Advanced Serum Creatinine Calculator

Calculated Results

Results appear above the form after submission.

Calculator Inputs

Sex

Age (years)

Weight (kg)

Height (cm)

Serum Creatinine

Serum Creatinine Unit

BUN (mg/dL, optional)

Urine Volume (mL, optional)

Urine Creatinine (optional)

Urine Creatinine Unit

Collection Duration (hours, optional)

Example Data Table

Case	Sex	Age	Weight (kg)	Height (cm)	Serum Cr	BUN	Estimated eGFR	Estimated CrCl
Example A	Male	46	78	176	1.00 mg/dL	16 mg/dL	~95 mL/min/1.73m²	~102 mL/min
Example B	Female	64	63	160	1.30 mg/dL	26 mg/dL	~46 mL/min/1.73m²	~45 mL/min
Example C	Male	71	70	168	132 µmol/L	22 mg/dL	~53 mL/min/1.73m²	~58 mL/min

Formula Used

1) Unit Conversion

mg/dL = µmol/L ÷ 88.4

µmol/L = mg/dL × 88.4

2) eGFR by CKD-EPI 2021

eGFR = 142 × min(SCr/k,1)^a × max(SCr/k,1)^-1.200 × 0.9938^Age × sex factor

k = 0.7 for female, 0.9 for male
a = -0.241 for female, -0.302 for male
Sex factor = 1.012 for female, 1.000 for male

3) Cockcroft-Gault Creatinine Clearance

CrCl = ((140 − age) × weight × sex factor) ÷ (72 × SCr)

Sex factor is 0.85 for female and 1.00 for male.

4) Body Surface Area and Adjustment

BSA = √((height × weight) ÷ 3600)

Adjusted CrCl = CrCl × (1.73 ÷ BSA)

5) Measured Urinary Creatinine Clearance

Measured CrCl = (Urine Cr × Urine Flow Rate) ÷ Serum Cr

Urine flow rate is total urine volume divided by collection minutes.

6) BUN/Creatinine Ratio

BUN/Cr Ratio = BUN ÷ Serum Creatinine

How to Use This Calculator

Step 1: Choose sex, then enter age, weight, and height.

Step 2: Enter serum creatinine and select the correct unit.

Step 3: Add BUN if you want the BUN/creatinine ratio.

Step 4: Enter timed urine details only when measured clearance is available.

Step 5: Press the calculate button to show results above the form.

Step 6: Review the graph, then export the results as CSV or PDF.

Frequently Asked Questions

1) What does serum creatinine measure?

Serum creatinine reflects a waste product in blood produced by muscles and cleared by kidneys. Higher values can suggest reduced kidney filtration, but hydration, muscle mass, and medications also influence results.

2) Why does the calculator show eGFR and creatinine clearance?

They estimate kidney function in different ways. eGFR is commonly reported by laboratories, while Cockcroft-Gault clearance is often used for medication dosing and renal adjustment decisions.

3) Which serum creatinine unit should I use?

Use the exact unit reported by your lab. Many reports use mg/dL, while others use µmol/L. The calculator converts automatically and keeps all formulas internally consistent.

4) Can low muscle mass affect serum creatinine?

Yes. Lower muscle mass may reduce creatinine even when kidney function is impaired. That is why serum creatinine must be interpreted alongside age, body size, symptoms, and trend data.

5) When should I enter BUN values?

Enter BUN when you want additional context about dehydration, prerenal states, or broader renal assessment. The ratio alone does not diagnose the cause of kidney injury.

6) What is measured urinary creatinine clearance?

It uses timed urine creatinine concentration, urine volume, and serum creatinine to estimate actual clearance. It can help when a direct collection study is available.

7) Is a single high result always dangerous?

Not always. A single abnormal value needs clinical context. Recent exercise, dehydration, dietary intake, and some drugs may shift creatinine temporarily. Repeated testing often matters more.

8) Can this calculator replace medical advice?

No. This tool supports estimation and review. Diagnosis, staging, medication dosing, and urgent decisions should be confirmed by a qualified clinician using complete clinical information.