome 5, trisomy 21, trisomy 3, Aicardi, Pitt-Hopkins. Structural abnormalities were due to dysgenesis, prematurity or hypoxic-ischemic encephalopathy. Epilepsy syndromes included Doose, Lennox-Gastaut, super-refractory status epilepticus, refractory epilepsy/epileptic encephalopathy. Forty patients (57%) required an alkalinizing agent. Of these patients, 34 were initiated on 4:1 ketogenic diet; 5 were initiated on 3:1. One was already on citrate for chronic renal disease. 76% of the 25 patients on carbonic anhydrase inhibitors required citrate for acidosis. Of the 6 patients who did not, one was treated for refractory status epilepticus and did not achieve 3 to 4+ urine ketones until 6 days post initiation. Two were initiated at 3:1. Two were initiated under a gradual caloric advancement protocol. One was the patient on citrate for renal disease. Of those patients who did not require citrate and were not on a carbonic anhydrase inhibitor, 2 received lower ratios, 2:1 and 2.5:1. One was initiated under a gradual caloric advancement protocol. Two were managed by a decrease in ratio or by hydration. Of those patients who were on 4:1 and did not require citrate, many had a known underlying diagnosis (GLUT-1, Dravet, Lennox-Gastaut, trisomy 3, tuberous sclerosis, pyruvate dehydrogenase deficiency, Rett). One had been on modified Atkins diet previously.Conclusions: The ketogenic diet significantly benefits 38 to 50% of patients. Likely moreso than other treatments, its usage is impacted by tolerability. This review confirms that carbonic anhydrase inhibitors contribute to excessive acidosis, and supports the empiric initiation of citrate in those patients. Patients with epileptic encephalopathy of unclear cause may be prone to complications of dehydration and excessive acidosis, perhaps related to overall fragility or unidentified metabolic disorder; empirically starting citrate in these patients would be sensible. However, in patients with known underlying diagnosis and who are initiated at a lower ratio, expectant monitoring for acidosis with initiation of citrate only if needed, may optimize the likelihood that the diet will be well-tolerated.