Radiation Nephropathy Treatment & Management

As with chronic renal disease of any kind, the major risk with radiation nephropathy and BMT nephropathy is progressive loss of renal function with evolution to end-stage renal failure. Concomitant hypertension predisposes patients to stroke and heart disease. Uncontrolled hypertension may accelerate the loss of renal function. To slow the progression of renal disease, good control of blood pressure must be maintained; this is also true for radiation nephropathy and BMT nephropathy. (Monitoring blood pressure for 24 hours [ambulatory blood pressure monitoring] may help to differentiate true hypertension from white-coat hypertension.)

Antihypertensive agents are an important part of clinical management of radiation nephropathy or BMT nephropathy. The goal of therapy is to keep blood pressure at less than 130/85 mm Hg or 125/75 mm Hg if the patient has proteinuria of greater than 1000 mg/d.

Other drugs used in renal disease treatment include the following:

• Diuretics - Treat fluid overload and enhance potassium excretion
• Sodium polystyrene sulfonate- Treats hyperkalemia
• Fludrocortisone - Treats aldosterone deficiency and hyperkalemia

Patients with radiation nephropathy or BMT nephropathy may be more anemic than expected for their level of renal function. Anemia may be treated with subcutaneous injections of erythropoietin.

Dietary salt restriction probably helps to control hypertension in cases of radiation nephropathy or BMT nephropathy. Patients must avoid instant, processed, or snack foods, and they must not use salt in cooking or at the dining table. No specific activity restrictions are necessary.

No specific consultations are necessary other than those that may arise from intercurrent illness. A patient who has undergone BMT may have other medical problems, such as hypothyroidism, cataracts, or bone avascular necrosis. Secondary cancers are a substantial risk, so ongoing oncologic follow-up is essential. Patient transfer or referral may be necessary in the event of complications or management difficulty.

ACE inhibitors, ARBs, and/or calcium channel blockers control blood pressure. Improved blood pressure control helps to slow the progression of renal failure. In patients with chronic kidney disease, especially when the serum creatinine level is elevated or the GFR is reduced, more than 1 antihypertensive drug is typically needed to control blood pressure.

No proof suggests that one type of antihypertensive agent is superior to another in radiation nephropathy and BMT nephropathy. Nonetheless, ACE inhibitors are favored because of their known benefit in other progressive kidney diseases.^[14] An angiotensin II blocker (ARB) was shown to be very effective in a single case of radiation nephropathy.^[15] There are no randomized trials of ACE inhibitors or ARBs in human radiation nephropathy. ACE inhibitors or ARBs may be the best medicines to use, but definitive proof is lacking.

In experimental studies of radiation nephropathy, ACE inhibitors and ARBs have been particularly effective in the treatment and prevention of histologic injury and renal function loss.^[16] Conversely, angiotensin II infusion in experimental radiation nephropathy models has had distinct adverse effects. The use of ACE inhibitors (eg, captopril) may mitigate, or even entirely prevent, radiation nephropathy if patients are started soon enough after the initial irradiation.^[17] This effect has been demonstrated in experimental animals.

In a clinical study of the use of captopril versus a placebo in patients who underwent radiation-based hematopoietic stem cell transplantation, a lower serum creatinine level and a higher GFR were found after 1 year in the captopril patients, in comparison with the placebo patients.^[17]

In-hospital care may be needed for complications, such as fluid overload or hyperkalemia. With any patient with chronic renal disease, intercurrent illness may precipitate hospitalization.

In the case of acute BMT nephropathy associated with an HUS- and/or a TTP-like disorder, the use of plasma exchange may be considered. This treatment may reverse the hematologic component, but it does not improve renal function.^[18] Most patients with renal insufficiency require a dose adjustment for many medications. One should avoid the use of any nephrotoxic medications, such as nonsteroidal anti-inflammatory drugs (NSAIDs). Should it become necessary to use intravenous (IV) radiocontrast, the use of IV isotonic sodium chloride solution should reduce the risk of contrast nephrotoxicity.

Outpatient care of any patient with chronic renal failure requires sufficient frequency of doctor visits, attention to blood pressure control, and assessment of the rate at which renal function is lost. These principles are valid for radiation nephropathy and BMT nephropathy. Monthly or weekly outpatient visits may be needed for patients whose blood pressure remains uncontrolled or who have fluid overload requiring an adjustment of diuretic doses.

The rate of loss of kidney function is adequately assessed by construction of a graph of 100/plasma creatinine versus time. Such a graph should be updated after each visit. Such a graph may permit prediction of future decline in renal function and its timing. (See Rate of Kidney Function Loss.)

Follow-up of patients who have received therapeutic irradiation must address not only the cancer for which they were irradiated but also the possible injury to healthy tissue. For this reason, patients who have undergone BMT must have periodic medical visits.

In addition, the use of new therapies involving radiation, such as radioisotope therapies, requires careful monitoring for unexpected injuries to healthy tissue. These injuries have occurred with the use of ⁹⁰ Y-tagged somatostatin and ¹⁶⁶ Ho-tagged phosphonate.^{[5, 6]}

Any patient with chronic renal disease must comply with outpatient follow-up and blood pressure control. This compliance helps to slow the decline in renal function; the same is true for patients with radiation nephropathy or BMT nephropathy.

Patients must be aware of their maintenance medications and dosages. They must avoid nephrotoxins, such as over-the-counter nonsteroidal arthritis medicines, including ibuprofen.