RenalPlasmaClearanceEstimator

Utility description: Renal Plasma Clearance Estimator

Renal Plasma Clearance Estimator — Estimation of Renal Plasma Clearance (GFR and ERPF)

ℹ️  Utility calculates Glomerular Filtration Rate (GFR) or Effective Renal Plasma Flow (ERPF):
    • Based on single-sample blood analysis method
    • Considering injected activity and plasma concentration
    • With normalization to Body Surface Area (BSA)

⚠️  CRITICAL: Accuracy depends on sampling time!
    DTPA: sample at 120 min. MAG3: sample at 40-50 min.
    Error in determining net injected activity leads to proportional error in result.

Usage:
  RenalPlasmaClearanceEstimator.exe                            → demo mode (console output)
  RenalPlasmaClearanceEstimator.exe input.csv output.json      → evaluate your data

Input format:
PatientID,StudyDate,InjectedActivityMBq,PreInjectionSampleCounts,PostInjectionSampleCounts,BloodSampleCountsPerML,TimePostInjectionMin,PatientWeightKg,PatientHeightCm,PatientAge,Gender,Radiopharmaceutical

Example:
  PAT-GFR-001,2026-07-21,100.0,500000,5000,2500,120,70,175,45,M,DTPA

— WHY IS THIS NEEDED?
Quantitative assessment of kidney function is the gold standard in nephrology.
• Tc-99m DTPA is filtered by glomeruli, so its clearance equals GFR.
• Tc-99m MAG3 is secreted by tubules, so its clearance equals ERPF.
• Single-sample method (taking one blood sample at a specific time) is less accurate than multi-sample, but much more convenient for patient and clinic.
• Results are normalized to standard body surface area (1.73 m²) for comparison between patients.

⚠️  CRITICAL:
• Net injected activity = (Pre-counts - Post-counts) / Pre-counts * Syringe Activity. Any drug loss must be accounted for.
• Sampling time is critical: for DTPA distribution phase ends by 120 min, for MAG3 — by 40-50 min.
• Plasma volume is estimated indirectly through patient weight and height.
• Hematocrit affects plasma volume; if patient's exact hematocrit is known, calculation can be refined.

Key features:
• Automatic calculation of net injected dose by syringe counts.
• Selection of calculation model depending on drug (DTPA or MAG3).
• Normalization of results to Body Surface Area (Du Bois formula).
• Check of sampling time optimality.
• Interpretation of results relative to age norms.

Critical parameters:
• GFR normal: 90–120 mL/min/1.73m²
• ERPF normal: 400–600 mL/min/1.73m²
• DTPA sampling time: 110–130 min
• MAG3 sampling time: 40–50 min

💡 Usage tips:
1. Carefully measure syringe activity before and after injection in the same geometry (counter).
2. Blood sample must be taken exactly at the specified time. Deviation of more than 5 minutes requires coefficient adjustment.
3. For obese or edematous patients, plasma volume estimation by weight may be inaccurate.
4. If clearance is below normal, it is recommended to repeat the study using multi-sample method to construct full clearance curve.
5. Consider medications affecting renal blood flow (e.g., NSAIDs) before the study.

⚠️ Note: This utility links the pharmaceutical part (drug activity) with clinical physiology. It allows objectification of kidney function, which is impossible to do only by visual inspection of the scintigram. Results are used for staging Chronic Kidney Disease (CKD) and making decisions about dialysis or transplantation.