Comparison of two iron gluconate treatment modalities in chronic hemodialysis patients: results of a randomized trial.

BACKGROUND: Iron supplementation in chronic hemodialyzed patients is not yet completely defined concerning the dosing regimen. This study aimed to evaluate the effects of the same iron load administered in different regimens on anemia, iron status and the reticulocyte (Ret) subpopulation patterns in stable patients on chronic hemodialysis (HD). PATIENTS AND METHODS: Seventeen patients undergoing thrice-weekly chronic HD and receiving stable alphaerythropoietin therapy with absolute iron deficiency (transferrin saturation (TSAT) <20%, ferritin (Frt) <100 ng/mL) were randomly divided into two groups: group A (n=9) received 20.8 mg of sodium iron gluconate at the end of each dialysis session; group B (n=8) 62.5 mg only at the end of the 1st dialysis session of the week. The treatment period lasted 3 months (period 1) and was followed by 3 months of observation (period 2). RESULTS: Both treatments increased hemoglobin (Hb) levels by an average of 0.90 g/dL in period 1, with a progressive decline in period 2 (p=ns between groups), peaking at 11.2 g/dL in group A and 10.8 g/dL in group B. The effects on mean red blood cell volume and Hb concentrations were similar. Frt levels more than doubled during period 1 and early in period 2 in both groups (172 microg/L in group A; 149 microg/L in group B, and progressively decreased in period 2 (p=ns between groups). The TSAT index increased progressively peaking to 28.7% in group A and 24.3% in group B. Hypochromic red blood cells (hypocRBC) decreased early from 5.6-2.2% in group A, and from 5.5-2.1% in group B, and persisted in period 2; the between-period differences for the combined groups were statistically significant (p=0.0051). High fluorescence reticulocytes (HFR) increased from period 1 to period 2 only in group B (from 0.8-1.7%, p=0.012). CONCLUSIONS: Both regimens replenished iron stores and improved anemia. The HFR increase in group B could be due to soluble transferring receptor (STnfR) gene upregulation; alternatively it could indicate the prevalence of immature Ret release from bone marrow.

Guidelines for the analysis of Bence Jones protein.

The detection and quantification of monoclonal free light chains in urine (Bence Jones protein, BJP) are thorny issues for the laboratorian. Immunoelectrophoretic techniques (immunofixation) allow the characterization of the two pathognomonic features of light chains: monoclonality and absence of heavy chains. Immunochemical methods such as nephelometry and turbidimetry are widely used in clinical practice to exclude the presence of BJP. However, these methods are limited by several metabolic and analytical problems. The accuracy of quantitative immunochemical methods is hampered by the heterogeneous molecular forms (fragments and polymers) of BJP and by the lack of reference materials, and the precision of the methods in clinically relevant regions of the dynamic range is poorly defined. Immunoelectrophoretic methods, especially immunofixation, are recommended because of their ability to demonstrate monoclonality and the absence of heavy chains. Immunofixation is also considered the best method to document the disappearance of the monoclonal protein (complete remission). The physiology of immunoglobulins and the clinical relevance of BJP are illustrated in the two appendices to this paper.

Fractional excretion of IgG predicts renal outcome and response to therapy in primary focal segmental glomerulosclerosis: a pilot study.

BACKGROUND: Prolonged treatment with steroids and/or cyclophosphamide improves the prognosis of primary focal segmental glomerulosclerosis (FSGS). In nephrotic patients, no clinical or histological feature predicts responsiveness to therapy. METHODS: In 50 patients with FSGS, fractional excretion (FE) of immunoglobulin G (IgG), albumin, transferrin, and alpha(1)-microglobulin (alpha(1)m) was calculated. The aim of the study is to assess whether FE IgG and FE alpha(1)m: (1) correlate with histological lesions, (2) predict outcome, and (3) may be useful to guide therapy. RESULTS: The association of FE IgG with percentage of glomeruli with segmental sclerosis was at the limit of significance (P = 0.01). FE alpha(1)m was associated with extent of tubulointerstitial damage (P = 0.008). By multiple regression analysis, FE alpha(1)m was dependent on FE IgG (R(2) = 0.76; P = 0.000). The predictive value of proteinuric variables on outcome was evaluated in 29 patients with nephrotic syndrome and baseline normal renal function (serum creatinine level, 1.04 +/- 0.22 mg/dL [92 +/- 19 micromol/L]; follow-up, 50 +/- 33 months); remission rates were 91% and 0% in patients with FE IgG less than versus greater than 0.140 (P = 0.0009). By multiple logistic regression analysis, only FE IgG was associated with remission (P = 0.043). Proteinuria less than versus greater than 7.5 g/d of protein predicted end-stage renal failure (0% versus 36%; P = 0.004); the predictive value of FE IgG less than versus greater than 0.140 was higher (0% versus 71%; P = 0.0000). Patients with FE IgG less than 0.025 were responsive to steroids alone (70%) or steroids and cyclophosphamide (20%); patients with FE IgG greater than 0.025 and less than 0.140 were responsive to steroids alone (20%) or steroids and cyclophosphamide (80%); and 100% of patients with FE IgG greater than 0.140 were unresponsive to therapy (P = 0.000). CONCLUSION: In FSGS, FE IgG is at the limit of statistically significant association with segmental sclerosis, and FE alpha(1)m is associated with extent of tubulointerstitial damage. FE IgG shows the best predictive value for remission, progression, and response to therapy and may be useful to guide treatment. Am J Kidney Dis 41:328-335.

Urinary N-acetyl-beta-glucosaminidase excretion is a marker of tubular cell dysfunction and a predictor of outcome in primary glomerulonephritis.

BACKGROUND: The urinary excretion of N-acetyl-beta-glucosamynidase (NAG) is increased in subjects exposed to substances toxic for renal tubular cells. In experimental and human glomerular diseases, its increased excretion is probably due to the dysfunction of tubular epithelial cells induced by increased traffic of proteins in the tubular lumen. The first aim of this study was to evaluate whether NAG excretion is correlated not only with the amount of proteinuria but also with some proteinuric components which reflect both glomerular capillary wall damage (IgG) and an impairment of tubular reabsorption of microproteins (alpha(1) microglobulin). The second aim was to assess whether NAG excretion has a predictive value on functional outcome and response to therapy. METHODS: In 136 patients with primary glomerulonephritis [74 with idiopathic membranous nephropathy (IMN), 44 with primary focal segmental glomerulosclerosis (FSGS) and 18 with minimal change disease (MCD)] urinary NAG excretion was measured by a colorimetric method and expressed in units per gram of urinary creatinine. RESULTS: Using univariate linear regression analysis NAG excretion in all 136 patients was significantly dependent on IgG excretion, 24-h proteinuria, fractional excretion of alpha(1) microglobulin (FE alpha(1)m) and diagnosis. Using multiple linear regression analysis, NAG excretion was significantly dependent only on IgG excretion and 24-h proteinuria. Limiting the analysis to 67 patients with nephrotic syndrome (NS) and baseline normal renal function, by multiple linear regression, NAG excretion was significantly dependent on IgG excretion (P=0.0004), 24-h proteinuria (P=0.0067) and FE alpha(1)-m (P=0.0032) (R(2)=0.63). In 66 patients with NS and normal baseline renal function (MCD 10 patients; FSGS 20 patients; IMN 36 patients), according to values below or above defined cut-offs (IMN, 18 U/g urinary Cr; FSGS and MCD, 24 U/g urinary Cr), NAG excretion predicted remission in 86 vs 27% of IMN patients (P=0.0002) and 77 vs 14% of FSGS patients (P=0.005). Progression to chronic renal failure (CRF) was 0 vs 47% in IMN patients (P=0.001) and 8 vs 57% in FSGS patients (P=0.03). Using Cox model, in IMN patients only NAG excretion (P=0.01, RR 5.8), but not 24-h proteinuria, predicted progression to CRF. All MCD patients had NAG excretion values below the chosen cut-off, and 90% of them developed remission. Response to immunosuppressive therapy was significantly different in patients with NAG excretion values below or above the cut-offs. CONCLUSION: Urinary NAG excretion can be considered as a reliable marker of the tubulo-toxicity of proteinuria in the early stage of IMN, FSGS and MCD; the excretion values show a significant relationship with 24-h proteinuria, IgG excretion and FE alpha(1)m. Its determination may be a non-invasive, useful test for the early identification of patients who will subsequently develop CRF or clinical remission and responsiveness to therapy.