From the Guidelines
Initial diagnostic tests for suspected kidney dysfunction should include both urine albumin measurement and assessment of glomerular filtration rate (GFR) in individuals at risk for or with chronic kidney disease (CKD). This approach is supported by the KDIGO 2024 clinical practice guideline for the evaluation and management of chronic kidney disease 1. The guideline emphasizes the importance of early detection of CKD, as it allows for timely initiation of treatments that can reduce morbidity and mortality.
Key diagnostic tests for suspected kidney dysfunction include:
- Blood tests: serum creatinine, blood urea nitrogen (BUN), and estimated glomerular filtration rate (eGFR)
- Urine tests: urinalysis to detect protein, blood, glucose, or white blood cells, and a urine albumin-to-creatinine ratio to quantify protein excretion
- Imaging studies: ultrasound to evaluate kidney size, structure, and potential obstructions
These tests are crucial for early detection of kidney dysfunction, as kidney disease is often asymptomatic in its early stages. The combination of these tests provides a comprehensive assessment of kidney function, helping clinicians determine the cause and severity of kidney dysfunction and guide appropriate treatment. According to the KDIGO guideline, testing people at risk for and with CKD using both urine albumin measurement and assessment of GFR can help identify individuals with CKD and guide clinical decisions beyond initiating treatments specifically for CKD 1.
In addition to these tests, other studies have also emphasized the importance of screening for CKD in certain populations, such as those with diabetes or hypertension 1. The American Diabetes Association (ADA) and Kidney Disease: Improving Global Outcomes (KDIGO) recommend annual screening of patients with diabetes for CKD, and screening should start at diagnosis of type 2 diabetes or 5 years after diagnosis of type 1 diabetes 1.
Overall, the initial diagnostic tests for suspected kidney dysfunction should prioritize the assessment of GFR and urine albumin measurement, as recommended by the KDIGO 2024 guideline, to ensure early detection and timely treatment of CKD.
From the Research
Initial Diagnostic Tests for Suspected Kidney Dysfunction
The initial diagnostic tests for suspected kidney dysfunction include:
- Measurement of serum creatinine, blood urea nitrogen, and urine output 2
- Urinalysis with microscopy to check for proteinuria or hematuria 2
- Estimation of glomerular filtration rate (GFR) using methods such as inulin clearance, iothalamate clearance, or iohexol plasma clearance 3
- Screening for proteinuria using reagent test strips or quantitative measurements of marker proteins 3
Imaging Techniques
Imaging techniques such as ultrasound (US) can be used to evaluate kidney structure and function, including:
- Measuring longitudinal diameter and cortical thickness 4
- Evaluating renal echogenicity and urinary tract status 4
- Using color Doppler to show parenchymal perfusion and patency of veins and arteries 4
- Using spectral Doppler to diagnose renal artery stenosis and provide information about intrarenal microcirculation 4
Alternative Diagnostic Methods
Alternative diagnostic methods, such as salivary diagnostics, can be used to assess dialysis need in renal failure patients, including:
- Measuring salivary creatinine, urea, and potassium levels 5
- Correlating salivary and serum levels of these markers to diagnose renal failure 5
Limitations of Serum Creatinine as a Screening Test
Serum creatinine is an inadequate screening test for renal failure in elderly patients due to: