Assumpta Serra

Effect of drastic weight loss after bariatric surgery on renal parameters in extremely obese patients: long-term follow-up.

Obesity is a health problem that is reaching epidemic proportions. Extreme obesity (body mass index [BMI] > or =40 kg/m2) is a type of obesity that usually does not respond to medical treatment, with surgery being the current treatment of choice. Extreme obesity is associated with cardiovascular disease, type 2 diabetes, dyslipidemia, and hypertension. Recently, obesity has been related with high rate of renal lesions, but renal function and renal parameters in extreme obesity scarcely are documented. The objective of this study was to evaluate the effect of weight loss after bariatric surgery (BS) on BP, renal parameters, and renal function in 61 extremely obese (EO) patients after 24 mo of follow-up. A total of 61 EO adults (37 women) were studied prospectively before and 24 mo after surgery. Control subjects were 24 healthy, normal-weight adults (15 women). Anthropometric, BP, and renal parameters were determined. Presurgery weight, BMI, GFR, 24-h proteinuria, and 24-h albuminuria were higher in the EO patients than in control subjects (P < 0.001). All parameters improved at 12 mo after BS. However, during the second year of follow-up, only 24-h albuminuria (P = 0.006) and BMI (P = 0.014) continued to improve. At 24 mo after BS, obesity-related renal alterations considerably improved. This improvement was observed mainly in the first year after surgery, when the majority of weight loss occurred. However, 24-h albuminuria still improves during the second year of follow-up. It is possible that this decrease in 24-h albuminuria is not GFR related but rather is attributable to the persistence of the decrease in BMI and to the improvement of other weight-related metabolic factors.

Renal injury in the extremely obese patients with normal renal function

We studied the glomerular architecture in renal biopsies of 95 patients undergoing bariatric surgery for extreme obesity but whose renal function was normal. The comparison group was 40 control patients having protocol biopsies. These latter patients had normal weight and renal function, were non-diabetic, non-hypertensive, and were undergoing nephrectomy or donating a kidney. Logistic regression models determined associations between the clinical and biochemical variables and glomerular lesions. Arterial hypertension, sleep apnea syndrome (SAS), and microalbuminuria were prevalent in the obese patients, as was hyperglycemia to a lesser extent. Focal and segmental glomerulosclerosis was present in only five extremely obese (EO) patients but absent in controls. Increased mesangial matrix, podocyte hypertrophy, mesangial cell proliferation, and glomerulomegaly were more frequent in the obese cohort than in the control group. Body mass index was a significant independent risk factor associated with glomerular lesions in all 135 patients and in the 95 EO patients, whereas SAS was associated with glomerulomegaly only in the EO. Our study shows that EO patients who lack overt clinical renal symptoms have a variety of glomerular abnormalities that correlate with body mass.

Is there a need for changes in renal biopsy criteria in proteinuria in type 2 diabetes

Criteria for renal biopsy in proteinuric type 2 diabetes mellitus (T2DM) patients have been not defined. Usually criteria for renal biopsy in type 1 diabetes mellitus (T1DM) are used (microhaematuria, absence of diabetic retinopathy (DR), uncharacteristic change in renal function or immunological abnormalities). The aim of this study was to reconsider the indications for renal biopsy in T2DM using T1DM criteria, to determine whether they are useful in identifying patients with potentially treatable lesions. We studied 127 proteinuric patients with T2DM. Renal biopsy was performed in 35 who met the criteria for biopsy. Biopsy revealed diabetic glomerulopathy (DG) in 29 (83%) (in three associated with nondiabetic renal disease), immunoglobulin A (IgA) glomerulonephritis in three, focal glomerulosclerosis in one and normal glomeruli in two. DG was diagnosed in 17 (74%) of the patients without DR, in 18 (78%) of the patients with microhaematuria and in 10 (67%) of the patients with microhaematuria and without DR. All patients with DR had DG alone, except three with sudden unexpected changes in renal function. We conclude that DG is the most commonly found renal lesion in T2DM patients with proteinuria biopsied according to T1DM criteria, even in patients with microhaematuria or without retinopathy. Thus, these biopsy criteria are not useful in identifying patients with potentially treatable other renal diseases.

Adiponectin and risk of new-onset diabetes mellitus after kidney transplantation.

Background. New-onset diabetes mellitus after transplantation (NODAT) is a severe complication of kidney transplantation (KTx) with negative effects upon patient and graft survival. Several risk factors for NODAT have been described; however, the search for an early predictive marker is ongoing. It has recently been demonstrated that high concentrations of adiponectin (APN), which is an adipocyte-derived peptide with antiinflammatory and insulin-sensitizing properties, protect against future development of type 2 diabetes in healthy individuals. The purpose of this report was to study pretransplant insulin resistance and analyze pretransplant serum leptin and APN levels as independent risk factors for the development of NODAT. Methods. A total of 68 KTx patients were studied [mean age, 48±11 years; 70% males; body mass index (BMI), 25±3 kg/m2]; 31 KTx patients with NODAT and 37 KTx patients without NODAT (non-NODAT) with similar age, sex, BMI, immunosuppression, and posttransplant time were studied. All patients received prednisone and calcineurin inhibitors (75% tacrolimus and 25% cyclosporine A), and 76% of patients received mycophenolate mofetil. Family history of diabetes mellitus was recorded. Pretransplant homeostasis model assessment for insulin resistance (HOMA-IR) index was calculated from fasting plasma glucose and insulin. Pretransplant serum leptin and APN levels were determined by radioimmunoassay. Results. NODAT patients showed higher pretransplant plasma insulin concentrations [NODAT, 13.4 (11–22.7) &mgr;IU/mL; non-NODAT, 10.05 (7.45–18.4) &mgr;IU/mL; P=0.049], HOMA-IR index [NODAT, 4.18 (2.49–5.75); non-NODAT, 2.63 (1.52–4.68); P=0.043], and lower pretransplant serum APN concentration [NODAT, 8.78 (7.2–11.38) &mgr;g/mL; non-NODAT, 11.4 (8.56–15.27) &mgr;g/mL, P=0.012]. Inverse correlations between APN and BMI (r=−0.33; P=0.014) and APN and HOMA-IR index (r=−0.39; P=0.002) and between APN and NODAT (r=−0.31; P=0.011) were observed. Multiple logistic regression analysis showed the patients with lower pretransplant APN concentrations to be those at greater risk of developing NODAT [Odds Ratio=0.832 (0.71–0.96); P=0.01]. Conclusion. Pretransplant serum APN concentration is an independent predictive factor for NODAT development in kidney-transplanted patients.

Obesity, inflammation, and kidney disease

Obesity and extreme obesity are associated with a wide range of well known comorbidities (cardiovascular disease, dyslipidemia, hypertension, diabetes mellitus, metabolic syndrome). Recently, the association between obesity and renal involvement has been accepted since several epidemiological and pathological studies support this relationship. However, the physiopathological mechanism of this association is not completely understood. Different mechanisms have been implicated in the production of these renal lesions. Between them, metabolic alterations and inflammatory adipocytokines have been suggested. This paper is a review of the association between inflammatory adipocytokines or metabolic syndrome with renal involvement. We also briefly report our experience in a cohort of extremely obese patients.

Uromodulin and α1-Antitrypsin Urinary Peptide Analysis to Differentiate Glomerular Kidney Diseases

Background/Aims: Glomerular kidney disease (GKD) is suspected in patients based on proteinuria, but its diagnosis relies primarily on renal biopsy. We used urine peptide profiling as a noninvasive means to link GKD-associated changes to each glomerular entity. Methods: Urinary peptide profiles of 60 biopsy-proven glomerular patients and 14 controls were analyzed by combining magnetic bead peptide enrichment, MALDI-TOF MS analysis, and ClinProTools v2.0 to select differential peptides. Tentative identification of the differential peptides was carried out by HPLC-MS/MS. Results: The HPLC-MS/MS results suggest that uromodulin (UMOD; m/z: 1682, 1898 and 1913) and α1-antitrypsin (A1AT; m/z: 1945, 2392 and 2505) are differentially expressed urinary peptides that distinguish between GKD patients and healthy subjects. Low UMOD and high A1AT peptide abundance was observed in 80–92% of patients with GKD. Proliferative forms of GKD were distinguished from nonproliferative forms, based on a combination of UMOD and A1AT peptides. Nonproliferative forms correlated with higher A1AT peptide levels – focal segmental glomerulosclerosis was linked more closely to high levels of the m/z 1945 peptide than minimal change disease. Conclusion: We describe a workflow – urinary peptide profiling coupled with histological findings – that can be used to distinguish GKD accurately and noninvasively, particularly its nonproliferative forms.

Long-Term Normal Renal Function after Drastic Weight Reduction in Patients with Obesity-Related Glomerulopathy

Aims: No long-term studies of renal function evolution in morbidly obese (MO) patients after weight loss are available. The aim of our work was to ascertain the long-term influence of drastic weight reduction on renal function in MO patients with obesity-related glomerular lesions. Methods: 92 MO patients with normal renal function and biopsy evidence of mild obesity-related glomerulopathy underwent bariatric surgery (BS) and subsequent drastic weight loss. A long-term prospective follow-up (mean duration: 76 ± 42 months) was carried out. Basal renal biopsies and basal and long-term metabolic and renal function studies were performed in all cases. Linear mixed models were applied. Results: Blood pressure dropped early after BS and remained stable thereafter. Creatinine clearance and BMI fell in the first 2 years, rose slightly after 5 years and then remained stable. Serum creatinine and albuminuria decreased throughout the follow-up period. Renal function and albuminuria evolution showed non-significant differences in relation to the number of glomerular lesions. Conclusions: Drastic weight loss in BS-treated MO patients with pre-surgical normal renal function and mild obesity-related glomerular lesions is associated with short- and long-term maintenance of normal renal function and improvement in both arterial hypertension and albuminuria.

IGF1 modifications after bariatric surgery in morbidly obese patients: potential implications of nutritional status according to specific surgical technique.

OBJECTIVES IGF1 is decreased in morbidly obese (MO) patients and its changes after bariatric surgery weight loss (WL) are not well known. The aim of this study was to analyse IGF1 modifications in MO patients after WL and its relationship to ghrelin and to different types of surgeries. DESIGN Retrospective follow-up study at the University Medical Center. METHODS One hundred and nine MO patients (age 44.19.3, BMI 51.748.75KG/M(2)) were evaluated at baseline and 1 year after surgery: 28 sleeve gastrectomy (SG), 31 distal modified (m), and 50 ringed (r) Roux-en-Y gastric bypass (RYGBP) surgery. Changes in IGF1, IGFBP3, ratio IGF1:IGFBP3, and ghrelin were evaluated 1 year after surgery. RESULTS Baseline prevalence of low IGF1 (defined by s.d. IGF1<-2) was 22%, and %WL 1 year after surgery was 34.9±8.9%. There was a significant decrease in IGFBP3 in all the procedures, an increase in IGF1:IGFBP3 ratio in rRYGBP and SG, but total IGF1 only increased significantly in SG. Albumin concentrations decreased in mRYGBP, did not change in rRYGBP, but increased in SG after surgery. Total ghrelin concentrations increased after both RYGBPs and decreased after SG (P<0.05 in all cases). The prevalence of low IGF1 decreased in SG (28.6 vs 10.1%, P=0.03) and did not change in RYGPBP techniques. The %albumin change was the only dependent variable associated with the % total IGF1 change. CONCLUSIONS Recovery of low IGF1 after bariatric surgery was specifically related to the albumin modifications induced by surgery and was not related to ghrelin modifications.

Is adiponectin a marker of preclinical atherosclerosis in kidney transplantation

Cañas L, Bayés B, Granada ML, Ibernon M, Porrini E, Benítez R, Díaz JM, Lauzurica R, Moreso F, Torres A, Lampreabe I, Serra A, Romero R. Is adiponectin a marker of preclinical atherosclerosis in kidney transplantation? 
Clin Transplant 2011 DOI: 10.1111/j.1399‐0012.2011.01490.x. 
© 2011 John Wiley & Sons A/S.

Low Insulin-Like Growth Factor-1 Level in Obesity Nephropathy: A New Risk Factor?

Introduction IGF-1 (insulin-like growth factor-1) is a hormone involved in cell growth and other important processes. In the kidney, IGF-1 has a stimulating effect, increasing the blood flow and glomerular filtration rate. Although many experimental animal studies regarding the role of IGF-1 in the kidney have been conducted, few human studies are available in the literature. Obesity is a cause of renal failure, and several glomerular lesions associated with obesity have been described. However, no studies regarding the levels of IGF-1 in morbidly obese patients with renal injury associated with obesity have been conducted. Aim To determine the serum IGF-1 concentrations in morbidly obese patients with normal renal function but with different types of early obesity-related glomerular lesions and to evaluate the possible relationship between IGF-1 and the presence of renal lesions. Methods Eighty morbidly obese patients with renal biopsy, including 11 patients with no evidence of renal lesion, 17 patients with single glomerulomegaly, 21 patients with single podocyte hypertrophy, 10 patients with glomerulomegaly and podocyte hypertrophy, 5 patients with focal segmental hyalinosis, and 16 patients with increased mesangial matrix and/or mesangial proliferation, participated in this study. Biological parameters, including serum IGF-1 concentrations with the standard deviation score for age (SDS-IGF-1), were determined for all patients. Results Eighty patients (50 women and 30 men) with a mean BMI of 52.63 ± 8.71 and a mean age of 42.40 ± 9.45 years were included in this study. IGF-1, IGF-1 SDS and IGF-1BP3 levels according to the renal injury were compared (normal glomeruli: IGF-1 = 190.17 ± 72.46; glomerulomegaly: IGF-1 = 122.3 ± 50.05; podocyte hypertrophy: IGF-1 = 119.81 ± 60.34; focal segmental hyalinosis: IGF-1 170.98 ± 100.83, increased mesangial matrix and/or mesangial proliferation: IGF-1 117.73 ± 63.87). Statistically significant differences were observed between serum levels of IGF-1 and between the levels of SDS-IGF-1 by comparing the group without glomerular lesion with the group formed by patients with any type of glomerular injury. Logistic regression analysis was performed, with the dependent variable defined as the glomerular injury. In the multivariate analysis, only SDS-IGF-1 was associated with glomerular injury, and low levels of IGF-1 SDS were a risk factor for kidney injury. Conclusions Our study demonstrates that low IGF-1 serum levels are associated with renal lesions in morbidly obese patients without overt clinical renal manifestations.