Serum folate concentrations in patients with cortical and subcortical dementias.

Folic acid is believed to play a role in protection from oxidant stress. Low levels of folic acid had been found in serum from patients with Alzheimer disease (AD). Folate concentration was evaluated in sera from 136 patients with cortical dementia [AD, n=108; frontotemporal dementia (FTD), n=28], 57 patients with subcortical dementia [Lewy body disease (LBD), n=9; corticobasal degeneration (CBD), n=5; progressive supranuclear palsy (PSP), n=6; Parkinson disease with dementia (PD-Dem), n=37], and 76 nondemented, healthy age-matched people. Serum folic acid levels were decreased in patients with AD and FTD as compared with either controls or patients with subcortical dementia (3.60+/-2.22 and 5.37+/-2.92 microg/L versus 6.87+/-3.50 microg/L, respectively; P<0.01). A tendency towards decreased folate concentration was found in LBD and CBD, but not to a significant extent. The highest proportion of folate-deficient patients was found in CBD, FTD and AD (respectively, 60, 48.2 and 46.3% versus 7.9% in controls; P<0.001). Folate deficiency characterizes FTD as well as AD. These differences observed among different clinical dementing syndromes may be related to neocortical damage.

Imprecision of tumour biomarker measurements on Roche Modular E170 platform fulfills desirable goals derived from biological variation.

BACKGROUND: Monitoring of test imprecision is one of the most important quality indicators in clinical laboratories. Imprecision goals should be derived from biological variation. The aim of this study was to evaluate the imprecision of eight tumour biomarker assays routinely measured on the Modular E170 system. METHODS: Method coefficient of variations (CVs) were obtained by an appropriate Internal Quality Control programme based on the measurement every working day of a fresh-frozen human serum pool with biomarkers concentrations around the clinical cut-offs. We evaluated data collected along the whole year 2008 (n range: 21-461); monthly CVs and their cumulative means were calculated and compared with corresponding goals. RESULTS: Biomarkers concentration means and average yearly CVs (desirable goals in parentheses) were as follows: alpha-fetoprotein, 9.6 microg/L, 3.9% (6.0%); CA125, 41.2 U/L, 2.8% (12.4%); CA15.3, 32.7 U/L, 3.1% (3.1%); CA19.9, 35.1 U/L, 2.8% (8.0%); CEA, 7.7 microg/L, 4.3% (6.4%); prostate-specific antigen (PSA), 4.1 microg/L, 4.3% (9.1%); CYFRA 21.1, 2.4 microg/L, 5.7% (11.3%); and ferritin, 64.5 microg/L, 4.0% (7.1%). CONCLUSIONS: Our study shows that in routine laboratory practice and over a clinically and analytically relevant time-span, the imprecision of the tumour biomarker measurements on the Roche Modular E170 fulfills desirable goals. For four assays (CA125, CA19.9, PSA and CYFRA 21.1) the optimum CV can even be achieved.

Intermethod variation in serum carcinoembryonic antigen (CEA) measurement. fresh serum pools and control materials compared.

This study was undertaken to evaluate the feasibility of using commercial control materials in a regional external quality assessment scheme (EQAS) for serum carcinoembryonic antigen (CEA) measurement. We have assessed the commutability of 12 commercial control materials using five automated immunochemical systems. We compared the intermethod behavior of the materials with that of 12-14 patient serum pools. In a total of 48 comparisons (12 materials x 4 pairs of analytical systems), seven instances of non-commutability were apparent, as shown by normalized residuals falling outside the +/-3 interval. The use of non-commutable materials generates two negative effects. In EQAS, the interlaboratory variation recorded is not representative of the variation expected in the assay of patient sera; in interlaboratory harmonization programs, recalibration with non-commutable materials increases, instead of decreasing, the interlaboratory variation. Both these effects were shown to occur in CEA measurement with the tested materials and systems. The materials planned to be used in our EQAS turned out to be commutable: this gave us the guarantee of measuring realistic interlaboratory variation values, although the check for commutability should be extended to all the analytical systems used by the participants in the scheme.