The effect of ketogenic diet on thyroid functions in children with drug-resistant epilepsy.

BACKGROUND: Ketogenic diet (KD) remains a valuable treatment option for children with drug-resistant epilepsy. However, it may cause many well-known adverse effects such as dyslipidemia or kidney stones. But, its effects on thyroid functions are largely unknown. PURPOSE: The aim of this study was to investigate the effects of the KD on thyroid functions in children with drug-resistant epilepsy. METHOD: A total of 66 children (35 females) aged 3-193 months (median, 52 months) with drug-resistant epilepsy who received a KD for at least 12 months were enrolled in the study. All children were started on KD with 3:1 ratio which was then adjusted as clinically necessary. Serum free-thyroxine (FT4) and thyroid stimulating hormone (TSH) concentrations were measured before starting treatment and at the first, sixth and twelfth months of treatment. Changes in FT4 and TSH concentrations over 12 months were analyzed. RESULTS: Median serum FT4 and TSH concentrations, and the frequencies of patients with low FT4 and high TSH concentrations did not change significantly in the study sample over the 12-month study period. Serum FT4 levels increased significantly and TSH concentrations decreased insignificantly in four patients receiving L-thyroxine replacement therapy. During the 12-month treatment period, BMI-SDS increased, and the number of antiepileptic drugs decreased significantly. CONCLUSION: It appears that KD therapy does not impair thyroid functions in children with drug-resistant epilepsy. KD can be used safely along with L-thyroxine replacement even in children with pre-existing subclinical hypothyroidism.