IFCC method for lactate dehydrogenase measurement in heparin plasma is unreliable.

that cardiac decompensation can be avoided in MCD-deficient patients. Finally, by analogy with fatty acid oxidation disorders such as medium-chain acyl-CoA dehydrogenase deficiency (13), one may conclude that knowledge of the diagnosis will improve outcome because early intervention is then possible in catabolic episodes that otherwise may lead to metabolic derange-ment. It therefore seems reasonable to suppose that early diagnosis and treatment can reduce the morbidity and mortality associated with MCD deficiency and to include MCD deficiency in neonatal metabolic screening programs. In this study, the malonylcarnitine concentration in the neonatal screening test card was increased in only one of the two patients investigated, but this was a problem of stability after sample storage for several years. We conclude that (a) malonylcarnitine is detectable by ESI-MS/MS, (b) malonylcarnitine is increased in the blood of patients with malonic aciduria, and (c) ESI-MS/MS-based neonatal screening programs should be able to detect patients with MCD deficiency, a treatable metabolic disorder, before the development of symptoms. A decarbox-ylase deficiency. Clinical and biochemical findings in a second child with a more severe enzyme defect. Association of malonyl-CoA decarboxylase deficiency and heterozygote state for haemoglobin C disease. A new case of malonyl coenzyme A decarboxylase deficiency presenting with cardiomyop-athy. Malonic aciduria presenting with developmental delay, malonyl carnitine increased in bloodspots [Abstract]. peroxisomal and cytoplasmic forms of malonyl-CoA decarboxylase and is mutated in malonyl-CoA decarboxylase deficiency. biochemical metabolite screen in the Munich ENU mouse mutagenesis project: determination of amino acids and acylcarnitines by tandem mass spectrometry. Various societies for clinical chemistry have proposed recommendations for the measurement of the activity of lactate dehydrogenase (LDH; l-lactate:NAD ϩ oxido-reductase; EC 1.1.1.27) (1–5). Depending on the pH of the buffer, the activity of LDH can be measured by the increase as well as the decrease in NADH. The optimum pH for the pyruvate-to-lactate conversion is 7.4 –7.8. The German (2) and French (5) Societies for Clinical Chemistry recommend this reaction. The IFCC (4) recommends the lactate-to-pyruvate conversion, for which the optimum pH is 8.8 –9.8. In our laboratory, we have measured LDH according to the recommendations of the French society (SFBC) for years. This measurement was routinely performed with a Modular analyzer (Roche GmbH). When this SFBC method for LDH measurement needed to be replaced because our supplier stopped producing the necessary reagents, we decided to introduce the method based on the recommendations of the IFCC. Because we did not …