The Kidney Simulator
A living model of the heart and kidneys. Move a dial and watch blood split at the filter in real time — filtrate one way, blood the other, urine into the beaker. Nothing here is your data; it is a teaching model you can push around freely.
Loading the kidney simulator…
Best on a laptop or tablet. On a phone, tap Controls to open the dials.
Start with a scenario
You do not have to know which dial matters. Click a scenario and every dial travels to that clinical state in front of you — dehydration, blood loss, septic shock, uncontrolled blood pressure, early diabetic kidney disease — each one with a sentence telling you where to look. Under them is a ladder of the five CKD stages: click down it and watch the marker walk across the KDIGO grid the way a chart does over years.
The drug cabinet
Along the bottom of the simulation is a row of pills. Drop one on the kidney and watch what it does: an ACE inhibitor relaxes the vessel leaving the filter, so filtration eases and creatinine ticks up a little — the expected bump that is why labs get rechecked two weeks after you start one. An NSAID clamps the vessel going in and takes away the kidney’s own defence with it. A loop diuretic quadruples urine output. An SGLT2 inhibitor produces the small deliberate dip that means it is working.
They stack, which is the interesting part. Put an NSAID on top of an ACE inhibitor on top of a dehydrated patient and you get the combination clinicians warn each other about, with the numbers to show why.
What you can change
Every slider is a real physiological lever. The point is not to hit a target number — it is to see which numbers move together, and which move apart.
- Heart rate & blood pressure
- The push behind everything downstream. Raise the pressure and watch renal blood flow climb with it.
- Hydration
- How much water the body is holding. Sets how much filtrate gets reabsorbed versus passed as urine.
- Afferent & efferent arterioles
- The vessels into and out of the filter. Squeezing them in opposite directions moves filtration in opposite directions — this is what most blood pressure medications act on.
- Kidney health
- The fraction of nephrons still working. Drag it down and you get the chronic kidney disease story: falling GFR, rising creatinine.
- Filter barrier
- How well each filter seals, separately from how many you have. Damage it and albumin escapes into the urine — your ACR climbs while your eGFR sits still. This is the second axis of kidney disease, and the one that moves first.
- Autoregulation
- The kidney's own defence, holding GFR steady between roughly 80 and 180 mmHg. Switch it off and the plateau collapses.
What the numbers mean
The strip under the simulation and the traces beside it are the same measurements your nephrologist reads on a lab report — just updating live instead of once every few months.
- GFR
- How much plasma the filters clear each minute.
- eGFR
- The same number in the form your lab report uses to stage CKD.
- Creatinine
- The waste product that builds up when filtration falls behind.
- Filtration fraction
- The share of arriving plasma that actually gets filtered.
- Urine output
- What finally leaves the body — collected in the beaker on screen.
- ACR
- Albumin-to-creatinine ratio: how much protein is leaking through. It is the other half of KDIGO staging, and it usually moves years before eGFR does.
This simulator is a simplified teaching model, not a diagnostic tool. It cannot tell you anything about your own kidney function. For that, see how to read your kidney lab results and talk to your care team.
Related reading
These guides cover the next questions patients usually have after this topic.