Radiation Nephropathy Clinical Presentation

Updated: Dec 01, 2015
  • Author: Eric P Cohen, MD; Chief Editor: Vecihi Batuman, MD, FASN  more...
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Presentation

History

Previous exposure to a sufficient dose of ionizing radiation is a necessary element in the patient's history. External-beam irradiation is usually a clear-cut feature in the history, and it should have encompassed the kidney areas. Use of a radioactive isotope in therapeutic doses may not be obvious. Classically, exposure of the kidneys to x-rays or gamma rays in a dose higher than 2000 cGy (rads) is required to cause radiation nephropathy. However, a 10-Gy single-fraction dose is sufficient to cause chronic renal failure after BMT, [11] and with many years of follow-up, a 1-Gy single-fraction dose is associated with development of chronic kidney disease. [4] While these effects are not immediate, as is the case for radiation injury to the bone marrow or GI tract, kidney injury at these doses indicates that the kidneys are quite radiosensitive.

Modern radiation therapy is sharply focused on the area to be treated; therefore, it is very unlikely that the kidneys would be irradiated in a case of irradiation for uterine cervical cancer or for prostate cancer.

In patients who have undergone BMT, a history of total-body irradiation for pre-BMT conditioning should be determined. Partial renal shielding reduces, but does not eliminate, the risk of BMT nephropathy.

Because radiation nephropathy is a delayed injury, renal disease that quickly follows kidney irradiation (ie, within hours or days) is usually caused by some other factor. Classic acute radiation nephropathy occurs 6-12 months after irradiation, and chronic radiation nephropathy may not develop for years. Similarly, proteinuria or hypertension ascribed to radiation nephropathy does not develop for months or years.

Expected symptoms of radiation nephropathy and BMT nephropathy are the same as those observed in patients with chronic renal disease. Nocturia may develop due to the loss of urine concentrating ability. Retention of salt and water may lead to edema and an increase in blood pressure. Anemia may occur, with fatigue, dyspnea, and loss of endurance. Loss of appetite, nausea, and weight loss may occur when there is a severe reduction in renal function. Itching may occur with advanced renal failure, that is, stage V chronic kidney disease (see Staging).

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Physical Examination

Hypertension, often severe, is a major feature of radiation nephropathy. It may be the only clinical feature. When this blood pressure elevation is associated with end-organ damage, such as eyeground changes or encephalopathy, it is termed malignant. Malignant hypertension has been reported in radiation nephropathy. Eyeground abnormalities, such as cotton-wool spots, retinal hemorrhage, and even optic disc edema, may occur at levels of blood pressure elevation that ordinarily would not cause such eyeground changes. [12]

Long-standing hypertension may result in left ventricular enlargement or hypertrophy, which may be detectable on examination. Findings on physical examination are not specific for radiation nephropathy or BMT nephropathy.

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