Kidney disease in patients with obesity: It is not always obesity-related glomerulopathy alone.

OBJECTIVE: Patients with obesity are at risk for chronic kidney disease. The aim is to characterize the spectrum of kidney disease in these patients, which may be related to obesity, termed obesity-related glomerulopathy (ORG), or may have other diseases secondary to associated or unassociated medical conditions. METHODS: Native kidney biopsies from 2000 to 2012 were retrospectively reviewed from all patients with body mass index >30kg/m2. Glomerular diameter was measured using a standard micrometer and clinicopathologic characteristics were analyzed. RESULTS: 4% (287) of all biopsies were obtained from patients with obesity (mean: weight 122kg, BMI 40.4±7.35kg/m2) for proteinuria in 93% and renal insufficiency in 53%. Frequent associated factors were abnormal glucose metabolism (31%), hypertension (60%), and obstructive sleep apnea (9%). Typical lesions of ORG were seen in 41% of cases and additional diseases in the rest. Glomerulomegaly, glomerular diameter >180µm, was present in 84% of cases (mean 224µm) vs normal size in 11% (mean 157µm), but was not increased with higher magnitude of obesity. Proteinuria was highest in patients with idiopathic FSGS (mean 8g/24h) and immune complex diseases (mean 7.4g/24h) and was mainly subnephrotic in obesity-related FSGS and tubulo-interstitial diseases. Creatinine levels were highest in tubulointerstitial diseases (mean 8.4mg/dL) and progressive diabetic nephropathy (mean 2.5mg/dL). CONCLUSIONS: Diverse kidney pathology superimposed on ORG is present in patients with obesity with varied clinical renal disease, some of which may be amenable for therapy. Kidney biopsy will assist in delineating these lesions for appropriate management and prognosis.

In-vitro myoglobin clearance by a novel sorbent system.

Rhabdomyolysis may lead to acute kidney injury following deposition of myoglobin in renal tubules. Although high-flux dialysis membranes may remove a substantial amount of myoglobin from plasma, this may still not be sufficient to prevent renal damage. We tested a new polymer sorbent, X-Sorb, in vitro to determine its potential to clear myoglobin from solutions. Normal saline or human serum in which myoglobin was dissolved was perfused by a peristaltic pump through a column packed with the sorbent. After a 4-hour perfusion, the myoglobin level in normal saline fell from 200,000 ng/ml to virtually undetectable (<780 ng/ml). Perfusion through the sorbent was then found to lower concentrations of dissolved myoglobin in 3 different 110-ml samples of human serum consistently by > 90% over 4 hours. X-Sorb appears to be an effective sorbent for myoglobin and warrants a trial in vivo to determine whether it is equally effective and safe.