Recent studies have indicated that serum and plasma cystatin C are better markers for glomerular filtration rate (GFR) than serum creatinine, ubiquitously used for this purpose. To fully exploit the value of serum and plasma cystatin C as GFR markers, reliable age and sex-correlated reference intervals are required. The present study comprised cystatin C determinations in plasma and sera from 259 individuals from a well-defined area in the southernmost part of Sweden. From demographic lists two men and two women were randomly selected from each one-year birth cohort above 20 years of age. No sex differences were found for plasma and serum cystatin C, whereas an increase in the cystatin C levels with age was noted, corresponding to the known age-related decrease in GFR. The following reference intervals are recommended for practical clinical use: S-Cystatin C (both sexes): 20-50 years, 0.70-1.21 mg l-1 and 50+ years, 0.84-1.55 mg l-1. The same samples were also used for determination of beta 2-microglobulin levels in order to calculate reference intervals for the beta 2-microglobulin/cystatin C-ratio, which is a more distinct marker for cell proliferation, particularly lymphoproliferation, than is the serum level of beta 2-microglobulin alone, since the ratio should be virtually uninfluenced by GFR. The beta 2-microglobulin/cystatin C-ratios were uninfluenced by sex and age and 1.45-2.43 is recommended as the serum reference interval for practical clinical use. Serum creatinine was determined in the same samples and the creatinine level was found to be strongly influenced by sex and weakly by age.

One of the main determinants of plasma homocysteine in healthy subjects is serum creatinine. In the present study, we therefore investigated the relation between plasma homocysteine concentration, serum creatinine and a new marker for glomerular filtration rate, plasma cystatin C concentration. Cystatin C reflects the glomerular filtration better than serum creatinine and is not related to the muscle mass and formation of creatinine. The study group consisted of 255 healthy subjects from a well-defined area in the southern part of Sweden. The concentration of plasma homocysteine was increased in men compared to women. This difference disappeared when men and women were stratified by serum creatinine values. Statistically significant correlations were noted between plasma homocysteine and age, plasma cystatin C and serum creatinine. It is shown that plasma homocysteine is not only correlated to serum creatinine as a result of renal function but also as a result of the relationship between homocysteine production and creatine-creatinine synthesis. Using linear regression we were able to show that plasma cystatin C had a higher explanatory value than age. Serum creatinine showed a lower explanatory power than age. The findings in the present study might suggest that the increase of plasma homocysteine concentration with age could be partly due to the deterioration of renal function.

Alzheimer''s disease (AD) and frontotemporal dementia (FTD) are characterized by progressive neuronal loss and microvacuolization, although with different distributions of cortical involvement. In contrast to AD there is no amyloid, senile plaques or tangles in FTD. The involvement of chromosome 19 in AD has been associated with apoliprotein E (ApoE) and the Ε4 gene frequency has been related to increased risk and early onset of AD. Our analysis of frequency of the ApoE alleles in 38 patients with AD, 21 patients with FTD and 29 normal controls indicates an association of both AD and FTD with an increased frequency of the Ε4 allele and in AD also with homozygosity for Ε4. Our results might indicate that ApoE Ε4 is an important aggravating and pathoplastic factor in the presence of genetic and other determinants for the development of AD or FTD. A significantly higher Ε2 frequency in our FTD material compared to AD and normals might also indicate a connection with the distribution of cortical degeneration.

Alterations in plasma high density lipoproteins (HDL) were studied in thirty-eight male chronic alcoholics. Twenty-four (63%) of the patients had increased HDL protein (measured immunochemically) and twenty-five (66%) had increased HDL cholesterol (determined after polyanion precipitation of very low density lipoproteins (VLDL) and low density lipoproteins (LDL)). A statistically significant correlation was found between HDL protein and HDL cholesterol (r = 0.39). gamma-Glutamyltransferase (GT) was elevated in eighteen (47%) of the alcoholics. No significant correlations were found between GT and HDL protein or HDL cholesterol. The increase in HDL, as studied by rate zonal ultracentrifugation, was heterogeneous with changes in the HDL2 as well as HDL3 subfractions. It is suggested that determination of HDL total cholesterol, in combination with GT, may represent a valuable and sensitive test for detection of alcoholism.

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Background: Retinoids are vital for embryonic development; both excesses and deficiencies of vitamin A are known to give similar patterns of birth defects. Concentrations of retinol in newborns and in pregnant women have been investigated, but concentrations of the biologically active metabolite all-trans retinoic acid and its isomer 13-cis retinoic acid have not. Objective: We measured serum concentrations of these retinoid derivatives in newborns and their mothers and in women in the first trimester of pregnancy, when embryonic differentiation (organogenesis) takes place. Design: In this descriptive study, 10 newborns from normal deliveries and their mothers and 16 healthy women in their first trimester of pregnancy were studied. Seventeen healthy women served as control subjects. all-trans and 13-cis Retinoic acid and retinol concentrations were measured by HPLC. Results: The newborns had significantly lower retinol concentrations (1.0 mol/L) than did their mothers (1.7 mol/L; P ҃ 0.013). Serum all-trans retinoic acid was also significantly lower in the newborns (3.4 nmol/L) than in their mothers (5.8 nmol/L; P ҃ 0.008). In addition, serum concentrations of 13-cis retinoic acid were significantly lower in the newborns (2.0 nmol/L) than in their mothers (2.6 nmol/L; P ҃ 0.005). The serum concentrations of all-trans retinoic acid and retinol did not correlate in any group. Conclusion: Retinol concentrations do not accurately reflect the concentrations of the biologically active derivative all-trans retinoic acid.Am J Clin Nutr 2005;81:633-6.

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