Serum Creatinine: Not So Simple!

peer reviewedMeasuring serum creatinine is cheap and commonly done in daily practice. However, interpretation of serum creatinine results is not always easy. In this review, we will briefly remind the physiological limitations of serum creatinine due notably to its tubular secretion and the influence of muscular mass or protein intake on its concentration. We mainly focus on the analytical limitations of serum creatinine, insisting on important concept such as reference intervals, standardization (and IDMS traceability), analytical interferences, analytical coefficient of variation (CV), biological CV and critical difference. Because the relationship between serum creatinine and glomerular filtration rate is hyperbolic, all these CVs will impact not only the precision of serum creatinine but still more the precision of different creatinine-based equations, especially in low or normal-low creatinine levels (or high or normal-high glomerular filtration rate range)

Con: Should we abandon the use of the MDRD equation in favour of the CKD-EPI equation?

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Dual time-point FDG PET/CT for differentiating benign from malignant solitary pulmonary nodules in a TB endemic area

Objective. Fluorodeoxyglucose (FDG)-positron emission tomography (PET) is an accurate non-invasive imaging test for differentiating benign from malignant solitary pulmonary nodules (SPNs). We aimed to assess its diagnostic accuracy for differentiating benign from malignant SPNs in a tuberculosis (TB)-endemic area. Methods. Thirty patients, 22 men and 8 women, mean age 60 years, underwent dual time point FDG-PET/computed tomography (CT) imaging, followed by histological examination of the SPN. Maximum standard uptake values (SUVmax) with the greatest uptake in the lesion were calculated for two time points (SUV1 and SUV2), and the percentage change over time per lesion was calculated (%DSUV). Routine histological findings served as the gold standard. Results. Histological examination showed that 14 lesions were malignant and 16 benign, 12 of which were TB. SUVmax for benign and malignant lesions were 11.02 (standard deviation (SD) 6.6) v. 10.86 (SD 8.9); however, when tuberculomas were excluded from the analysis, a significant difference in mean SUV1max values between benign and malignant lesions was observed (p=0.0059). Using an SUVmax cut-off value of 2.5, a sensitivity of 85.7% and a specificity of 25% was obtained. Omitting the TB patients from analysis resulted in a sensitivity of 85.7% and a specificity of 100%. Mean %DSUV of benign lesions did not differ significantly from mean %DSUV of malignant lesions (17.1% (SD 16.3%) v. 19.4% (SD 23.7%)). Using a cut-off of %DSUV >10% as indicative of malignancy, a sensitivity of 85.7% and a specificity of 50% was obtained. Omitting the TB patients from the analysis yielded a sensitivity of 85.7% and a specificity of 75%. Conclusion. Our findings suggest that FDG-PET cannot distinguish malignancy from tuberculoma and therefore cannot reliably be used to reduce futile biopsy/thoracotomy

Chromato-panning: an efficient new mode of identifying suitable ligands from phage display libraries

<p>Abstract</p> <p>Background</p> <p>Phage Display technology is a well established technique for high throughput screening of affinity ligands. Here we describe a new compact chromato-panning procedure for selection of suitable binders from a phage peptide display library.</p> <p>Results</p> <p>Both phages and <it>E. coli </it>cells pass non-hindered through the interconnected pores of macroporous gel, so called <it>cryogel</it>. After coupling a ligand to a monolithic cryogel column, the phage library was applied on the column and non-bound phages were washed out. The selection of strong phage-binders was achieved already after the first panning cycle due to the efficient separation of phage-binders from phage-non-binders in chromatographic mode rather than in batch mode as in traditional biopanning procedures. <it>E. coli </it>cells were applied on the column for infection with the specifically bound phages.</p> <p>Conclusion</p> <p>Chromato-panning allows combining several steps of the panning procedure resulting in 4–8 fold decrease of total time needed for phage selection.</p

New and old GFR equations: a European perspective

peer reviewedABSTRACT Glomerular filtration rate (GFR) is estimated in clinical practice from equations based on the serum concentration of endogenous biomarkers and demographic data. The 2009 creatinine-based Chronic Kidney Disease Epidemiology Collaboration equation (CKD-EPI2009) was recommended worldwide until 2021, when it was recalibrated to remove the African-American race factor. The CKD-EPI2009 and CKD-EPIcr2021 equations overestimate GFR of adults aged 18–30 years, with a strong overestimation in estimated GFR (eGFR) at age 18 years. CKD-EPICr2021 does not perform better than CKD-EPI2009 in US population, overestimating GFR in non-Black subjects, and underestimating it in Black subjects with the same magnitude. CKD-EPICr2021 performed worse than the CKD-EPI2009 in White Europeans, and provides no or limited performance gains in Black European and Black African populations. The European Kidney Function Consortium (EKFC) equation, which incorporates median normal value of serum creatinine in healthy population, overcomes the limitations of the CKD-EPI equations: it provides a continuity of eGFR at the transition between pediatric and adult care, and performs reasonably well in diverse populations, assuming dedicated scaling of serum creatinine (Q) values is used. The new EKFC equation based on cystatin C (EKFCCC) shares the same mathematical construction, namely, it incorporates the median cystatin C value in the general population, which is independent of sex and ethnicity. EKFCCC is therefore a sex-free and race-free equation, which performs better than the CKD-EPI equation based on cystatin C. Despite advances in the field of GFR estimation, no equation is perfectly accurate, and GFR measurement by exogenous tracer clearance is still required in specific populations and/or specific clinical situations

Performances des nouvelles formules d’estimation du DFG dérivées de la créatininémie dans des populations européennes, africaines et brésiliennes

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G-8 indicates overall and quality-adjusted survival in older head and neck cancer patients treated with curative radiochemotherapy

Background: Evidence-based guidelines concerning the older head and neck cancer (HNCA) patient are lacking. Accurate patient selection for optimal care management is therefore challenging. We examined if geriatric assessment is indicative of long-term health-related quality of life (HRQOL) and overall survival in this unique population. Methods: All HNCA patients, aged >= 65 years, eligible for curative radio(chemo) therapy were evaluated with the Geriatric-8 (G-8) questionnaire and a comprehensive geriatric assessment (CGA). Euroqol-5 dimensions (EQ-5D) and survival were collected until 36 months post treatment start. Repeated measures ANOVA was applied to analyse HRQOL evolution in 'fit' and 'vulnerable' patients, defined by G-8. Kaplan-Meier curves and cox proportional hazard analysis were established for determination of the prognostic value of geriatric assessments. Quality-adjusted survival was calculated in both patient subgroups. Results: One hundred patients were recruited. Seventy-two percent of patients were considered vulnerable according to CGA (>= 2 abnormal tests). Fit patients maintained a relatively acceptable long-term HRQOL, whilst vulnerable patients showed significantly lower median health states. The difference remained apparent at 36 months. Vulnerability, as classified by G-8 or CGA, came forward as independent predictor for lower EQ-5D index scores. After consideration of confounders, a significantly lower survival was observed in patients defined vulnerable according to G-8, compared to fit patients. A similar trend was seen based on CGA. Calculation of quality-adjusted survival showed significantly less remaining life months in perfect health in vulnerable patients, compared to fit ones. Conclusions: G-8 is indicative of quality-adjusted survival, and should be considered at time of treatment decisions for the older HNCA patient

Performance de la nouvelle équation CKD-EPI (sans la variable ethnique) en transplantation rénale.

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