Can serum L-lactate, D-lactate, creatine kinase and I-FABP be used as diagnostic markers in critically ill patients suspected for bowel ischemia.

BACKGROUND: The prognostic value of biochemical tests in critically ill patients with multiple organ failure and suspected bowel ischemia is unknown. METHODS: In a prospective observational cohort study intensive care patients were included when the attending intensivist considered intestinal ischemia in the diagnostic workup at any time during intensive care stay. Patients were only included once. When enrolment was ended each patient was classified as 'proven intestinal ischemia', 'ischemia likely', 'ischemia unlikely' or 'no intestinal ischemia'. Proven intestinal ischemia was defined as the gross disturbance of blood flow in the bowel, regardless of extent and grade. Classification was based on reports from the operating surgeon, pathology department, endoscopy reports and CT-scan. Lactate dehydrogenase (LDH), creatine kinase (CK), alanine aminotransferase (ALAT), L-lactate were available for the attending physician. D-lactate and intestinal fatty acid binding protein (I-FABP) were analysed later in a batch. I-FABP was only measured in patients with proven ischemia or no ischemia. RESULTS: For 44 of the 120 included patients definite diagnostic studies were available. 23/44 patients (52%) had proven intestinal ischemia as confirmed by surgery, colonoscopy, autopsy and/or histopathological findings. LDH in these patients was 285 U/l (217-785) vs 287 U/l (189-836) in no-ischemia; p = 0.72. CK was 226 U/l in patients with proven ischemia (126-2145) vs 347 U/l (50-1427), p = 0.88. ALAT was 53 U/l (18-300) vs 34 U/l (14-34), p-0,56. D-lactate 0.41 mmol/l (0.11-0.75) vs 0.56 mmol/l (0.27-0.77), p = 0.46. L-lactate 3.5 mmol/l (2.2-8.4) vs 2.6 mmol/l (1.7-3.9), p = 0.09. I-FABP 2872 pg/ml (229-4340) vs 1020 pg/ml (239-5324), p = 0.98. Patient groups proven and likely ischemia together compared to unlikely and no-ischemia together showed significant higher L-lactate (p = 0.001) and higher D-lactate (p = 0.003). CONCLUSIONS: Measurement of LDH, CK, and ALAT did not discriminate critically ill patients with proven intestinal ischemia from those with definite diagnosis no-ischemia. However, L-lactate and D-lactate levels were higher in patients with proven or likely ischemia and need further study just as I-FABP.

Multicenter comparison study of current methods to measure 25-hydroxyvitamin D in serum.

OBJECTIVES: Measurement of serum 25-hydroxyvitamin D [25(OH)D] is generally considered to be a reliable indicator of vitamin D status. The recent increase in diversity of 25(OH)D assays prompted us to evaluate the performance of chromatographic methods (two in-house ID-LC-MS/MS and HPLC (ClinRep, Recipe)), a protein binding method (Cobas-25(OH)D-total, Roche) and immunochemical methods (Liaison and RIA (Diasorin), iSYS (IDS), ADVIA Centaur (Siemens), and Architect i1000 and i2000 (Abbott)). METHODS: Blood was drawn from randomly selected outpatients (N=60) at one site after informed consent. DEQAS and SRM 972 samples were obtained from the scheme organizer and NIST, respectively. Serum aliquots were prepared, frozen and transported to participating centers. Method comparison was performed according to CLSI-EP9 specifications. RESULTS: With these patient samples, and in comparison with ID-LC-MS/MS, Deming regression parameters slope, intercept and R were found to be within the ranges [0.57-1.07], [-1.7 to 6.9 nmol/L] and [0.88-0.98], respectively. 25(OH)D2 in DEQAS and SRM samples was fully recognized by chromatographic methods, but only partially by protein binding and immunochemical methods. Chromatographic methods, and to a lesser extent the protein binding assay, showed cross-reactivity with 3-epi-25(OH)D3. Agreement of 25(OH)D assays to ID-LC-MS/MS in sorting patients into distinct 25(OH)D categories varied between 53% and 88%. CONCLUSIONS: Significant bias exists between ID-LC-MS/MS and many, but not all, other 25(OH)D assays. The variable response among different assays for 25(OH)D metabolites impedes the use of uniform cut-off values for defining vitamin D status. Our results indicate the need towards further standardizing assays for 25(OH)D measurement.

Enzymology of the branched-chain amino acid oxidation disorders: the valine pathway.

Valine is one of the three branched-chain amino acids which undergoes oxidation within mitochondria. In this paper, we describe the current state of knowledge with respect to the enzymology of the valine oxidation pathway and the different disorders affecting oxidation.

Mutations in the gene encoding 3-hydroxyisobutyryl-CoA hydrolase results in progressive infantile neurodegeneration.

Only a single patient with 3-hydroxyisobutyryl-CoA hydrolase deficiency has been described in the literature, and the molecular basis of this inborn error of valine catabolism has remained unknown until now. Here, we present a second patient with 3-hydroxyisobutyryl-CoA hydrolase deficiency, who was identified through blood spot acylcarnitine analysis showing persistently increased levels of hydroxy-C(4)-carnitine. Both patients manifested hypotonia, poor feeding, motor delay, and subsequent neurological regression in infancy. Additional features in the newly identified patient included episodes of ketoacidosis and Leigh-like changes in the basal ganglia on a magnetic resonance imaging scan. In cultured skin fibroblasts from both patients, the 3-hydroxyisobutyryl-CoA hydrolase activity was deficient, and virtually no 3-hydroxyisobutyryl-CoA hydrolase protein could be detected by western blotting. Molecular analysis in both patients uncovered mutations in the HIBCH gene, including one missense mutation in a conserved part of the protein and two mutations affecting splicing. A carefully interpreted acylcarnitine profile will allow more patients with 3-hydroxyisobutyryl-CoA hydrolase deficiency to be diagnosed.

Hypertrophic cardiomyopathy, cataract, developmental delay, lactic acidosis: a novel subtype of 3-methylglutaconic aciduria.

3-Methylglutaconic aciduria is the biochemical marker of several inherited metabolic diseases. Four types of 3-methylglutaconic aciduria can be distinguished. In the type I form, accumulation of 3-methylglutaconate is due to deficient activity of 3-methylglutaconyl-CoA hydratase, an enzyme of the leucine degradation pathway. In the other forms, 3-methylglutaconic acid is not derived from leucine but is of unidentified origin, possibly derived from other metabolic pathways, such as mevalonate metabolism. We report five patients, all presenting a severe early-onset phenotype characterized by 3-methylglutaconic aciduria, hypertrophic cardiomyopathy, cataract, hypotonia/developmental delay, lactic acidosis, and normal 3-methylglutaconyl-CoA hydratase activity. This peculiar phenotype, for which a primary mitochondrial disorder is hypothesized, identifies a novel subtype of 3-methylglutaconic aciduria.

NMR spectroscopic studies on the late onset form of 3-methylglutaconic aciduria type I and other defects in leucine metabolism.

A diagnosis of 3-methylglutaconic aciduria type I (OMIM: 250950) based on elevated urinary excretion of 3-methylglutaconic acid (3MGA), 3-methylglutaric acid (3MG) and 3-hydroxyisovaleric acid (3HIVA) was made in a 61-year-old female patient presenting with leukoencephalopathy slowly progressing over more than 30 years. The diagnosis was confirmed at the enzymatic and molecular level. In vivo brain MR spectroscopic imaging (MRSI) was performed at 3.0 T, and one-dimensional and two-dimensional in vitro NMR spectroscopy of body fluids of the patient was performed at 11.7 T. Additionally, we measured 1D (1)H-NMR spectra of urine of seven patients with a total of four different inborn errors of leucine metabolism. Increased concentrations of 3HIVA, 3MGA (cis and trans) and 3MG were observed in the NMR spectra of the patient's urine. In the cerebrospinal fluid, the 3HIVA concentration was 10 times higher than in the plasma of the patient and only the cis isomer of 3MGA was observed. In vivo brain MRSI showed an abnormal resonance at 1.28 ppm that may be caused by 3HIVA. Comparison of (1)H-NMR spectra of urine samples from all eight patients studied, representing five different inborn errors of leucine metabolism, showed that each disease has typical NMR characteristics. Our leukoencephalopathy patient suffers from a late-onset form of 3-methylglutaconic aciduria type I. In the literature, only very few adult patients with this conditions have been described, and 3HIVA accumulation in white matter in the brain has not been presented before in these patients. Our data demonstrate that (1)H-NMR spectroscopy of urine can easily discriminate between the known inborn errors of leucine metabolism and provide the correct diagnosis.

Clinical, biochemical, and molecular findings in three patients with 3-hydroxyisobutyric aciduria.

3-Hydroxyisobutyric aciduria is a rare entity and affected individuals display a range of clinical manifestations including dysmorphic features and neurodevelopmental problems in the majority of patients. Here, we present two novel patients with 3-hydroxyisobutyric aciduria. To our knowledge, these are the 11th and 12th cases of 3-hydroxyisobutyic aciduria reported. It is believed that a deficiency in 3-hydroxyisobutyrate dehydrogenase is the most likely cause of this disorder. Measurement of 3-hydroxyisobutyrate dehydrogenase activity in fibroblasts homogenates of the two newly identified patients and a previously reported patient, however, revealed similar activities as in control fibroblasts. Since other enzymes with overlapping substrate specificity could conceal abnormal 3-hydroxyisobutyrate dehydrogenase activity, we cloned a candidate human cDNA for 3-hydroxyisobutyrate dehydrogenase (HIBADH). By heterologous expression in Escherichia coli, we showed that the product of the HIBADH gene indeed displays 3-hydroxyisobutyrate dehydrogenase activity. Mutation analysis of the corresponding gene in the patients suffering from 3-hydroxyisobutyric aciduria revealed no mutations. We conclude that HIBADH is not the causative gene in 3-hydroxyisobutyric aciduria.

3-Methylglutaconic aciduria type I is caused by mutations in AUH.

3-Methylglutaconic aciduria type I is an autosomal recessive disorder clinically characterized by various symptoms ranging from delayed speech development to severe neurological handicap. This disorder is caused by a deficiency of 3-methylglutaconyl-CoA hydratase, one of the key enzymes of leucine degradation. This results in elevated urinary levels of 3-methylglutaconic acid, 3-methylglutaric acid, and 3-hydroxyisovaleric acid. By heterologous expression in Escherichia coli, we show that 3-methylglutaconyl-CoA hydratase is encoded by the AUH gene, whose product had been reported elsewhere as an AU-specific RNA-binding protein. Mutation analysis of AUH in two patients revealed a nonsense mutation (R197X) and a splice-site mutation (IVS8-1G-->A), demonstrating that mutations in AUH cause 3-methylglutaconic aciduria type I.