Authors :
Presenting Author: Kori Porosnicu Rodriguez, MD, MPH – Johns Hopkins University School of Medicine
Mackenzie Cervenka, MD – Johns Hopkins University School of Medicine
Tanya McDonald, MD, PhD – Johns Hopkins University School of Medicine
Rationale:
Ketogenic diet therapy (KDT) is a valuable treatment option for patients with drug-resistant epilepsy. However, studies have suggested an increased risk of nephrolithiasis in patients on KDT. Most of these studies have been performed in pediatric populations with short-term follow up and there is a paucity of evidence from adult patients long-term. Our study addresses this gap by evaluating nephrolithiasis incidence in adults with epilepsy on KDT with long-term follow up of at least five years at a single center.
Methods:
Two-hundred eighty-five patients followed at the Johns Hopkins Adult Epilepsy Diet Center from June 2009 to September 2024 were screened for eligibility. Inclusion criteria included being 18 years or older and being on KDT (Classic Ketogenic Diet or modified Atkins diet) for at least five years. Chart review was conducted using the electronic medical record system and paper charts to capture demographic information, medication use, nephrolithiasis incidence, stone characteristics, associated complications, treatment, and recurrence. Student’s t-test, Fisher’s exact test, and Pearson’s chi-square were used in data analysis. Results:
Fifty-three adults met inclusion criteria with mean follow-up of 10.7 years (range: 6.3 to 14.9 years). Seven adults (13%) were on the classic ketogenic diet and 46 (87%) were on the modified Atkins diet. Fourteen (26%) developed nephrolithiasis following initiation of KDT. There was no statistically significant difference in age, gender, race, body-mass index at first visit, intellectual disability, as well as clinical characteristics including seizure types, diet type, family history of kidney stones, or pre-diet history of kidney stones between patients who developed nephrolithiasis and those who did not. The mean time to nephrolithiasis discovery was 5.6 years (range: 0.2 to15.3 years) after diet initiation. Of the 14 patients who developed nephrolithiasis, information regarding stone composition was only available for three patients (21%), with all three having calcium oxalate stones. Five (36%) had hydronephrosis and one (7%) had pyelonephritis at time of diagnosis, seven (50%) underwent lithotripsy, and 11 (79%) received recommendations to start or increase potassium citrate supplementation. All patients who developed nephrolithiasis continued KDT except for one patient who had already stopped the diet prior to renal calculus discovery. Two patients (14%) had nephrolithiasis recurrence.Conclusions: I
n our cohort, 14 patients (26%) developed kidney stones while on KDT, which is substantially higher than the ~8% incidence cited in previous literature. Despite 11 (79%) of these 14 patients starting or increasing potassium citrate dosing, two (14%) had recurrence of their kidney stones. Study findings support consideration of kidney stone prophylaxis such as potassium citrate supplementation as standard of care for all adults on KDT but also suggests that this measure alone may be insufficient. Funding:
Johns Hopkins Center for Refractory Status Epilepticus and Neuroinflammation