Screen for Kidney Disease

Introduction

Think of your kidneys as your body's silent filtration system. They work tirelessly, often without causing any symptoms, even when they start to struggle. Kidney diseases, especially Chronic Kidney Disease (CKD), are often called "silent" because damage can happen gradually over years before you feel unwell. Screening is like an early warning system. It uses simple tests to find kidney problems before they cause serious damage or symptoms, allowing for earlier and more effective treatment . ^{1 2}

Who Should Get Screened for Kidney Disease? ^{1 3 4}

Not everyone needs regular kidney screening. Doctors focus on people who have a higher risk of developing kidney problems. You should talk to your doctor about screening if you have any of these conditions or risk factors:

• 1. Diabetes: This is the No 1 cause of kidney failure. High blood sugar can damage the kidney's delicate filters over time.
• 2. High Blood Pressure (Hypertension): The No 2 cause. High pressure strains the blood vessels in the kidneys.
• 3. Heart Disease (Cardiovascular Disease): Heart and kidney health are closely linked.
• 4. Family History: Having a close relative (parent, sibling, child) with kidney failure.
• 5. Age 60 or Older: Kidney function naturally declines slightly with age.
• 6. History of Acute Kidney Injury (AKI): A previous sudden episode of kidney damage increases future risk.
• 7. Long-Term Use of Certain Medications: Especially frequent or high-dose use of painkillers like NSAIDs (ibuprofen, naproxen).
• 8. Obesity: Increases the risk of diabetes and high blood pressure.
• 9. Belonging to Certain Ethnic Groups: Higher rates of kidney disease are seen in people of African, Hispanic, Asian, Pacific Islander, or Aboriginal/Indigenous descent.
• 10. Autoimmune Diseases: Conditions like Lupus (SLE) can affect the kidneys.
• 11. History of Kidney Stones or Enlarged Prostate: These can cause blockages or repeated infections.

What Screening Tests Are Used? ^{1 2 5}

Screening is simple and usually involves two main tests, often done together:

• 1. Blood Test: Estimated Glomerular Filtration Rate (eGFR)
  • What it measures: How well your kidneys are filtering waste from your blood. It estimates the rate based on a blood creatinine level (a waste product), your age, sex, and sometimes race.
  • What the numbers mean : ⁶

    Stage of CKD	eGFR result	What it means
    Stage 1	90 or higher	Mild kidney damage Kidneys work as well as normal
    Stage 2	60–89	Mild kidney damage Kidneys still work well
    Stage 3a	45–59	Mild to moderate kidney damage Kidneys don’t work as well as they should
    Stage 3b	30–44	Moderate to severe damage Kidneys don’t work as well as they should
    Stage 4	15–29	Severe kidney damage Kidneys are close to not working at all
    Stage 5	less than 15	Most severe kidney damage Kidneys are very close to not working or have stopped working (failed)

  • Why it's important: It's the best overall measure of how well your kidneys are working.
• 2. Urine Test: Albumin-to-Creatinine Ratio (ACR)
  • What it measures: Checks if there's a small amount of a protein called albumin leaking into your urine. Healthy kidneys keep albumin in your blood.
  • What the numbers mean:
    • ACR less than 30 mg/g: Normal (little or no albumin).
    • ACR 30-300 mg/g: Moderately increased albumin ("microalbuminuria") - an early sign of kidney damage.
    • ACR over 300 mg/g: Severely increased albumin ("macroalbuminuria") - significant kidney damage.
  • Why it's important: Albumin in the urine is often the earliest sign of kidney damage, especially from diabetes or high blood pressure. It can appear before the eGFR drops significantly.

How Often Should You Be Screened? ^{1 3 4}

This depends entirely on your risk factors:

• People with Diabetes or High Blood Pressure: Should have both eGFR and ACR tests at least once a year , often as part of their regular check-up.
• People with other risk factors (like heart disease, family history, age 60+): Should discuss screening with their doctor. Yearly testing is common, but your doctor will advise based on your specific situation.
• People with no risk factors: Routine screening is generally not recommended unless symptoms develop.

What Happens if My Screening Test is Abnormal?

Don't panic. An abnormal result doesn't always mean you have serious kidney disease. It means your doctor needs to investigate further. Here’s what might happen next^{2 7}

• 1. Repeat Tests: Kidney function can vary slightly. Your doctor may repeat the tests to confirm the results.
• 2. Review Your History: They'll ask more about your health, medications, and family.
• 3. Look for the Cause: They'll investigate why the test is abnormal (e.g., checking diabetes/hypertension control).
• 4. Additional Tests: These might include:
  • More detailed urine tests.
  • Imaging tests like an ultrasound to look at kidney structure.
  • Sometimes, blood tests for specific causes.
• 5. Develop a Plan: If kidney disease is confirmed, your doctor will work with you on a management plan. This could include:
  • Better control of blood pressure or diabetes.
  • Medications to protect the kidneys (like ACE inhibitors or ARBs).
  • Dietary changes (e.g., limiting salt, protein).
  • Lifestyle changes (e.g., stopping smoking, healthy weight).
  • More frequent monitoring.

Key Benefits of Early Detection through Screening:

• Slows or Stops Progression: Treatment started early is much more effective at preventing CKD from worsening.
• Reduces Complications: Lowers the risk of heart disease, stroke, and other problems linked to kidney disease.
• Delays or Prevents Kidney Failure: Avoiding the need for dialysis or a transplant.
• Improves Overall Health: Managing kidney disease helps your whole body.

Key Takeaways

• Kidney disease is often silent. Screening finds problems before symptoms start.
• If you have diabetes, high blood pressure, or other risk factors, yearly screening is vital.
• Screening is simple: A blood test (eGFR) and a urine test (ACR).
• Finding kidney disease early gives you and your doctor the best chance to protect your kidneys.
• Talk to your doctor: Ask if and when you should be screened based on your personal health.

References

1. 1. Kidney Disease: Improving Global Outcomes (KDIGO). KDIGO 2012 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney Int Suppl. 2013;3(1):1-150.
2. 2. National Kidney Foundation. CKD Screening and Awareness: Key Facts. https://www.kidney.org/news/newsroom/factsheets/CKD-Screening-and-Awareness (Accessed October 26, 2023)
3. 3. American Diabetes Association. 11. Microvascular Complications and Foot Care: Standards of Medical Care in Diabetes—2023. Diabetes Care. 2023;46(Suppl 1):S191-S202.
4. 4. Whelton PK, Carey RM, Aronow WS, et al. 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA Guideline for the Prevention, Detection, Evaluation, and Management of High Blood Pressure in Adults. J Am Coll Cardiol. 2018;71(19):e127-e248.
5. 5. Levey AS, Inker LA, Coresh J. GFR estimation: from physiology to public health. Am J Kidney Dis. 2014;63(5):820-834.
6. 6. https://www.kidneyfund.org/all-about-kidneys/stages-kidney-disease
7. 7. National Institute for Health and Care Excellence (NICE). Chronic kidney disease: assessment and management. NICE guideline [NG203]. Published 25 August 2021.