Analytical study of three cystatin C assays and their impact on cystatin C-based GFR-prediction equations.

in Clinica Chimica Acta (2008), 398(1-2), 118-24

BACKGROUND: Cystatin C-based equations are used to estimate GFR. However, three cystatin C immunoassays are on the market. Difference in cystatin C assays could have strong consequences on the accuracy ... [more ▼]

BACKGROUND: Cystatin C-based equations are used to estimate GFR. However, three cystatin C immunoassays are on the market. Difference in cystatin C assays could have strong consequences on the accuracy and precision of cystatin C-based equations. We have performed an analytical study of these three assays and studied potential differences between assays on the precision of cystatin C-based equations. METHODS: We have studied imprecision, recovery, linearity and interferences of the three immunoassays (nephelometric assay from Siemens and turbidimetric assays from Dako and Gentian). The impact of differences in cystatin C assays has been studied for the equations published by Levey (Siemens assay) and Grubb (Dako assay). RESULTS: Analytical performance of the Dako assay is slightly less high. For cystatin C values below 2.5 mg/L, no statistical difference is found between results given by the Dako and the Gentian assays. So, both assays can be used in the Grubb equation. Cystatin C results are different with the Siemens assay. The Levey equation, built with the Siemens assay, can only be used with cystatin C values measured with this assay. Using the Dako or Gentian assay results in the Levey equation can lead to differences in estimating GFR up to 6 mL/min/1.73 m2. Differences can reach 9.5 mL/min/1.73 m2 if the Siemens assay is used in the Grubb equation. CONCLUSION: The Siemens and Gentian assays seem analytically more valid than the Dako assay for cystatin C determination. Differences in cystatin C assays can lead to significant differences in cystatin C-based equations. However, these differences seem less important than the differences observed with creatinine and creatinine-based equations. [less ▲]

Cystatin C or Creatinine for Detection of Stage 3 Chronic Kidney Disease in Anorexia Nervosa.

in Nephron. Clinical Practice (2008), 110(3), 158-163

Background: Patients with anorexia nervosa (AN) are at a high risk of renal failure. Chronic kidney disease (CKD) is often missed in these patients because the serum creatinine is a poor marker of kidney ... [more ▼]

Background: Patients with anorexia nervosa (AN) are at a high risk of renal failure. Chronic kidney disease (CKD) is often missed in these patients because the serum creatinine is a poor marker of kidney function. We studied the utility of cystatin C to detect renal failure in this population. Method: Twenty-seven AN patients were studied. Glomerular filtration rates (GFR) were measured with the chromium-51- ethylenediaminetetraacetate ((51)Cr-EDTA) method. We compared the ability of creatinine and cystatin C to detect stage 3 CKD (GFR below 60 ml/min) by ROC curve analysis. Results: In this cohort, there is no correlation between GFR and serum creatinine, but there is a significant correlation between cystatin C and GFR. By ROC analysis, the cystatin C concentration is better than the serum creatinine concentration for the detection of stage 3 CKD (area under the curve of 0.86 vs. 0.61, p = 0.05). Conclusion: Plasma cystatin C is better than serum creatinine in detecting stage 3 CKD in patients with AN. [less ▲]

Creatinine calibration in NHANES: is a revised MDRD study formula needed?

in American Journal of Kidney Diseases (2008), 51(4), 709709-10

Cystatin C, renal function, and cardiovascular risk.

in Annals of Internal Medicine (2008), 148(4), 323

Prevalence of chronic kidney disease in Province of Liège: critical comparison with the American NHANES study?

Conference (2008)

Misdiagnosis of vitamin D insufficiency in subjects who received vitamin D2

in Clinical Chemistry (2008), 54(6), 110

Vitamine D2 ou vitamine D3?

in Revue de Médecine Interne (2008), 29(10), 815-20

PURPOSE: Nearly one billion people around the world are deficient in vitamin D and need to be supplemented. Vitamin D is available in medicines and fortified foods. It is available in two forms: vitamin ... [more ▼]

PURPOSE: Nearly one billion people around the world are deficient in vitamin D and need to be supplemented. Vitamin D is available in medicines and fortified foods. It is available in two forms: vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). KEY POINTS: The pharmacopeiae consider these steroid hormones as equivalent and interchangeable. However, several studies have showed that serum level of 25(OH)D is increased more effectively with vitamin D3 than vitamin D2. Vitamin D2 has shorter plasma half-life and a lower affinity for the vitamin D binding protein, the hepatic vitamin D hydroxylase and the vitamin D receptor. CONCLUSION: Vitamin D2 should not be regarded anymore as suitable for supplementation or fortification. Currently though, it is still the most used in some countries such as Portugal and Australia. [less ▲]

Actualite sur les effets de la vitamine D et l'evaluation du statut vitaminique D.

in Annales d'Endocrinologie (2008), 69(6), 501-10

Knowledge about vitamin D has greatly improved during the last few years. Vitamin D cannot any more be considered as exclusively necessary to prevent ricket/osteomalacia. Its role in the prevention of ... [more ▼]

Knowledge about vitamin D has greatly improved during the last few years. Vitamin D cannot any more be considered as exclusively necessary to prevent ricket/osteomalacia. Its role in the prevention of some osteoporotic fractures in the elderly (in association with calcium nutrition) is now well demonstrated and many epidemiologic and laboratory data argue for a role in the prevention of several diseases or anomalies (cancer, auto-immune diseases, cardiovascular events, sarcopenia...). A few intervention studies confirming some of these effects also exist. Vitamin D status can easily be assessed by measuring serum 25 hydroxy vitamin D (25OHD) level. However, many experts have claimed that the population-based reference values for 25OHD are too low and that the cut-off value below which vitamin D insufficiency can be present is somewhere between 20 and 40ng/mL with a clear tendency to target values above 30ng/mL (75nmol/L). The main consequences are that vitamin D insufficiency is highly frequent whereas the currently recommended supplementation doses are not sufficient. [less ▲]

Vitamin D treatment in chronic kidney disease: what we really need to know.

in Archives of Internal Medicine (2008), 168(18), 20452046

Chronic kidney disease in Taiwan.

in Lancet (2008), 372(9654), 19501950-1