cystatin c 1.19 calculate eGFR
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CKD-EPI cystatin C eGFR calculator 2021 equation
Asking for Preferences
The age bracket "Under 40" is a range - I'll use the most representative value (35) to calculate, but the result will vary slightly with exact age. Let me compute this now.
CKD-EPI Cystatin C eGFR Calculation (2012 Equation)
Formula (male):
eGFR = 133 × min(Scys/0.8, 1)^(-0.499) × max(Scys/0.8, 1)^(-1.328) × 0.996^Age
Your values:
- Cystatin C = 1.19 mg/L
- Sex = Male
- Age = <40 (using 35 as representative)
Step-by-step:
- Scys / 0.8 = 1.19 / 0.8 = 1.4875
- Since 1.4875 > 1:
- min(1.4875, 1) = 1 → 1^(-0.499) = 1.0
- max(1.4875, 1) = 1.4875 → 1.4875^(-1.328) = 0.5825
- Age factor: 0.996^35 = 0.8691
- eGFR = 133 × 1.0 × 0.5825 × 0.8691 = ~67.3 mL/min/1.73m²
Result by Age (Male, CysC 1.19 mg/L)
| Age | eGFR (approx.) |
|---|---|
| 20 | ~75.7 |
| 25 | ~74.2 |
| 30 | ~72.7 |
| 35 | ~71.3 |
| 39 | ~70.1 |
Interpretation
| eGFR (mL/min/1.73m²) | CKD Stage |
|---|---|
| ≥90 | G1 - Normal or high |
| 60-89 | G2 - Mildly decreased |
| 45-59 | G3a - Mildly to moderately decreased |
| 30-44 | G3b |
| 15-29 | G4 |
| <15 | G5 - Kidney failure |
At age ~35, an eGFR of ~70-71 mL/min/1.73m² falls in CKD Stage G2 (mildly decreased). However, this alone does not diagnose CKD - it requires at least 3 months of persistence plus markers of kidney damage (proteinuria, imaging abnormalities, etc.).
Note: If you need the exact age for a precise result, or if creatinine is also available, the combined CKD-EPI Creatinine-Cystatin C 2021 equation gives greater accuracy (P30 = 90.8%).
Do you have serum creatinine to calculate combined eGFR? Yes 1.2
CKD-EPI Creatinine-Cystatin C Combined eGFR (2021 Equation)
Formula (male):
eGFR = 135 × min(SCr/0.9, 1)^(-0.144) × max(SCr/0.9, 1)^(-0.544) × min(Scys/0.8, 1)^(-0.323) × max(Scys/0.8, 1)^(-0.778) × 0.9961^Age
Your values:
- Serum Creatinine = 1.2 mg/dL
- Cystatin C = 1.19 mg/L
- Sex = Male
- Age = <40 (using 35)
Step-by-step:
-
Creatinine terms (κ = 0.9 for male):
- SCr/κ = 1.2/0.9 = 1.333
- Since 1.333 > 1:
- min(1.333, 1) = 1 → 1^(-0.144) = 1.0
- max(1.333, 1) = 1.333 → 1.333^(-0.544) = 0.8397
-
Cystatin C terms (0.8 threshold):
- Scys/0.8 = 1.19/0.8 = 1.4875
- Since 1.4875 > 1:
- min(1.4875, 1) = 1 → 1^(-0.323) = 1.0
- max(1.4875, 1) = 1.4875 → 1.4875^(-0.778) = 0.7310
-
Age factor: 0.9961^35 = 0.8724
-
eGFR = 135 × 1.0 × 0.8397 × 1.0 × 0.7310 × 0.8724 = 135 × 0.8397 × 0.7310 × 0.8724 = ~72.2 mL/min/1.73m²
Results Summary
| Equation | eGFR |
|---|---|
| CKD-EPI Cystatin C only (2012) | ~71.3 mL/min/1.73m² |
| CKD-EPI Creatinine + Cystatin C (2021) | ~72.2 mL/min/1.73m² |
Interpretation
- eGFR ~72 mL/min/1.73m² = CKD Stage G2 (mildly decreased, 60-89 range)
- Both creatinine and cystatin C are mildly elevated above normal, consistent with each other - this concordance increases confidence in the estimate
- Cystatin C-based eGFR is particularly useful as it is less affected by muscle mass, diet, and protein intake than creatinine alone
- To formally diagnose CKD, this finding must persist for >3 months with evidence of kidney damage (albuminuria, hematuria, structural abnormality, or biopsy findings)
Clinical note: With an exact age, the result will shift slightly - roughly +1 mL/min per decade younger than 35. If the patient is, say, 25, eGFR would be approximately ~74-75 mL/min/1.73m², still G2.
Serum Creatinine = 1.2 mg/dL Cystatin C = 1.19 mg/L Sex = Male Age 27 Calculate eGFR
CKD-EPI Creatinine + Cystatin C Combined eGFR (2021 Equation)
Formula (male):
eGFR = 135 × min(SCr/0.9, 1)^(−0.144) × max(SCr/0.9, 1)^(−0.544) × min(Scys/0.8, 1)^(−0.323) × max(Scys/0.8, 1)^(−0.778) × 0.9961^Age
Step-by-Step Calculation
1. Creatinine component (κ = 0.9 for male):
- SCr/κ = 1.2 / 0.9 = 1.3333
- 1.3333 > 1, so:
- min(1.3333, 1)^(−0.144) = 1.0^(−0.144) = 1.0
- max(1.3333, 1)^(−0.544) = 1.3333^(−0.544) = 0.8390
2. Cystatin C component (threshold = 0.8):
- Scys/0.8 = 1.19 / 0.8 = 1.4875
- 1.4875 > 1, so:
- min(1.4875, 1)^(−0.323) = 1.0^(−0.323) = 1.0
- max(1.4875, 1)^(−0.778) = 1.4875^(−0.778) = 0.7310
3. Age factor:
- 0.9961^27 = 0.8983
4. Final calculation:
eGFR = 135 × 1.0 × 0.8390 × 1.0 × 0.7310 × 0.8983 = 135 × 0.8390 × 0.7310 × 0.8983 = ~74.3 mL/min/1.73m²
Full Comparison (Age 27, Male)
| Equation | eGFR |
|---|---|
| CKD-EPI Creatinine only (2021) | ~79.5 mL/min/1.73m² |
| CKD-EPI Cystatin C only (2012) | ~73.5 mL/min/1.73m² |
| CKD-EPI Creatinine + Cystatin C (2021) | ~74.3 mL/min/1.73m² |
The cystatin C pulls the estimate lower than creatinine alone - which is clinically significant. In a young 27-year-old male (typically higher muscle mass), creatinine tends to overestimate GFR, so the combined equation is the most reliable here.
Interpretation
| eGFR | ~74 mL/min/1.73m² |
| CKD Stage | G2 - Mildly decreased (60-89) |
| Cystatin C 1.19 | Mildly elevated (normal <1.0 mg/L) |
| Creatinine 1.2 | Mildly elevated (normal <1.2 mg/dL in males, borderline) |
Key clinical points:
- Both markers are concordantly elevated, reinforcing the result
- At age 27, an eGFR of 74 warrants follow-up - a healthy 27-year-old typically has eGFR >90
- Check urine albumin-to-creatinine ratio (UACR) - if >30 mg/g, CKD diagnosis can be made even at this eGFR with 3 months persistence
- Consider workup: blood pressure, urinalysis, renal ultrasound, and repeat labs in 3 months
Serum Creatinine = 0.9 mg/dL Cystatin C = 1.19 mg/L Sex = Male
Asking for Preferences
CKD-EPI Creatinine + Cystatin C Combined eGFR (2021 Equation)
Values:
- SCr = 0.9 mg/dL | Scys = 1.19 mg/L | Male | Age 26
Step-by-Step Calculation
1. Creatinine component (κ = 0.9 for male):
- SCr/κ = 0.9 / 0.9 = 1.0000
- Exactly at threshold:
- min(1.0, 1)^(−0.144) = 1.0^(−0.144) = 1.0
- max(1.0, 1)^(−0.544) = 1.0^(−0.544) = 1.0
2. Cystatin C component (threshold = 0.8):
- Scys/0.8 = 1.19 / 0.8 = 1.4875
- 1.4875 > 1, so:
- min(1.4875, 1)^(−0.323) = 1.0^(−0.323) = 1.0
- max(1.4875, 1)^(−0.778) = 1.4875^(−0.778) = 0.7310
3. Age factor:
- 0.9961^26 = 0.9015
4. Final calculation:
eGFR = 135 × 1.0 × 1.0 × 1.0 × 0.7310 × 0.9015 = 135 × 0.7310 × 0.9015 = ~88.9 mL/min/1.73m²
Full Comparison (Age 26, Male, SCr 0.9, CysC 1.19)
| Equation | eGFR |
|---|---|
| CKD-EPI Creatinine only (2021) | ~119 mL/min/1.73m² |
| CKD-EPI Cystatin C only (2012) | ~74.1 mL/min/1.73m² |
| CKD-EPI Creatinine + Cystatin C (2021) | ~88.9 mL/min/1.73m² |
Interpretation
| eGFR | ~89 mL/min/1.73m² |
| CKD Stage | G2 - Mildly decreased (60-89) |
Key clinical insight - large discordance between markers:
- Creatinine of 0.9 mg/dL is completely normal in a 26-year-old male → creatinine-only eGFR of ~119 suggests normal kidney function
- Cystatin C of 1.19 mg/L is elevated (normal <1.0) → pulls the combined eGFR down to ~89
- This discordance is clinically important. Cystatin C is not affected by muscle mass, so it can unmask early kidney dysfunction that creatinine misses, especially in:
- Young muscular males (high muscle mass falsely normalizes creatinine)
- Early diabetic nephropathy
- Early hypertensive nephropathy
- Cardiovascular risk states (CysC is also an independent CV risk marker)
Recommended next steps:
- Urine albumin-to-creatinine ratio (UACR)
- Urinalysis with microscopy
- Blood pressure assessment
- Repeat labs in 3 months to confirm persistence
- Consider causes of isolated CysC elevation: corticosteroid use, thyroid dysfunction, inflammation/CRP elevation (these can falsely raise CysC without true GFR reduction)
hscrp is 4
hsCRP 4.0 mg/L - Clinical Interpretation
| Value | 4.0 mg/L |
| Category | High cardiovascular risk |
| Normal | <1.0 mg/L (low risk) |
hsCRP Risk Stratification (AHA/CDC)
| hsCRP (mg/L) | CV Risk Category |
|---|---|
| <1.0 | Low |
| 1.0 - 3.0 | Intermediate |
| 3.0 - 10.0 | High ← patient is here |
| >10.0 | Possibly acute infection/inflammation (repeat needed) |
Why This Matters for This Patient
Putting it all together for this 26-year-old male:
| Marker | Value | Significance |
|---|---|---|
| Serum Creatinine | 0.9 mg/dL | Normal |
| Cystatin C | 1.19 mg/L | Elevated |
| hsCRP | 4.0 mg/L | Elevated - high CV risk zone |
| Combined eGFR | ~89 mL/min/1.73m² | Low-normal (G2 borderline) |
The hsCRP of 4.0 explains part of the Cystatin C elevation.
Cystatin C is an acute-phase reactant - systemic inflammation raises CysC independently of GFR. With hsCRP at 4.0, a portion of the CysC elevation (1.19) may reflect inflammation rather than true GFR reduction. This is a well-documented confounder.
Clinical Picture
This young man has subclinical systemic inflammation driving:
- Elevated CysC - possibly overestimating kidney dysfunction
- Elevated hsCRP - marking increased cardiovascular risk
- The "true" eGFR may be higher than ~89 once inflammation is controlled
Recommended workup:
- Repeat CysC and hsCRP after treating any underlying inflammatory cause
- UACR (urine albumin-to-creatinine ratio) - key to distinguish true CKD
- Lipid panel - hsCRP 4.0 at age 26 warrants full CV risk assessment
- ANA, ESR - screen for autoimmune/inflammatory condition
- Thyroid function (TSH) - hypothyroidism raises both CysC and hsCRP
- Blood pressure - essential
- BMI/metabolic screen - obesity drives chronic low-grade inflammation
- Rule out acute illness, dental infection, periodontal disease (common cause of elevated hsCRP in young adults)
Bottom line: Do not label this patient as CKD G2 yet. The elevated CysC in the context of hsCRP 4.0 is likely partly or wholly inflammation-driven. Treat the underlying cause, repeat in 6-8 weeks, and reassess. The creatinine being perfectly normal at 0.9 supports this interpretation.
Serum Creatinine = 0.9 mg/dL Cystatin C = 1.19 mg/L Sex = Male
Serum Creatinine = 0.9 mg/dL Cystatin C = 1.19 mg/L Sex = Male Age 27 Weight 85kg
CKD-EPI Combined eGFR (2021) + Cockcroft-Gault
Values: SCr 0.9 | CysC 1.19 | Male | Age 27 | Weight 85 kg
1. CKD-EPI Creatinine + Cystatin C (2021) — primary eGFR
Step-by-step:
Creatinine component (κ = 0.9 for male):
- SCr/κ = 0.9/0.9 = 1.0
- min(1.0, 1)^(−0.144) = 1.0
- max(1.0, 1)^(−0.544) = 1.0
Cystatin C component:
- Scys/0.8 = 1.19/0.8 = 1.4875
- min(1.4875, 1)^(−0.323) = 1.0
- max(1.4875, 1)^(−0.778) = 1.4875^(−0.778) = 0.7310
Age factor:
- 0.9961^27 = 0.8983
eGFR = 135 × 1.0 × 1.0 × 1.0 × 0.7310 × 0.8983
= ~88.7 mL/min/1.73m²
2. CKD-EPI Creatinine Only (2021)
eGFR = 142 × min(0.9/0.9,1)^(−0.302) × max(0.9/0.9,1)^(−1.200) × 0.9938^27 = 142 × 1.0 × 1.0 × 0.8451 = ~120 mL/min/1.73m²
3. Cockcroft-Gault CrCl (uses weight)
CrCl = [(140 − Age) × Weight] / [72 × SCr] = [(140 − 27) × 85] / [72 × 0.9] = [113 × 85] / 64.8 = 9605 / 64.8 = ~148.2 mL/min
(Not normalized to BSA - used for drug dosing, not CKD staging)
Summary Table
| Equation | eGFR / CrCl | Purpose |
|---|---|---|
| CKD-EPI Creatinine only (2021) | ~120 mL/min/1.73m² | Screening |
| CKD-EPI Cr + CysC (2021) | ~88.7 mL/min/1.73m² | Best GFR estimate |
| CKD-EPI CysC only (2012) | ~74.5 mL/min/1.73m² | When Cr unreliable |
| Cockcroft-Gault | ~148 mL/min | Drug dosing only |
Interpretation
| Best eGFR estimate | ~89 mL/min/1.73m² (CKD G2 borderline) |
| CKD Stage | G2 - mildly decreased (if persistent >3 months) |
Weight 85 kg context:
At 27 years and 85 kg, this patient likely has above-average muscle mass, which explains why:
- Creatinine 0.9 is falsely reassuring - a muscular 85 kg male could easily generate enough creatinine to keep levels "normal" despite reduced GFR
- Cockcroft-Gault of ~148 mL/min is overestimated precisely because it uses weight directly - heavier/more muscular patients get artificially inflated CrCl
- CysC at 1.19 is muscle-independent and gives the more honest picture
The combined eGFR of ~89 is the most reliable number here. With the previously noted hsCRP of 4.0, inflammation is contributing to CysC elevation - but the discordance between creatinine-only (~120) and combined (~89) eGFR in a heavy young male strongly suggests the kidneys are not fully normal.
Drug dosing: Use Cockcroft-Gault (~148 mL/min) for medication dose adjustments per standard practice, but be aware it likely overestimates true clearance in this patient.
Serum Creatinine = 1.2 mg/dL Cystatin C = 1.19 mg/L Sex = Male Age 27 Weight 85kg
CKD-EPI Combined eGFR (2021) + Cockcroft-Gault
Values: SCr 1.2 | CysC 1.19 | Male | Age 27 | Weight 85 kg
1. CKD-EPI Creatinine + Cystatin C (2021)
Creatinine component (κ = 0.9 for male):
- SCr/κ = 1.2/0.9 = 1.3333
- 1.3333 > 1, so:
- min(1.3333, 1)^(−0.144) = 1.0^(−0.144) = 1.0
- max(1.3333, 1)^(−0.544) = 1.3333^(−0.544) = 0.8390
Cystatin C component:
- Scys/0.8 = 1.19/0.8 = 1.4875
- 1.4875 > 1, so:
- min(1.4875, 1)^(−0.323) = 1.0^(−0.323) = 1.0
- max(1.4875, 1)^(−0.778) = 1.4875^(−0.778) = 0.7310
Age factor:
- 0.9961^27 = 0.8983
eGFR = 135 × 1.0 × 0.8390 × 1.0 × 0.7310 × 0.8983
= 135 × 0.8390 × 0.7310 × 0.8983 = ~74.3 mL/min/1.73m²
2. CKD-EPI Creatinine Only (2021)
eGFR = 142 × min(1.2/0.9, 1)^(−0.302) × max(1.2/0.9, 1)^(−1.200) × 0.9938^27 = 142 × 1.0 × 1.3333^(−1.200) × 0.8451 = 142 × 1.0 × 0.7386 × 0.8451 = ~88.7 mL/min/1.73m²
3. CKD-EPI Cystatin C Only (2012)
eGFR = 133 × 1.0 × 1.4875^(−1.328) × 0.996^27 = 133 × 0.5825 × 0.8984 = ~69.6 mL/min/1.73m²
4. Cockcroft-Gault CrCl
CrCl = [(140 − 27) × 85] / [72 × 1.2] = [113 × 85] / 86.4 = 9605 / 86.4 = ~111.2 mL/min
Summary Table
| Equation | eGFR / CrCl | Use |
|---|---|---|
| CKD-EPI Creatinine only (2021) | ~88.7 mL/min/1.73m² | Screening |
| CKD-EPI CysC only (2012) | ~69.6 mL/min/1.73m² | When Cr unreliable |
| CKD-EPI Cr + CysC (2021) | ~74.3 mL/min/1.73m² | Best GFR estimate |
| Cockcroft-Gault | ~111 mL/min | Drug dosing only |
Interpretation
| Best eGFR estimate | ~74 mL/min/1.73m² |
| CKD Stage | G2 - Mildly decreased (60-89) |
Compared to previous result (SCr 0.9 → eGFR ~89):
| SCr | Combined eGFR | Stage |
|---|---|---|
| 0.9 mg/dL | ~88.7 mL/min/1.73m² | G2 high |
| 1.2 mg/dL | ~74.3 mL/min/1.73m² | G2 mid |
- Raising SCr from 0.9 → 1.2 drops the combined eGFR by ~14 units - a meaningful difference
- Both creatinine (1.2) and cystatin C (1.19) are now concordantly elevated - this strengthens confidence that eGFR ~74 reflects true kidney function, not just a CysC artefact from inflammation
- At 85 kg/27 years, creatinine 1.2 is at the upper limit of normal for a muscular male - this may still slightly overestimate dysfunction, but the concordance with CysC makes the ~74 estimate reliable
- CG of ~111 mL/min is inflated by weight and should not be used for CKD staging
Clinical priority:
- UACR is now more important than ever - with eGFR 74 + both markers elevated, confirming or ruling out albuminuria determines whether this is true CKD G2
- Repeat in 3 months to establish chronicity
- hsCRP 4.0 still noted - if inflammation resolves and CysC normalises, eGFR may improve closer to the creatinine-only estimate of ~89
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