Serum carnitine levels of children with epilepsy: Related factors including valproate

Blood Levels of Ammonia and Carnitine in Patients Treated with Valproic Acid: A Meta-analysis

Objective

Long-term valproic acid (VPA) administration is associated with adverse metabolic effects, including hyperammonemia and hypocarnitinemia. However, the pathogeneses of these adverse events remain unclear, and not enough reviews have been performed. The aim of this study was to conduct a meta-analysis of studies examining blood levels of ammonia and carnitine in patients treated with VPA.

Methods

We conducted database searches (PubMed, Web of Science) to identify studies examining blood levels of ammonia and carnitine in patients treated with VPA. A meta-analysis was performed to conduct pre- and post-VPA treatment comparisons, cross-sectional comparisons between groups with and without VPA use, and estimations of the standardized correlations between blood levels of ammonia, carnitine, and VPA.

Results

According to the cross-sectional comparisons, the blood ammonia level in the VPA group was significantly higher than that in the non-VPA group. Compared to that in the non-VPA group, the blood carnitine level in the VPA group was significantly lower. In the meta-analysis of correlation coefficients, the blood VPA level was moderately correlated with blood ammonia and blood free carnitine levels in the random effects model. Furthermore, the blood ammonia level was moderately correlated with the blood free carnitine level.

Conclusion

Although the correlation between ammonia and free carnitine levels in blood was significant, the moderate strength of the correlation does not allow clinicians to infer free carnitine levels from the results of ammonia levels. Clinicians should measure both blood ammonia and free carnitine levels, especially in patients receiving high dosages of VPA.

Effects of l-carnitine supplementation in patients with childhood-onset epilepsy prescribed valproate

BACKGROUND

The benefits of carnitine supplementation in patients treated with valproate (VPA) are not clear. Therefore, we retrospectively explored the benefits of carnitine supplementation by analyzing laboratory data.

METHODS

We measured the serum-free carnitine (FC), VPA, aspartate aminotransferase, alanine aminotransferase, amylase, and ammonia levels, and the platelet count, in 69 patients with childhood-onset epilepsy treated with VPA. Eight patients had received carnitine supplementation. The serum FC and acylcarnitine levels were measured using an enzyme cycling method. We compared laboratory values between patients with and without carnitine supplementation and analyzed the correlations between serum FC levels and laboratory values.

RESULTS

The serum FC levels were normal (median, 48.8 μmol/L; range: 41.9-68.3 μmol/L) in all eight patients with carnitine supplementation, but below normal in 32 of 61 patients without supplementation. The median serum amylase levels were lower in the patients with carnitine supplementation (median, 48 U/L; range: 27-149 U/L) than in those without (median, 7 U/L; range: 14-234 U/L). The platelet count and serum ammonia levels did not differ significantly between patients with and without supplementation. There was no significant correlation between the serum FC level and the platelet count, serum amylase level, or ammonia level.

CONCLUSIONS

Carnitine supplementation helps maintain serum FC levels in patients treated with VPA. The lower serum amylase levels in patients with carnitine supplementation may reflect protective effects of carnitine against latent pancreatic injury.

Factors associated with blood carnitine levels in adult epilepsy patients with chronic valproic acid therapy

AIMS

Valproic acid (VPA) is a widely used antiepileptic drug for the treatment of epilepsy, seizures, and bipolar and psychiatric disorders. A deficiency of carnitine, a compound involved in energy production, is associated with chronic VPA use. However, the clinical factors affecting blood carnitine levels and their pathophysiology remain unclear. Hence, we aimed to identify the factors that correlated with serum carnitine levels in epilepsy patients receiving chronic VPA therapy.

METHODS

This observational study included 138 epilepsy patients receiving chronic VPA therapy. Serum total and free carnitine levels, routine blood tests and drug concentrations were assessed. The correlation between carnitine levels and other factors were calculated using Spearman's rank correlation coefficients, and a principal component analysis (PCA) and a multiple linear regression analysis were performed.

RESULTS

Overall, serum free carnitine levels showed significant negative correlations with epilepsy duration, VPA treatment duration, daily VPA dose, and blood VPA concentration. A significant positive correlation was observed with erythrocyte count, hemoglobin levels, and creatinine levels. Of the 138 patients, 21 (15.2 %) with serum free carnitine levels of <20 μmol/L had significantly longer disease duration, a higher daily VPA dose, and lower blood clobazam concentrations. In the 48 VPA monotherapy patients, serum free carnitine levels showed a significant negative correlation with disease duration and duration of VPA therapy. Furthermore, in the 2.1 % patients receiving VPA monotherapy, serum free carnitine levels were <20 μmol/L. PCA resulted in seven factor solution (eigenvalue >1; 71.67 % explained variance). Component 1 clearly revealed the maximal loading for serum free carnitine level (.792) and the most negative loading for disease duration of epilepsy (-.595). A linear regression analysis revealed that the duration of epilepsy, serum creatinine level, and daily dose of VPA were significant (p < .01) factors that affected serum free carnitine levels.

CONCLUSIONS

The effects of combination therapy with VPA and other anti-epileptic drug(s) on carnitine levels are higher than that of VPA monotherapy. Additionally, epilepsy duration may affect serum free carnitine level.

Carnitine supplementation prevents carnitine deficiency caused by pivalate-conjugated antibiotics in patients with epilepsy prescribed valproate

We measured carnitine levels before and after pivalate-conjugated antibiotic (PCA) use in six patients with epilepsy who were prescribed valproate (VPA). Three of the patients were on carnitine supplementation when PCA use started. Serum FC levels were within the normal range (37.2-49.0 μmol/L) in all six patients before PCA use. After PCA use, the serum free carnitine (FC) levels remained within the normal range (48.0-68.2 μmol/L) in all three patients on carnitine supplementation, but were below the normal range (18.7-30.8 μmol/L) in the three patients not on carnitine supplementation. No remarkable changes in serum VPA levels, platelet count, amylase or ammonia level was evident in any patients in relation to PCA use. Carnitine deficiency due to PCA use was prevented by carnitine supplementation in patients with epilepsy who were taking VPA. Carnitine supplementation can support patients at risk of carnitine deficiency.

Management of antiepileptic drug-induced nutrition-related adverse effects

Although antiepileptic drugs (AEDs) are mainstay of the treatment of epilepsy, they are associated with significant adverse effects. The present study reviews the adverse effects of AEDs on some of the nutrition-related issues, including bone health, body weight, glucose and lipid metabolism, vitamin homeostasis, antioxidant defense system, and pregnancy. This paper also provides some nutritional recommendations for people with epilepsy. Patients with epilepsy should be regularly evaluated with regard to their nutrition status and any possible nutritional problems. Daily intake of adequate amounts of all nutrients from various sources should be encouraged, especially for vulnerable groups such as children, adolescents, elderly, and pregnant women. When necessary, preventative or therapeutic supplementation with appropriate micronutrients could be helpful. Graphical abstract.

Mass Spectrometric Analysis of L-carnitine and its Esters: Potential Biomarkers of Disturbances in Carnitine Homeostasis

PURPOSE

After a golden age of classic carnitine research three decades ago, the spread of mass spectrometry opened new perspectives and a much better understanding of the carnitine system is available nowadays. In the classic period, several human and animal studies were focused on various distinct physiological functions of this molecule and these revealed different aspects of carnitine homeostasis in normal and pathological conditions. Initially, the laboratory analyses were based on the classic or radioenzymatic assays, enabling only the determination of free and total carnitine levels and calculation of total carnitine esters' amount without any information on the composition of the acyl groups. The introduction of mass spectrometry allowed the measurement of free carnitine along with the specific and sensitive determination of different carnitine esters. Beyond basic research, mass spectrometry study of carnitine esters was introduced into the newborn screening program because of being capable to detect more than 30 metabolic disorders simultaneously. Furthermore, mass spectrometry measurements were performed to investigate different disease states affecting carnitine homeostasis, such as diabetes, chronic renal failure, celiac disease, cardiovascular diseases, autism spectrum disorder or inflammatory bowel diseases.

RESULTS

This article will review the recent advances in the field of carnitine research with respect to mass spectrometric analyses of acyl-carnitines in normal and various pathological states.

CONCLUSION

The growing number of publications using mass spectrometry as a tool to investigate normal physiological conditions or reveal potential biomarkers of primary and secondary carnitine deficiencies shows that this tool brought a new perspective to carnitine research.