- For each exchange type, enter the fill volume (L), choose the dextrose concentration (1.5 / 2.5 / 4.25%), and enter the number of bags per day. Up to four rows are provided — leave unused rows at 0.
- For APD (cycler), just sum the total fill volume for each concentration into the volume field (e.g. 10 L of 2.5% as volume 10, bags 1) — the math is identical.
- Set the glucose absorption fraction. The default 60% reflects a typical CAPD/APD dwell; raise it for long dwells, higher tonicity, or high transporters, lower it for short rapid cycles.
- Read the daily glucose absorbed (g), caloric load (kcal), and total instilled glucose (g), plus an interpretation of the metabolic burden.
All computation runs in your browser; no values are stored or transmitted.
When to Use
Use this estimator for any peritoneal dialysis patient — CAPD or APD — to quantify the daily glucose and calories absorbed from the dialysate itself. Dextrose is the osmotic agent in standard PD fluid, and a substantial fraction crosses the peritoneum during every dwell. That continuous, obligatory glucose load drives weight gain, worsens glycemic control in diabetics, contributes to dyslipidemia, and can blunt appetite. Putting a number on it makes the problem visible and gives you a target to act on.
Appropriate use
Counselling PD patients with new or worsening weight gain, hyperglycemia, or hypertriglyceridemia; comparing prescriptions before and after switching the long dwell to icodextrin; estimating the dietary "calorie credit" that the dialysate already supplies when planning energy intake; and educating patients on why their PD prescription matters metabolically.
What it is NOT
This is a population-level estimate, not a measured value. The true absorbed fraction varies widely between patients (roughly 40–80%) and depends on peritoneal transport status, dwell time, tonicity, and residual function — it can only be confirmed with a peritoneal equilibration test (PET) and effluent measurement. Icodextrin (the glucose-polymer long-dwell fluid) and amino-acid solutions are NOT dextrose and should be entered as 0 g/L equivalents (omit those exchanges). Do not use the kcal figure as the sole basis for a prescription change.
Pearls & Pitfalls
Read the bag label as monohydrate
PD bag percentages are dextrose monohydrate: 1.5% = 15 g/L, 2.5% = 25 g/L, 4.25% = 42.5 g/L. (Anhydrous glucose is ~9.1% lower: ≈13.6, 22.7, and 38.6 g/L respectively.) This tool computes instilled glucose from the labelled monohydrate grams per litre and applies 3.4 kcal/g of absorbed dextrose monohydrate — the transparent, standard convention. Higher tonicity means a much larger glucose payload, so the 4.25% long dwell is usually the dominant contributor.
Spare glucose on the long dwell
The long dwell (overnight in CAPD, the day dwell in APD) absorbs the most glucose because it lasts the longest. Replacing it with icodextrin removes that dextrose load while maintaining ultrafiltration, and is the single highest-yield glucose-sparing move. Recompute here with the long dwell omitted to show the patient the calorie reduction.
Pitfalls
(1) The absorbed fraction is patient-specific — 60% is only a default; high transporters absorb more. (2) Do not enter icodextrin or amino-acid exchanges as dextrose. (3) The kcal figure is gross energy from dialysate glucose, not a prescription order. (4) In diabetics the absorbed glucose raises insulin requirements — counsel and monitor; do not assume the dialysate is "free." (5) Confirm against the actual bag labels and the dwell schedule rather than assumptions.
Why Use It
Dialysate glucose is an invisible, continuous calorie infusion. A typical CAPD prescription can deliver several hundred kilocalories a day from absorbed dextrose alone — enough to explain unexplained weight gain, sabotage glycemic targets, and feed hypertriglyceridemia. Because patients and clinicians rarely "see" these calories, the metabolic consequences of PD are often missed. Quantifying the load reframes the conversation: it justifies dietary adjustment, supports the case for icodextrin or lower-tonicity prescriptions, and sets a measurable target for reducing glucose exposure in line with ISPD guidance to minimize glucose where clinically possible.
PD Glucose Absorption & Caloric Load Estimator
Enter each PD exchange type — fill volume, dextrose concentration, and bags per day — then set the absorption fraction to estimate the daily glucose absorbed (g) and caloric load (kcal). Leave unused rows at 0; blank fields are treated as 0.
⚕ Instilled glucose (g/day) = Σ [volume(L) × g/L × bags], where g/L is the labelled dextrose monohydrate (1.5%=15, 2.5%=25, 4.25%=42.5 g/L). Absorbed glucose = instilled × absorption fraction (default 60%). Caloric load = absorbed g × 3.4 kcal/g (dextrose monohydrate). This is a population estimate, not a measured value — true absorption varies ~40–80% by transport status and dwell. Source: Grodstein GP et al. Kidney Int. 1981;19(4):564–567; Burkart JM. Semin Dial. 2004;17(6):498–504.
Next Steps
Use the result to guide the metabolic side of the PD prescription.
- Counsel the patient on diet: the absorbed dialysate calories should be counted in total energy intake, not added on top of a full oral intake.
- In diabetics, anticipate higher insulin/medication requirements and intensify glycemic monitoring; the load is continuous, not bolused.
- If the load is high, consider switching the long dwell to icodextrin and/or using the lowest tonicity that achieves adequate ultrafiltration; recompute here to show the reduction.
- Watch for weight gain and hypertriglyceridemia; review lipids and trend dry weight.
- Confirm transport status (PET) before assuming a fixed absorption fraction, and refer to your dialysis team / nephrologist for prescription changes.
Evidence & References
Formula & Conventions
| Quantity | Equation / value |
|---|---|
| Glucose per litre (monohydrate) | 1.5% = 15 g/L · 2.5% = 25 g/L · 4.25% = 42.5 g/L |
| Anhydrous glucose (reference) | ≈13.6 · 22.7 · 38.6 g/L (monohydrate × 0.909) |
| Total instilled glucose (g/day) | Σ over exchanges [ volume (L) × g/L × bags/day ] |
| Glucose absorbed (g/day) | total instilled × absorption fraction (default 0.60) |
| Caloric load (kcal/day) | absorbed g × 3.4 kcal/g (dextrose monohydrate) |
Caloric-load interpretation bands
| kcal/day from PD glucose | Interpretation |
|---|---|
| < 200 | Modest load — routine dietary awareness |
| 200–400 | Meaningful load — count calories, monitor weight & glucose |
| > 400 | Clinically significant — consider icodextrin / lower tonicity, tighten glycemic and lipid monitoring |
Bands are pragmatic thresholds for counselling, not validated cut-points. A >400 kcal/day dialysate glucose load is widely regarded as a clinically important driver of weight gain, hyperglycemia, and dyslipidemia in PD.
Evidence & References
Glucose absorption across a PD dwell averages roughly 60% (range ~40–80%) and rises with dwell length, dialysate tonicity, and high peritoneal transport status (Grodstein et al.). The metabolic consequences — weight gain, insulin resistance, and dyslipidemia — are well described (Burkart). Icodextrin, a glucose polymer, spares dextrose on the long dwell while sustaining ultrafiltration (Davies et al.), and ISPD guidance recommends minimizing glucose exposure where clinically feasible.
- Grodstein GP, Blumenkrantz MJ, Kopple JD, et al. Glucose absorption during continuous ambulatory peritoneal dialysis. Kidney Int. 1981;19(4):564–567.
- Burkart JM. Metabolic consequences of peritoneal dialysis. Semin Dial. 2004;17(6):498–504.
- Davies SJ, Woodrow G, Donovan K, et al. Icodextrin improves the fluid status of peritoneal dialysis patients: results of a double-blind randomized controlled trial. J Am Soc Nephrol. 2003;14(9):2338–2344.
- Brown EA, Blake PG, Boudville N, et al. International Society for Peritoneal Dialysis practice recommendations: prescribing high-quality goal-directed peritoneal dialysis. Perit Dial Int. 2020;40(3):244–253.
