Abstracts

Rationale: The ketogenic diet (KD) has been used since 1921 to treat children with medically refractory epilepsy. Early side effects of the KD include dehydration, acidosis, and hypoglycemia; growth failure, decreased bone mineral density, and nephrolithiasis may occur later. The International Ketogenic Diet Study Group recommends supplementation with a multivitamin containing B vitamins, vitamin D, iron, & calcium because of limited quantities of vitamin- & mineral-containing fruits, vegetables, & grains in the KD. Symptomatic deficiencies of B vitamins and vitamin D, & also selenium, rarely have been reported in children given the KD. We report a case of a girl who developed symptomatic scurvy (vitamin C deficiency) while receiving the KD for refractory epilepsy, despite multivitamin & mineral supplementation thought adequate. Methods: A nonverbal 12-year-old girl with refractory epilepsy and developmental delays had received a gastrostomy tube-fed, invariant blenderized, 2:1 KD for 8 y without major complications. Mild chronic acidosis was treated with enteric sodium bicarbonate. She presented with an illness of 2 mo duration, with: progressive feeding intolerance; microcytic anemia (without depression of platelets or leukocytes); recurrent bilateral knee swelling; and edema of both legs. Radiographs, magnetic resonance & nuclear medicine imaging suggested suprapatellar bursitis or osteomyelitis, with gelatinous conversion of the bone marrow and epiphysiolysis of both distal femurs and proximal tibias. The sedimentation rate and C-reactive protein were elevated. After 3 wk of antibiotic therapy she worsened, developing tachycardia, tachypnea, a requirement for weekly red blood cell transfusions, abdominal distension, bruising, & bleeding gums. The diagnosis of scurvy was suspected; it was found that due to recurrent episodes of feeding intolerance, her specialized KD vitamin mix had been inconsistently administered for several months. Results: A critically low serum vitamin C concentration (<5µmol/L; normal range 23-114) was found; concentrations of vitamins D, E, copper, & zinc were normal. All signs and symptoms rapidly improved after receiving 500 mg vitamin C daily for 14 d, followed by 250 mg daily; at 3 weeks of repletion, her serum vitamin C was 55µmol/L. Conclusions: Vitamin C is an essential nutrient necessary for collagen and neurotransmitter biosynthesis. However, in industrialized countries, most physicians have not seen scurvy, resulting in delayed diagnosis and prolonged evaluation. Few US or Western European children with scurvy have been reported, mostly in children with limited self-restricted diets due to autism spectrum disorder. All of our child’s signs and symptoms, including gelatinous conversion of the bone marrow, were explained by vitamin C deficiency; both her erratic intake, and her bicarbonate therapy (which decreases ascorbic acid absorption) likely played a role. More intensive monitoring of vitamin C intake, along with other micronutrients, is important in patients on chronic KD therapy. Funding: None