Lipiduria in renal disease

Urinary Sediment Microscopy and Correlations with Kidney Biopsy: Red Flags Not To Be Missed

BACKGROUND

Urinary sediment is a noninvasive laboratory test that can be performed by an automated analyzer or manually by trained personnel. Manual examination remains the diagnostic standard because it excels at differentiating isomorphic from dysmorphic red blood cells and identifying other urinary particles such as renal tubular epithelial cells (RTECs), lipids, crystals, and the composition of casts. This study aimed to investigate the prevalence of a complete profile of urinary sediment particles and its associations with histologic lesions on kidney biopsy, regardless of diagnosis.

METHODS

This was a single-center, observational retrospective study of 131 patients who had contemporary manual urinary sediment evaluation and kidney biopsy. A comprehensive set of urinary particles and histologic lesions were quantified, and their associations were analyzed.

RESULTS

In our samples, we found an elevated frequency of findings suggestive of proliferative kidney disease and a low frequency of particles evoking urologic damage. The association of histologic lesions and urinary particles was explored with a multivariate model. We identified urinary sediment characteristics that independently correlated with the presence of some histologic lesions: urinary lipids with mesangial expansion (OR=2.86; 95% confidence interval [95% CI], 1.3 to 6.3), mesangial hypercellularity (OR=2.44; 95% CI, 1.06 to 5.58), and wire loops and/or hyaline deposits (OR=2.89; 95% CI, 1.13 to 7.73); Urinary renal tubular epithelial cells with endocapillary hypercellularity (OR=3.17; 95% CI, 1.36 to 7.39), neutrophils and/or karyorrhexis (OR=4.51; 95% CI, 1.61 to 12.61), fibrinoid necrosis (OR=4.35; 95% CI, 1.48 to 12.74), cellular/fibrocellular crescents (OR=5.27; 95% CI, 1.95 to 14.26), and acute tubular necrosis (OR=2.31; 95% CI, 1.08 to 4.97).

CONCLUSIONS

In a population of patients submitted to kidney biopsy, we found that the presence of some urinary particles (renal tubular epithelial cells, lipids, and dysmorphic erythrocytes), which are seldom reported by automated analyzers, is associated with active proliferative histologic lesions. In this regard, manual urinary sediment evaluation may help to shape the indications for performing a kidney biopsy.

The combined uro-radiological "Rendezvous" procedure, and an unusual CT and cystoscopic finding

The ureteric "rendezvous" procedure is an interventional procedure involving both uro-radiological and cystoscopic techniques to manage complex ureteric stenoses or fistulae. We present a case in which this procedure was utilised, with an unusual intra-procedural finding. Macroscopic visualisation of lipids within the urinary tract is an unusual finding at CT, and rarely seen at cystoscopy. The aetiology of lipiduria is varied; it may indicate the presence of unrecognised pathology, occur as a sequelae of trauma, or arise secondary to intervention. Understanding the patient's history is vital to determining the likely aetiology and significance of such a finding.

The role of the renin-angiotensin-aldosterone system in obesity-related renal diseases

Obesity is an independent risk factor for the development and progression of chronic kidney disease and one of the emerging reasons for end-stage renal disease owing to its dramatic increase worldwide. Among the potential underlying pathophysiologic mechanisms, activation of the renin-angiotensin-aldosterone-system (RAAS) plays a central role. Increased angiotensin II (AngII) levels also are central in hypertension, dyslipidemia, and insulin resistance, which, taken together with obesity, represent the metabolic syndrome. Increased AngII levels contribute to hyperfiltration, glomerulomegaly, and subsequent focal glomerulosclerosis by altering renal hemodynamics via afferent arteriolar dilation, together with efferent renal arteriolar vasoconstriction as well as by its endocrine and paracrine properties linking the intrarenal and the systemic RAAS, adipose tissue dysfunction, as well as insulin resistance and hypertension. The imbalance between increased AngII levels and the angiotensin converting enzyme 2/Ang (1-7)/Mas receptor axis additionally contributes to renal injury in obesity and its concomitant metabolic disturbances. As shown in several large trials and experimental studies, treatment of obesity by weight loss is associated with an improvement of kidney disease because it also is beneficial in dyslipidemia, hypertension, and diabetes. The most promising data have been seen by RAAS blockade, pointing to the central position of RAAS within obesity, kidney disease, and the metabolic syndrome.

A case of lipiduria after arterial embolization for renal angiomyolipomas

We report the case of a 31-year-old woman who suffered lipiduria after selective transcatheter arterial embolization for renal angiomyolipoma (AML). Computed tomography confirmed cystic liquefactive necrosis with fat-fluid level in AML. Although the process by which AML fat tissue excretion occurs is not clear, we speculated that the infarcted AML was connected to the urinary collection duct system and subsequently its adipose component was excreted into the urine.

Uroscopic rainbow: modern matula medicine

Visual inspection of a patient's urine has long been used by physicians, with colour recognised as having important clinical implications. In this review the authors will revisit this ancient pastime with relevance to contemporary medical practice.

Assessment of renal injury in vivo

The ICH S7A (Safety Pharmacology for Human Pharmaceuticals) guidelines specify that potential adverse pharmacologic effects of a test substance on renal function should be evaluated in supplemental studies when there is a cause for concern (ICH, 2001). For the most part, this can easily be accomplished by examination of the appropriate analytes in urine and blood collected as part of the routine preclinical safety studies. This review will serve as an overview of the selection, interpretation and limitations of standard clinical pathology methods (serum chemistry and urinalysis) for assessment of renal function in such studies, as well as provide some information on emerging biomarkers of renal function.

Predictive value of urinary micro-cholesterol (mCHO) levels in patients with progressive glomerular disease

BACKGROUND

Trace amounts of lipids are present in the urine of patients with glomerular disease, raising the possibility that the excess lipids reabsorbed by tubule cells may be toxic to these cells. In the present study, we assessed the prognostic value of micro-cholesterol (mCHO) levels in patients with chronic glomerular disease.

METHODS

The urinary mCHO levels of healthy subjects and patients with chronic kidney disease were measured by the enzymatic cholesterol cycling (ECC) method with a minimum detection level of 0.10 x 10(-3) mmol/L. First, the urinary mCHO levels of healthy subjects and 320 patients with various glomerular diseases with proteinuria >1000 mg/gCr were measured. Second, correlations of urinary mCHO levels with those of various other molecules, including albumin, IgG, IgM, transferrin, phospholipid, alpha1-microglobulin (alpha1MG), Apo A1, Apo A2, and Apo B, and urinary fatty body counts, were determined. Third, urinary mCHO, total protein (TP), albumin, and N-acetyl-beta-D-glucosaminidase (NAG) levels were measured longitudinally over 12 months (20.5 +/- 5.8 months) in 68 nondiabetic patients with impaired renal function [serum creatinine (Cr) > or = 1.5 mg/dL]. Correlations of the concentrations of urinary parameters in the initial 3-month period with the slopes of the reciprocal of creatinine versus time for the entire follow-up period were assessed by the ROC method and multiple regression analysis.

RESULTS

Urinary mCHO levels of the healthy subjects were 0.06 to 0.72 mg/gCr for males and 0.16 to 2.34 mg/gCr for females. Urinary mCHO levels in subjects with minimal change nephrotic syndrome were significantly lower than those in the patients with other glomerular diseases with massive proteinuria. Urinary mCHO levels correlated significantly with Apo A1 and Apo A2 levels, but not with urinary Apo B levels, in the latter subjects. The correlation coefficient of urinary fatty body counts (a marker of lipoprotein loading tubulopathy) with mCHO was higher than those with TP, albumin, IgG, IgM, and alpha1MG. The urinary mCHO elevation was significantly greater in patients who had a nonselective index of proteinuria than in those with a highly or moderately selective index. In nondiabetic patients with impaired renal function, the urinary mCHO level had a higher predictive value for rapid decline of renal function than TP, albumin, or NAG.

CONCLUSION

The urinary cholesterol level corresponds to the magnitude of urinary HDL excretion, and correlates with the degree of lipoprotein loading tubulopathy. Measurement of urinary mCHO by the ECC method is a simple and useful tool for predicting progression of chronic glomerular disease.

Interstitial nephritis

Interstitial nephritis is an inflammatory process within the renal interstitium, and was one of the first observations made in the description of renal histopathology. Many different conditions are associated with an interstitial nephritis, and as a clinical diagnosis the term has little use unless causation is defined. However, there has been recent interest in the possibility of a common mechanism causing irreversible renal damage and eventually renal failure in many different types of interstitial nephritis. Such damage could take place due to blood-borne inflammatory mediators, or could be due to renal tubular inflammation related to abnormal components of the glomerular filtrate in renal failure, such as proteins or lipids. If such research were to result in effective therapy for interstitial nephritis, the progression of many forms of renal disease to end stage renal failure could be ameliorated.