The kidney is a late responding tissue of significant importance as:
- It is commonly irradiated in abdominal treatments
- It is a classical example of an organ whose radiation tolerance decreases with passing time
There are several endpoints for late kidney toxicity:
- Renal failure
- Hypertension
Clinical Features
Mild renal failure and hypertension may be asymptomatic. Symptoms of more advanced renal failure can include fatigue and symptoms of hypercalcaemia. Oligouria is usually a late sign.
On examination, blood pressure may be elevated. There may be no overt signs of renal failure.
Laboratory tests typically show an elevated creatinine from baseline, but this may appear normal even if there is significant loss of glomeruli.
Pathophysiology
Microscopically, there is loss of glomeruli and replacement with fibrotic tissue, most likely due to death of endothelial cells. The tubules of the kidney are not affected unless higher doses are given.
Tolerance Dose
The TD5/5 for the entire kidney is 18 Gy; the TD50/5 is 28 Gy. There is a significant volume effect (V28 Gy < 20% gives under 5% risk of toxicity); however if the mean dose to one kidney is over 20 Gy it is recommended that the mean dose for the other be below 6 Gy to prevent symptomatic late effects.
Scoring Systems
The RTOG scale for kidney effects:
| Grade | 0 | ~1 | 2 | 3 | 4 | 5 |
|---|---|---|---|---|---|---|
| Findings | Normal | Mild renal impairment, mild hypertension | Moderate renal impairment, moderate hypertension, no anaemia | Severe findings, persistent anaemia | Malignant hypertension, renal failure requiring dialysis | Death |
Links
Back to Late Effects in Normal Tissues
Back to contents
