Excellent 4.6 out of 5
Renal and Electrolyte Disorders

Blood Testing for Acute Kidney Injury

Early blood testing for Acute Kidney Injury identifies declining filtration before symptoms, protecting whole‑body balance. Superpower offers Creatinine, eGFR, BUN, and BUN/Creatinine Ratio testing. Access in‑clinic or at‑home options; home collection for AKI testing is available in New York and California.

Book a blood Acute Kidney Injury test
Cancel anytime
HSA/FSA eligible
Results in a week
Physician reviewed

Every result is checked

·
CLIA-certified labs

Federal standard for testing

·
HIPAA compliant

Your data is 100% secure

Key Benefits

  • Check kidney filtration now and flag acute kidney injury using creatinine, eGFR, and BUN.
  • Spot early kidney stress and flag when rapid, urgent care is needed.
  • Distinguish low blood flow problems from kidney tissue injury using BUN/Creatinine ratio.
  • Clarify dehydration versus blockage to direct fluids or imaging promptly.
  • Guide safe medication dosing and avoid kidney-harming drugs, contrast dyes, and NSAIDs.
  • Protect pregnancy by detecting filtration changes tied to preeclampsia and medication safety needs.
  • Track recovery after illness, surgery, infection, or contrast exposure to ensure kidneys rebound.
  • Interpret results best with urine output, urinalysis, prior creatinine, and symptoms context.

What are Acute Kidney Injury biomarkers?

Acute kidney injury (AKI) biomarkers are molecules in the blood that signal how well the kidneys are filtering and whether their cells are under stress or damaged. They let clinicians detect a sudden drop in kidney function quickly and understand what kind of problem is unfolding. Some biomarkers reflect filtration—the kidney’s sieving job—such as creatinine (a muscle byproduct), urea nitrogen (BUN), and cystatin C (a small protein made steadily by most cells). Others reflect injury inside the kidney’s tubules, the tiny pipes that process filtered fluid. These include NGAL (neutrophil gelatinase–associated lipocalin), which is released by stressed tubular cells, and proenkephalin A (penKid), a stable fragment that tracks real-time filtering capacity. Beta-2 microglobulin (β2M) can also indicate changes in filtration and tubular handling. Together, these blood signals help distinguish poor filtration from direct tubular injury, reveal AKI earlier than symptoms, and support timely decisions about fluids, medicines, and when to protect the kidneys from further harm.

Why is blood testing for Acute Kidney Injury important?

Acute Kidney Injury is a sudden fall in kidney filtration. Blood tests—creatinine, eGFR, BUN, and the BUN/creatinine ratio—reveal this shift early and show how it ripples through fluid balance, electrolytes, acid–base control, and toxin clearance across the heart, brain, lungs, and muscles.Typical ranges: creatinine 0.6–1.2 (optimal low‑normal for your muscle mass; higher baselines in men, lower in women and children). eGFR is healthiest at 90 or higher; drops track AKI. BUN 7–20, most steady mid‑range when hydrated. BUN/creatinine ratio 10–20; higher suggests reduced kidney blood flow, while normal‑to‑low with rising creatinine points to intrinsic injury. When filtration falls, creatinine and BUN rise, eGFR falls, and urine output drops with swelling, nausea, confusion, breathlessness, and sometimes high potassium.Low values can mislead. Low creatinine reflects low muscle mass, pregnancy, or childhood; AKI can still exist if that “normal” number is a sharp rise from baseline. Low BUN occurs with low protein intake, liver dysfunction, or excess water; a low ratio plus rising creatinine leans toward tubular damage. Older adults often show confusion; children decompensate faster with fluid shifts; in pregnancy, even small creatinine increases are concerning.Big picture: these markers integrate kidney work with circulation, hormones, and metabolism. Watching their trends links kidney health to heart rhythm, blood pressure, brain clarity, and recovery after illness, and helps forecast long‑term risk of chronic kidney disease.

What insights will I get?

Acute Kidney Injury (AKI) blood testing is essential because the kidneys play a central role in filtering waste, balancing fluids, and regulating blood pressure—functions that impact energy, metabolism, cardiovascular health, cognition, and immunity. When kidney function is disrupted, waste products can build up quickly, affecting nearly every system in the body. At Superpower, we assess AKI risk and status using four key biomarkers: Creatinine, estimated Glomerular Filtration Rate (eGFR), Blood Urea Nitrogen (BUN), and the BUN/Creatinine Ratio.Creatinine is a waste product from muscle metabolism, and its blood level rises when the kidneys are not filtering efficiently. eGFR is a calculated value that estimates how well the kidneys are clearing creatinine from the blood, providing a direct measure of kidney filtration capacity. BUN reflects the amount of nitrogen in the blood from urea, another waste product filtered by the kidneys. The BUN/Creatinine Ratio helps distinguish between different causes of kidney dysfunction, such as dehydration versus direct kidney injury.Together, these markers reveal how stable and effective your kidneys are at maintaining internal balance. Healthy values suggest the kidneys are efficiently clearing waste and supporting overall system stability. Abnormal results may indicate acute stress or injury to the kidneys, which can disrupt fluid, electrolyte, and toxin balance, with downstream effects on heart, brain, and immune function.Interpretation of these biomarkers can be influenced by factors such as age, pregnancy, muscle mass, recent illness, certain medications, and laboratory assay differences. These variables are important to consider for accurate assessment of kidney health.

Superpower also tests for

See more diseases

Frequently Asked Questions About

What is Acute Kidney Injury blood testing?

Acute Kidney Injury is a sudden drop in kidney filtering over hours to days. Blood testing looks for that loss by measuring creatinine (muscle waste), estimating GFR (eGFR), measuring blood urea nitrogen (BUN), and calculating the BUN/creatinine ratio to hint at cause and severity. Superpower tests your blood for Creatinine, eGFR, BUN, and the BUN/Creatinine Ratio. These markers rise or fall as kidneys fail to clear waste and regulate fluid and acid-base balance. The panel complements clinical findings like urine output and blood pressure but often gives the earliest, objective signal that the kidneys are under stress.

Why should I get Acute Kidney Injury blood testing?

AKI can be silent but life-threatening. Early shifts in creatinine, eGFR, BUN, and the BUN/creatinine ratio flag reduced filtration and perfusion before symptoms are obvious. Testing is critical if you’re acutely ill, dehydrated, recently had surgery, received IV contrast, or started kidney-stressing medicines. If you have diabetes, hypertension, heart failure, or known kidney disease, results guide triage, fluid status assessment, and medication decisions. In plain terms: it tells us how hard your kidneys are working right now, whether the problem is low flow (prerenal) or intrinsic injury, and how quickly it’s changing.

Can I get a blood test at home?

Yes. With Superpower, our team member can organize a blood draw in your home.

How often should I test?

For suspected AKI, test promptly and trend the change—typically repeat within 24–48 hours, and sooner if levels are rapidly changing or urine output falls. After exposure to potential kidney stressors (major illness, surgery, IV contrast, new nephrotoxic drugs), check within the first 24–72 hours. If you’re stable and low risk, these markers are usually included with routine annual labs. If you have chronic kidney disease or high risk, monitoring is more frequent around clinical events. In AKI, the trajectory over time matters more than a single value.

What can affect biomarker levels?

Hydration and perfusion status strongly sway BUN, creatinine, and their ratio. Muscle mass, recent strenuous exercise, and high meat or creatine intake raise creatinine independent of kidney function. Catabolic states, gastrointestinal bleeding, corticosteroids, and tetracyclines elevate BUN. Medications that reduce filtration or alter tubular secretion—NSAIDs, ACE inhibitors/ARBs, diuretics, trimethoprim, cimetidine—can raise creatinine. Recent iodinated contrast can trigger AKI. Pregnancy lowers baseline creatinine. Age and sex affect eGFR estimates, and eGFR is unreliable when kidney function is changing rapidly (non–steady state).

Are there any preparations needed before the blood test for Creatinine, eGFR, BUN, BUN/Creatinine Ratio?

No special fasting is required for Creatinine, eGFR, BUN, or the BUN/Creatinine Ratio. Aim for usual hydration; avoid deliberate over- or under-drinking before the draw. Skip heavy meat meals, protein shakes, or creatine supplements the day before, and avoid strenuous exercise for 24 hours, as these can transiently raise creatinine and BUN. If safe, note the timing of medications that affect creatinine secretion (for example, trimethoprim or cimetidine) and any recent IV contrast. A morning sample helps with consistency, but timing is less critical than getting tested promptly when AKI is suspected.

Can lifestyle changes affect my biomarker levels?

Yes, but mostly at the margins. Hydration status and protein intake can shift BUN and the BUN/creatinine ratio; muscle mass and supplements can change creatinine. Avoiding kidney stressors (nephrotoxins, dehydration) lowers AKI risk. That said, abnormal results usually reflect true kidney physiology, not just lifestyle. Short-term changes can move numbers without fixing the cause. If values are outside your baseline or trending worse, the priority is medical evaluation and addressing the underlying process.

How do I interpret my results?

Look at the change from your baseline and the pace. A creatinine rise ≥0.3 mg/dL in 48 hours or ≥1.5× baseline within 7 days meets AKI criteria (KDIGO). eGFR >90 is normal; <60 suggests impaired filtration, but eGFR is less accurate during acute changes. Typical BUN is about 7–20 mg/dL; higher values reflect reduced clearance or increased production. A BUN/creatinine ratio of ~10–20 is usual; >20 suggests prerenal states (low kidney blood flow), whereas a lower ratio with rising creatinine points toward intrinsic kidney injury or low urea production. Always interpret alongside symptoms and urine output.

How it works

1

Test your whole body

Get a comprehensive blood draw at one of our 3,000+ partner labs or from the comfort of your own home.

2

An Actionable Plan

Easy to understand results & a clear action plan with tailored recommendations on diet, lifestyle changes, supplements and pharmaceuticals.

3

A Connected Ecosystem

You can book additional diagnostics, buy curated supplements for 20% off & pharmaceuticals within your Superpower dashboard.

Superpower tests more than 
100+ biomarkers & common symptoms

Developed by world-class medical professionals

Supported by the world’s top longevity clinicians and MDs.

Dr Anant Vinjamoori

Superpower Chief Longevity Officer, Harvard MD & MBA

A smiling woman wearing a white coat and stethoscope poses for a portrait.

Dr Leigh Erin Connealy

Clinician & Founder of The Centre for New Medicine

Man in a black medical scrub top smiling at the camera.

Dr Abe Malkin

Founder & Medical Director of Concierge MD

Dr Robert Lufkin

UCLA Medical Professor, NYT Bestselling Author

membership

$17

/month
Billed annually at $199
A smartphone displays health app results, showing biomarker summary, superpower score, and biological age details.
A website displays a list of most ordered products including a ring, vitamin spray, and oil.
A smartphone displays health app results, showing biomarker summary, superpower score, and biological age details.A tablet screen shows a shopping website with three most ordered products: a ring, supplement, and skincare oil.
What could cost you $15,000 is $199

Superpower
Membership

Your membership includes one comprehensive blood draw each year, covering 100+ biomarkers in a single collection
One appointment, one draw for your annual panel.
100+ labs tested per year
A personalized plan that evolves with you
Get your biological age and track your health over a lifetime
$
17
/month
billed annually
Flexible payment options
Four credit card logos: HSA/FSA Eligible, American Express, Visa, and Mastercard.
Start testing
Cancel anytime
HSA/FSA eligible
Results in a week
Pricing may vary for members in New York and New Jersey **

Finally, healthcare that looks at the whole you