Complete Testing & Optimization Guide
Optimal ranges, provider comparison, and strategies to improve your eGFR (Estimated Glomerular Filtration Rate) levels
Included in 9 of 10 major testing providers
Kidney Function
>60 mL/min/1.73m², Normal:>90 mL/min/1.73m²
Abnormal eGFR (Estimated Glomerular Filtration Rate) levels can indicate underlying health issues that may go undetected without proper testing. Regular monitoring helps catch problems early when they're most treatable.
Understanding your eGFR (Estimated Glomerular Filtration Rate) levels enables targeted interventions, tracks treatment effectiveness, and helps optimize your overall health and performance.
eGFR (estimated Glomerular Filtration Rate) is the best overall measure of kidney function, estimating how much blood your kidneys filter per minute. GFR represents the volume of plasma your glomeruli (kidney filtering units) can clear of creatinine in one minute, adjusted for body surface area. Normal healthy kidneys filter about 90-120 mL of blood per minute per 1.73 m² of body surface area.
eGFR is calculated using serum creatinine, age, sex, and race through equations like CKD-EPI (most accurate) or MDRD. The calculation accounts for the fact that creatinine levels vary with muscle mass, age, and sex. eGFR is more accurate than creatinine alone for assessing kidney function because it normalizes for these variables. However, it can be inaccurate in extremes of muscle mass, rapidly changing kidney function, or certain ethnicities.
eGFR is used to stage chronic kidney disease (CKD) from Stage 1 (>90, normal or high) through Stage 5 (<15, kidney failure requiring dialysis). It guides treatment decisions, medication dosing, and timing of dialysis or transplant. Declining eGFR over time indicates progressive kidney disease, while stable eGFR suggests well-controlled kidney function or non-progressive disease.
Bottom line: TSH and Free T4 alone miss people with conversion problems. Free T3 is the only way to know if you have enough active thyroid hormone at the tissue level.
| Range Type | Level | Clinical Significance |
|---|---|---|
| Normal Kidney Function | >90 mL/min/1.73m² | Normal kidney function (CKD Stage 1 if kidney damage present, or normal if no damage markers). Kidneys filtering efficiently. However, some decline with age is normal—healthy 70-year-olds may have eGFR 60-80 without disease. If >90 with proteinuria or structural abnormalities, still classified as CKD Stage 1 requiring monitoring. |
| Mild Reduction (Stage 2 CKD) | 60-89 mL/min/1.73m² | Mild kidney dysfunction (CKD Stage 2). May be normal aging in elderly without other kidney damage. If under age 60 or accompanied by proteinuria, hypertension, or diabetes, indicates early CKD requiring treatment to prevent progression. Check urinalysis for protein/blood. Optimize blood pressure, glycemic control. Monitor every 6-12 months. Address cardiovascular risk factors aggressively. |
| Moderate Reduction (Stage 3 CKD) | 30-59 mL/min/1.73m² | Moderate kidney disease (Stage 3A if 45-59, Stage 3B if 30-44). Requires nephrology evaluation and active management. Start ACE inhibitor or ARB if proteinuria present. SGLT2 inhibitor if diabetic or high proteinuria. Adjust medication doses. Screen for anemia, bone disease, metabolic acidosis. Monitor every 3-6 months. Cardiovascular risk is significantly elevated—aggressive CV risk reduction essential. eGFR 30-45 (Stage 3B) requires preparation for potential dialysis/transplant. |
| Severe Reduction (Stage 4-5 CKD) | <30 mL/min/1.73m² | Advanced kidney disease. Stage 4 (eGFR 15-29):Severe CKD requiring urgent nephrology care, dialysis access planning, transplant evaluation. Manage complications (anemia, bone disease, acidosis, hyperkalemia). Protein restriction 0.6-0.8 g/kg. Monitor monthly. Stage 5 (eGFR <15):Kidney failure. Initiate dialysis when uremic symptoms develop or eGFR <10. Urgent transplant evaluation if candidate. Requires nephrologist management. |
Standard lab range:>60 mL/min/1.73m², Normal:>90 mL/min/1.73m²
ACE inhibitors or ARBs:First-line if proteinuria or diabetes. Reduce progression by 20-30%. May cause initial eGFR drop of 10-20% (acceptable unless >30% or hyperkalemia). Continue long-term
SGLT2 inhibitors:Empagliflozin, dapagliflozin, canagliflozin slow CKD progression by 30-40%, even in non-diabetics with eGFR as low as 20. Now standard of care for CKD with proteinuria
Blood pressure control:Target <130/80 mmHg (<120/80 if proteinuria >1g/day). Lower BP slows GFR decline significantly
Glycemic control:If diabetic, target HbA1c <7% (or <6.5% early in disease). Poor control accelerates kidney decline by 30-50%
Treat underlying cause:Address glomerulonephritis, obstruction, medication toxicity, autoimmune disease
Protein restriction:eGFR 30-60:limit to 0.8-1.0 g/kg daily. eGFR <30:restrict to 0.6-0.8 g/kg daily. Reduces uremic toxins and may delay dialysis
Sodium restriction:<2300 mg daily (<2000 mg if significant proteinuria or fluid retention). Reduces BP and proteinuria
Phosphate restriction:eGFR <45:limit to 800-1000 mg daily. Avoid processed foods, cola, dairy. Phosphate binders (calcium acetate, sevelamer) with meals
Potassium management:eGFR <30:often need to restrict high-K foods (bananas, oranges, tomatoes, potatoes) to prevent dangerous hyperkalemia
Adequate calories:Ensure 30-35 kcal/kg daily to prevent malnutrition during protein restriction
Dietitian consultation:Essential for CKD Stage 3-5 to balance restrictions with nutritional needs
Anemia (Hemoglobin <10 g/dL):Iron supplementation (oral or IV). ESAs (erythropoietin-stimulating agents) if iron-replete and Hgb <10. Target 10-11.5 g/dL
Bone and mineral disorder:Monitor calcium, phosphate, PTH, vitamin D. Vitamin D supplementation (cholecalciferol or active forms). Phosphate binders. Calcimimetics (cinacalcet) if high PTH
Metabolic acidosis (Bicarb <22):Sodium bicarbonate 650-1300 mg 2-3x daily slows CKD progression and reduces muscle wasting
Hyperkalemia (K+ >5.0):Low-potassium diet, patiromer or sodium zirconium cyclosilicate if persistent. Stop ACE/ARB only if severe (>6.0)
Fluid retention:Diuretics (furosemide for eGFR <30) for edema. Restrict sodium and fluids if necessary
CKD dramatically increases CV risk—eGFR 30-60 has 2-3x higher CV mortality. Aggressive risk factor management is critical:
Statin therapy:High-intensity statin for all CKD patients age 40-75. Reduces CV events by 25-30%
Aspirin:Consider low-dose (81 mg) if established CV disease, though bleeding risk higher in CKD
Blood pressure:Target <130/80. Use ACE/ARB as first-line
Lifestyle:Smoking cessation (critical), regular exercise (30+ min most days), Mediterranean diet
Diabetes control:Tight glycemic control reduces both kidney and cardiovascular complications
Nephrology referral:All patients with eGFR <30 need nephrology co-management. eGFR <20 requires urgent transplant/dialysis planning
Dialysis access:Place fistula or graft when eGFR 15-20 (takes 3-6 months to mature before use). Avoid peripherally inserted central catheters (PICCs) in non-dominant arm to preserve vessels
Transplant evaluation:Refer when eGFR <30 (or earlier if rapidly declining). Living donor transplant is ideal—can occur pre-emptively before dialysis
Dialysis education:Choose modality (hemodialysis vs peritoneal dialysis) based on lifestyle, access, and medical factors
Initiate dialysis:When eGFR <15 with uremic symptoms, volume overload, or refractory hyperkalemia/acidosis. Symptom-driven rather than eGFR-driven initiation is preferred
Note: Paradoxically, hyperfiltration in early diabetes predicts future kidney decline. If eGFR >120 in diabetic, intensify glycemic control and start ACE/ARB to prevent progression.
Note: Symptoms correlate with eGFR but vary by individual. Some tolerate eGFR 15-20 well;others symptomatic at 25-30. Uremic symptoms mandate dialysis regardless of eGFR. Monitor for hyperkalemia, acidosis, and fluid overload which are life-threatening.
The CKD-EPI equation (published 2009) is more accurate than the older MDRD equation, especially at eGFR >60 mL/min. CKD-EPI reduces overdiagnosis of CKD in elderly and better predicts outcomes. Most labs now use CKD-EPI as the standard. Both equations have limitations in extremes of body size, rapidly changing kidney function, and non-Black/White ethnicities.
Source:Levey AS, et al. A new equation to estimate glomerular filtration rate. Ann Intern Med. 2009;150(9):604-612.
KDIGO (Kidney Disease:Improving Global Outcomes) provides evidence-based guidelines for CKD staging, monitoring, and treatment. Key recommendations:Use eGFR + albuminuria for risk stratification. ACE/ARB for proteinuria. SGLT2 inhibitors for diabetic kidney disease. BP target <130/80. Statin for CV protection. Nephrology referral for eGFR <30 or rapidly declining. These guidelines form the foundation of CKD management worldwide.
Source:KDIGO 2012 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney Int Suppl. 2013;3(1):1-150.
SGLT2 inhibitors (empagliflozin, dapagliflozin, canagliflozin) reduce CKD progression by 30-40% in both diabetics and non-diabetics. The DAPA-CKD and EMPA-KIDNEY trials showed benefits even with eGFR as low as 20-25 mL/min. These drugs reduce proteinuria, slow eGFR decline, and lower risk of kidney failure requiring dialysis/transplant. Now considered standard of care for CKD with albuminuria.
Source:Heerspink HJL, et al. Dapagliflozin in patients with chronic kidney disease. N Engl J Med. 2020;383(15):1436-1446.
Normal age-related eGFR decline is ~1 mL/min/year after age 40. Decline >5 mL/min/year indicates progressive CKD requiring intervention. Rapid decline (>10 mL/min/year or >5 mL/min in 1 year) predicts high risk of kidney failure and warrants urgent nephrology referral to identify and treat reversible causes. Stable eGFR over years suggests well-controlled or non-progressive disease.
Source:Coresh J, et al. Decline in estimated glomerular filtration rate and subsequent risk of end-stage renal disease and mortality. JAMA. 2014;311(24):2518-2531.
CKD is an independent and powerful cardiovascular risk factor. Patients with eGFR 30-60 have 2-3x higher risk of CV death compared to eGFR >90. Patients with eGFR <30 are more likely to die from cardiovascular disease than to progress to dialysis. This underscores the critical importance of aggressive CV risk factor management (statins, BP control, diabetes management, smoking cessation) in all CKD patients.
Source:Go AS, et al. Chronic kidney disease and the risks of death, cardiovascular events, and hospitalization. N Engl J Med. 2004;351(13):1296-1305.
| Provider | Includes Test | Annual Cost | Total Biomarkers |
|---|---|---|---|
 Superpower | ✓ | $199 | 100+ |
 WHOOP Advanced Labs | ✓ | $349 | 65 |
 Labcorp OnDemand | ✓ | $398 | 30+ |
| ✓ | $486 | 40+ | |
| ✓ | $468 | 83 | |
| ✓ | $798 | 100+ | |
 InsideTracker | — | $680 | 48 |
 Function Health | ✓ | $499 | 100+ |
| ✓ | $900 | 70+ | |
| ✓ | $1150 | 110 | |
| — | $Varies | 75+ |
Choose from 9 providers that include this biomarker in their panels
eGFR (Estimated Glomerular Filtration Rate) is a kidney function biomarker that Measure of kidney function The normal reference range is >60 mL/min/1.73m², Normal:>90 mL/min/1.73m². Regular testing helps track changes and identify potential health issues early.
9 out of 10 major blood testing providers include eGFR (Estimated Glomerular Filtration Rate) in their standard panels. These include Superpower, Blueprint, Mito Health and others.
For most people, testing eGFR (Estimated Glomerular Filtration Rate) 2-4 times per year is recommended to establish baseline levels and track trends. If you have abnormal results or are actively working to optimize this biomarker, more frequent testing (quarterly) may be beneficial. Always consult with your healthcare provider for personalized testing frequency recommendations.
The standard laboratory reference range for eGFR (Estimated Glomerular Filtration Rate) is >60 mL/min/1.73m², Normal:>90 mL/min/1.73m². However, many functional medicine practitioners recommend tighter "optimal" ranges for peak health and performance. Your ideal range may vary based on your age, sex, health goals, and other individual factors. Work with a healthcare provider familiar with optimal ranges to determine your target levels.
Most direct-to-consumer blood testing services that include eGFR (Estimated Glomerular Filtration Rate) provide the physician order as part of their service. However, some states have restrictions on direct-to-consumer testing. Check with your chosen provider about availability in your state and whether they provide the necessary physician authorization.
Best overall indicator of kidney function. Values <60 indicate chronic kidney disease. Used to stage kidney disease and adjust medication dosing.
This information is for educational purposes only and is not medical advice. Always consult with a qualified healthcare provider about your specific health needs and before making decisions about blood testing.
