Serum and tissue carnitine assay based on dialysis

Area of Science:

• Biochemistry
• Clinical Chemistry
• Metabolic Research

Background:

• Carnitine is essential for mitochondrial fatty acid metabolism and energy production.
• Accurate measurement of carnitine is crucial for diagnosing metabolic disorders.
• Existing assays may be affected by interfering substances in biological samples.

Purpose of the Study:

• To develop and validate a modified enzymatic assay for free carnitine in serum and tissues.
• To assess the assay's performance against a radioenzymatic method.
• To establish reference intervals and evaluate carnitine levels in specific patient populations.

Main Methods:

• A modified enzymatic assay utilizing dialysis to remove interfering substances.
• Conversion of carnitine to its acyl derivative using carnitine acetyltransferase and DTNB.
• Comparison with a radioenzymatic assay for validation.
• Application to serum, cerebrospinal fluid, and human tissue samples.

Main Results:

• The modified enzymatic assay demonstrated good agreement with the radioenzymatic method.
• Established a reference interval for serum carnitine as 28-70 mumol/L.
• Observed significantly lower serum carnitine levels in patients with advanced diabetes and those on valproic acid treatment.

Conclusions:

• The developed enzymatic assay is a reliable method for quantifying free carnitine in various biological matrices.
• Carnitine deficiency may be associated with advanced diabetes and valproic acid therapy.
• This assay facilitates clinical assessment of carnitine status.