Detecção precoce da nefropatia diabética

Abstract

Due to the unfavorable prognosis of advanced stages of diabetic nephropathy (DN), the ideal approach is to identify renal involvement as early as possible. It is recommended to measure urinary albumin excretion (UAE) annually, in random urine samples, in order to detect the stages of DN [microalbuminuria (UAE 17-174 mg/l or 30-300 mg albumin/g of creatinine) and macroalbuminuria (> 174 mg/l or > 300 mg/g)]. However, it has been suggested that UAE levels below the threshold of consensus could already signal the risk for DN progression and increased mortality, indicating the need to revise cutoff values. As a substantial amount of UAE (the immunounreactive fraction), is not detected by conventional methods, HPLC would be more sensitive to identify the presence of damage by measuring total UAE (immunoreactive + immunounreactive). Another recent observation is that diminished glomerular filtration rates (GFR) occurs in the presence of normoalbuminuria. Therefore, besides evaluating UAE, it is recommended to estimate GFR with equations employing creatinine; such as the Modification of Diet in Renal Disease (MDRD) study, available at www.mdrd.com. Owing to the known limitations of creatinine, alternative endogenous markers are being studied, and cystatin-C is a promising marker under investigation. Finally, new strategies that could detect DN even earlier, include biomarkers such as proteomics, defining a profile of urinary protein excretion able to identify the subsequent risk of renal disease.

Evaluation of urinary N-acetyl-beta-D-glucosaminidase as a marker of early renal damage in patients with type 2 diabetes mellitus

“…The exclusion criteria were body mass index (BMI) ≥ 30 kg/m 2 , history of other endocrinopathies, hypertension (median of blood pressure > 130/80 mmHg determined as triplicates, recorded in 2 different opportunities), urinary tract infection, renal lithiasis (discarded by kidney ultrasonography), proteinuria, abnormal urinary sediment (presence of hematuria, pyuria and/or casts) or renal failure [estimated glomerular filtration rate (eGFR) < 60 mL/min per 1.73 m 2 ] (12). Normoalbuminuria was defined as urinary albumin to creatinine ratio (ACR) < 30 mg/g and microalbuminuria as ACR = 30-300 mg/g (12,13). Diabetic patients were categorized into two groups based on their ACR: normoalbuminuria (n = 19) and microalbuminuria (n = 17).…”

“…Intra-assay variation coefficient was < 5%. Urinary concentration of albumin was assessed by an immunoturbidimetric method (Roche Diagnostics GmbH) and ACR was expressed as mg/g creatinine (12,13). Microalbuminuria was established when two out of three ACR determinations were found to be within the range 30-300 mg/g in a six-month period.…”

“…Creatinine concentration in urine and serum was measured by a kinetic method based on Jaffe reaction. Serum creatinine values were used to calculate an eGFR, by means of the abbreviated Modification of Diet in Renal Disease formula (8,13). Glycemic control was evaluated by assessing fasting plasma glucose and glycated hemoglobin (HbA 1c ).…”

Complicações cardiovasculares e renais no diabetes mellitus

“…A gravidade dessas lesões correlaciona-se com a taxa de filtração glomerular (TFG), grau de albuminúria, duração da diabetes, grau de controle da glicemia e fatores genéticos. Em virtude do prognóstico desfavorável das fases avançadas da nefropatia diabética, o ideal é identificar o envolvimento renal precocemente (MURUSSI et al, 2008).…”

“…Para o correto diagnóstico da nefropatia diabética, a American Diabetes Association recomenda que seja também estimada a TFG, independente de valores normais de excreção urinária de albumina (SESSO et al, 2008). A pesquisa deve ser confirmada em duas de três coletas, ao longo de seis meses, e deve ser feita no momento do diagnóstico para o tipo 2 e após cinco anos no tipo 1, ou eventualmente antes, se o controle glicêmico estiver muito inadequado, ou na adolescência (MURUSSI et al, 2008).…”