Cystatin C or creatinine for detection of stage 3 chronic kidney disease in anorexia nervosa.

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.

New data on the intraindividual variation of cystatin C.

BACKGROUND: Cystatin C is a new interesting marker of glomerular filtration rate (GFR). However, data regarding its biological variance are scarce and conflicting. The ability of cystatin C to longitudinally follow renal function in patients therefore remains questionable. METHODS: 12 healthy subjects (6 men and 6 women) were included in the final statistical analysis. Serum creatinine, plasma cystatin C and GFR were measured twice after a 1-week interval on the same day, at the same time, and under the same preanalytical and analytical conditions. GFR was measured with an iohexol method. Serum creatinine was measured with a compensated Jaffé and an enzymatic method. Plasma cystatin C was measured by a particle-enhanced immunonephelometric method. Analytical (CV(A)) and within-subject (CV(I)) variances were classically calculated. RESULTS: CV(A) for creatinine (Jaffé and enzymatic methods) and cystatin C was 2.5, 0.97 and 1.29%, respectively. CV(I) was 5.8, 5 and 4.5% for the Jaffé creatinine, enzymatic creatinine and cystatin C determinations, respectively. CONCLUSION: Our study confirms that intraindividual variation of cystatin C and creatinine are similar. Therefore, from a biological point of view, cystatin C seems as accurate as creatinine for the longitudinal follow-up of renal function in daily clinical practice.

Pediatric gastric lymphoma: a rare entity.

Primary gastric lymphoma is a rare event in childhood. We describe a 13-year-old boy with gastric Burkitt-like lymphoma localized in the fundus. Symptoms mimicking gastritis-epigastric pain, hypochromic anemia, anorexia, and weight loss had been present for a few months before diagnosis. No Helicobacter pylori infection was shown at diagnosis. Biopsies obtained by ultrasound gastroscopy proved the diagnosis; F-fluorodeoxyglucose-positron emission tomography detected an isolated large gastric hypermetabolic mass. According to the international FAB/LMB 96 trial, the patient was treated with chemotherapy alone and is in first complete remission 2(1/2) years after diagnosis.

F-18 FDG PET in infectious diseases in children.

PURPOSE: The aim is to report our observations regarding the role of F-18 FDG PET in children's infectious processes. MATERIAL AND METHODS: A presentation is made of 3 neonatal infections unresponsive to treatment, 2 invasive infections in immunocompromised children, and 1 discitis in an immunocompetent child. PET or PET/CT was performed to address a specific question pertaining to the management of the diseases. Results were correlated with the clinical outcome. The impact on patient management is discussed. RESULTS: In 1 neonate, PET localized the infection in a bone which allowed surgical curettage. In another one, it localized the infection in recently renewed exogenous material and led to subsequent removal. It was negative in the third one, whose evolution was rapidly favorable. In the immunocompromised children, treatment of invasive infection was adapted according to the metabolic inflammatory activity of the disease. In a limping child with slight abnormalities on bone scintigraphy but major misleading involvement on MRI, PET/CT demonstrated hypermetabolism limited to a disc, thus avoiding further invasive procedures. CONCLUSIONS: Although not meant as a first choice examination, F-18 FDG PET should be considered in difficult cases of neonatal infection or in challenging diagnoses like discitis in the young child. It provides more accurate staging and treatment monitoring of the inflammatory process in invasive infections of immunocompromised children.

Is cystatin C useful for the detection and the estimation of low glomerular filtration rate in heart transplant patients?

Although previously studied in patients with chronic kidney disease, there is less data for the use of cystatin C and cystatin C-based formulas in heart transplant recipients. The ability of creatinine and cystatin C to detect renal failure (glomerular filtration rate [GFR] below 60 mL/min/1.73 m(2)) in heart transplant patients has been compared. The accuracy and precision of a creatinine-based formula (Modification of Diet in Renal Disease [MDRD]) versus a cystatin C-based formula (Rule's formula) to estimate GFR have also been studied. GFR was measured using the (51)Cr-ethylenediamine tetraacetic acid tracer in 27 patients. There was no significant difference between GFR and the reciprocal of creatinine or cystatin C. Receiver operating characteristic curves for cystatin C and creatinine were similar. Both formulas were well correlated with the GFR. The bias of the cystatin C-based was significantly better than one of the MDRD formula, but the standard deviation appeared better for the MDRD formula (bias of +3.9 mL/min/1.73 m(2) versus +12 mL/min/1.73 m(2) and SD of 8.5 versus 11.6, respectively). Plasma cystatin C has no clear advantage over serum creatinine to detect renal failure in heart transplanted patients.

Creatinine-based formulae for the estimation of glomerular filtration rate in heart transplant recipients.

Chronic renal failure (CRF) is a common complication in heart transplant patients. Serum creatinine has clear limitations for the detection and estimation of glomerular filtration rate (GFR). Various creatinine-based formulae are classically used for GFR estimation, but little scientific evidence exists for such use in a heart transplant population. GFR was measured using the plasmatic clearance of the glomerular tracer (51)Cr-EDTA in 27 heart transplant patients with two measures for 22 of the patients. Forty-nine measures were thus available for analysis. The precision and accuracy (Bland and Altman analysis) of the Cockcroft, simplified Modified Diet in Renal Diseases (MDRD) and new Mayo Clinic formulae were compared. The mean GFR of the population was 39 +/- 15 mL/min/1.73 m(2). All formulae were well correlated with the GFR. With the Bland and Altman analysis, the accuracy of the MDRD formula appeared higher than that of the Cockcroft or the Mayo Clinic formulae (bias of +12 mL/min/1.73 m(2), vs. +19.9 mL/min/1.73 m(2), and +22.1 mL/min/1.73 m(2), respectively). The difference between the estimated and measured GFR was higher than 20 mL/min/1.73 m(2) in 51% and 55% cases when using the Cockcroft and the Mayo Clinic formulae respectively, whereas the difference was only noted in 14% cases when the MDRD was used. Among creatinine-based formulae, the MDRD appears the most precise and accurate for estimating the GFR in heart transplant patients. However, when the GFR must be measured with high accuracy, we recommend the use of a reference method like inulin or (51)Cr-EDTA plasma clearance techniques.

18F-FDG PET in children with lymphomas.

PURPOSE: The aim of this study was to retrospectively evaluate the performance of positron emission tomography (PET) with 18F-fluorodeoxyglucose (18F-FDG) in children with lymphomas, at various stages of their disease. METHODS: Twenty-eight children (mean age 12.5 years, 14 girls, 14 boys) with Hodgkin's disease (HD, n=17) or non-Hodgkin's lymphoma (NHL, n=11) were evaluated. Patients were investigated at initial staging (n=19), early in the course of treatment (n=19), at the end of treatment (n=16) and during long-term follow-up (n=19). A total of 113 whole-body PET studies were performed on dedicated scanners. PET results were compared with the results of conventional methods (CMs) such as physical examination, laboratory studies, chest X-rays, computed tomography, magnetic resonance imaging, ultrasonography and bone scan when available. RESULTS: At initial evaluation (group 1), PET changed the disease stage and treatment in 10.5% of the cases. In early evaluation of the response to treatment (group 2), PET failed to predict two relapses and one incomplete response to treatment. In this group, however, PET did not show any false positive results. There were only 4/75 false positive results for PET among patients studied at the end of treatment (group 3, specificity 94%) or during the systematic follow-up (group 4, specificity 95%), as compared with 27/75 for CMs (specificity 54% and 66%, respectively). CONCLUSION: 18F-FDG-PET is a useful tool for evaluating children with lymphomas. Large prospective studies are needed to appreciate its real impact on patient management.