How can you diagnose DKD? Screening and diagnosis tests
Kidney damage in diabetic patients may or may not be due to DKD. The damage to the kidneys in a diabetic patient might be due to another cause and not directly to DKD.
In the absence of an established diagnosis, the evaluation of patients with diabetes and kidney disease should include investigation into the possible cause(s) and diabetic patients should be screened annually for kidney damage.
Screening tests should begin 5 years after the diagnosis in type 1 diabetic patients and from the moment of diagnosis in type 2 diabetic patients.
These screenings should include the following tests:
|Urine test to check for protein (albumin)
Damage to the filtration structures of the kidneys can lead to leaking proteins to the urine. Detection of these proteins in the urine can serve as a very good screening test to check for the health of the kidneys and the presence of DKD in diabetic patients.
A modest elevation of albumin (one of the most common proteins normally present in the blood) in the urine is known as “microalbuminuria” and can be associated with mild kidney damage but with greater risk of more severe kidney damage. “Macroalbuminuria”, a higher elevation of the concentration of albumin in the urine, is associated with a more severe kidney damage, a progressive decline in the kidneys’ function and a high risk of the kidneys failing.
|Albumin to creatinine ratio (ACR)
Measures the ratio of albumin and creatinine present in a spot urine sample.
Can determine the presence of microalbuminuria (ACR between 30-300 mg/g) and macroalbuminuria (ACR > 300 mg/g.)
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|Estimated Glomerular Filtration Rate (eGFR)
By using the blood creatinine concentration, age, body size and gender the doctor can calculate the eGFR for a patient.
The eGFR is the best test available to estimate the kidney function and to define the stage of the disease. It also allows for the monitoring of the disease progression and to plan it’s treatment accordingly.
Remember that the earlier the CKD is diagnosed the better the chances of slowing or stopping its progression.
The value of the eGFR decreases as kidney disease progresses: a lower eGFR score means that there is more damage to the kidneys and their function is lower.
The level of circulating creatinine in the blood is a marker for kidney function. Creatinine is a waste product from activities of muscle fibers, and is normally filtered and removed from the blood by the kidneys. When the kidneys function worsens the creatinine serum levels rise.
Serum creatinine is also used in the eGFR calculation.
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In most patients with diabetes, CKD should be attributable to diabetes (DKD) if:
• Macroalbuminuria is present;
• Microalbuminuria is present and at least one of the following:
> In the presence of diabetic retinopathy: that is a damage to the blood vessels in the retina of the eyes that can lead to visual impairment and loss of vision in diabetic patients,
> In a patient with type 1 diabetes of at least 10 years’ duration.
Kidney biopsy involves taking a sample of the tissue of 1 or both kidneys with a needle and examining it under a microscope. This is the most accurate test for diagnosing and confirming DKD in diabetic patients although is rarely necessary.
Findings in the kidney biopsy samples determine the grade or severity of the damage to the kidneys which is a direct reflection of the severity of the DKD.
In most cases though, careful screening of diabetic patients can identify people with DKD without the need for kidney biopsy.
Diabetes, DKD, and cardiovascular disease (CVD)
Since diabetes is also one of the most important CVD risk factors, patients with diabetes and DKD have a very high risk of heart conditions such as myocardial infarction and heart failure.
1. Radica Z. Alicic, Michele T. Rooney, Katherine R. Tuttle. CJASN Dec 2017, 12 (12) 2032-2045; DOI: 10.2215/CJN.11491116.
2. KDOQI. KDOQI Clinical Practice Guidelines and Clinical Practice Recommendations for Diabetes and Chronic Kidney Disease. Am J Kidney Dis 2007; 49:S12.
3. Diabetic Nephropathy: Diagnosis, Prevention, and Treatment. Jorge L. Gross, Mirela J. de Azevedo, Sandra P. Silveiro, Luís Henrique Canani, Maria Luiza Caramori, Themis Zelmanovitz. Diabetes Care Jan 2005, 28 (1) 164-176; DOI: 10.2337/diacare.28.1.164.
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