Urine Albumin-to-Creatinine Ratio
UrináliseÚltima revisão: 7 de abril de 2026. Abordagem de fontes: contexto padrão de interpretação laboratorial, material médico de referência e orientações clínicas ou de saúde pública quando relevantes.
O que é Urine Albumin-to-Creatinine Ratio?
The urine albumin-to-creatinine ratio (UACR) is a convenient and standardized method for quantifying urinary albumin excretion from a spot (random) urine sample, eliminating the need for a timed 24-hour urine collection. Albumin is a large protein that is normally retained by the glomerular filtration barrier. When the kidneys are damaged, this barrier becomes more permeable, allowing albumin to leak into the urine—a condition known as albuminuria. By dividing the urine albumin concentration by the urine creatinine concentration, the UACR corrects for variations in urine dilution, providing a reliable estimate of daily albumin excretion.
UACR is the recommended test for detecting and monitoring albuminuria, which is a hallmark of diabetic kidney disease and a key marker in the staging of chronic kidney disease (CKD). Current KDIGO guidelines classify albuminuria into three categories: normal to mildly increased (<30 mg/g), moderately increased (30–300 mg/g, formerly called "microalbuminuria"), and severely increased (>300 mg/g, formerly called "macroalbuminuria"). UACR is also an independent cardiovascular risk factor—elevated albuminuria predicts heart attack, stroke, and heart failure even in the absence of overt kidney disease.
Por que isso importa
UACR is one of the earliest detectable markers of kidney damage, often appearing years before eGFR begins to decline. In diabetes, persistent moderately increased albuminuria is the first clinical sign of diabetic nephropathy and identifies patients who benefit most from intensified treatment with RAAS inhibitors (ACE inhibitors or ARBs), SGLT2 inhibitors, and tight glycemic control. UACR is also a powerful cardiovascular risk predictor—each doubling of UACR is associated with a 29% increase in cardiovascular mortality. Monitoring UACR allows clinicians to detect kidney damage early, guide treatment decisions, and track response to therapy.
Faixas de referência normais
| Grupo | Faixa | Unidade |
|---|---|---|
| Normal | <30 | mg/g |
| Moderately increased (microalbuminuria) | 30–300 | mg/g |
| Severely increased (macroalbuminuria) | >300 | mg/g |
As faixas de referência podem variar entre laboratórios. Sempre compare seus resultados com as faixas fornecidas pelo seu local de exame.
O que significam níveis altos de UACR
Causas comuns
- Diabetic nephropathy (most common cause globally)
- Hypertensive nephrosclerosis
- Glomerulonephritis (IgA nephropathy, membranous, focal segmental glomerulosclerosis)
- Lupus nephritis
- Preeclampsia
- Heart failure
- Urinary tract infection (transient elevation)
- Intense exercise or fever (transient elevation)
- Obesity
Possíveis sintomas
- Usually asymptomatic in early stages
- Foamy or frothy urine (with significant proteinuria)
- Swelling in feet, ankles, or around eyes (nephrotic range)
- Fatigue
- Elevated blood pressure
O que fazer: Elevated UACR should be confirmed with at least two of three specimens over 3–6 months, as transient causes (exercise, UTI, fever) can produce false positives. If persistently elevated, evaluate for underlying causes: check blood glucose and HbA1c (diabetes), blood pressure, serum creatinine and eGFR, serum albumin, and urinalysis for active sediment. Treatment focuses on the underlying cause and renoprotective measures: ACE inhibitors or ARBs reduce albuminuria and slow CKD progression, SGLT2 inhibitors provide additional renoprotection, and blood pressure and glycemic targets should be optimized.
O que significam níveis baixos de UACR
Causas comuns
- Normal kidney function
- Effective treatment reducing albuminuria
Possíveis sintomas
- No symptoms associated with low UACR
O que fazer: A UACR below 30 mg/g is normal and indicates intact glomerular filtration barrier function. Continue regular screening if risk factors are present (diabetes, hypertension). A reduction in UACR with treatment correlates with improved renal and cardiovascular outcomes.
Quando o exame de UACR é recomendado?
- Annual screening in all patients with diabetes (type 1 after 5 years, type 2 at diagnosis)
- Annual screening in patients with hypertension
- Evaluation and staging of chronic kidney disease
- Monitoring response to renoprotective therapy (ACE inhibitor, ARB, SGLT2 inhibitor)
- Cardiovascular risk assessment
- Preeclampsia evaluation in pregnancy
Perguntas frequentes
Biomarcadores relacionados
Referências e abordagem de revisão
As páginas do glossário de biomarcadores são explicações educativas e devem ser interpretadas junto com as faixas de referência e observações fornecidas pelo seu laboratório e pelo seu médico. Para conhecer nossos padrões editoriais e processo de revisão, veja nossa Política editorial e a nossa revisão de conteúdo.
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Enviar resultados de exames →Aviso médico: Estas informações são apenas educativas e não substituem orientação, diagnóstico ou tratamento médico profissional. As faixas de referência podem variar entre laboratórios. Sempre converse com seu profissional de saúde sobre a interpretação dos seus resultados específicos.