multifactorial and may relate to chemotherapy, transfusion, or subclinical liver injury Unexpected moderate or severe hyperbilirubinemia should be fully assessed Diarrhea in an oncology patient may be triggered by a variety of causes including radiation injury, chemotherapy, and C difficile colitis due to prolonged hospitalizations and/or use of broad-spectrum antibiotics Venoocclusive disease (VOD) of the liver is a rare but important complication to recognize Risk factors include exposure to actinomycin-D chemotherapy and liver radiation Manifestations include hepatomegaly, transaminitis, thrombocytopenia, and ascites The thrombocytopenia is frequently more than what would be expected from the chemotherapy alone or may occur at the wrong timing relative to chemotherapy Once the diagnosis is suspected, a hepatic ultrasound with Doppler assessment of hepatic vein flow should be performed Reversal of flow in the small hepatic veins establishes the diagnosis in the appropriate clinical setting Management is supportive until the problem resolves on its own Most patients will require admission for both observation and support For a discussion of typhlitis, see section on “Infectious Complications of Cancer Treatment.” RENAL COMPLICATIONS OF CANCER THERAPY Renal injury from cancer treatment is very common and some degree of renal dysfunction is frequently present even in patients with normal creatinine for age Other patients will have documented renal dysfunction based on elevated creatinine, decreased glomerular filtration rate (GFR), or decreased 24-hour creatinine clearance Renal complications may also lead to metabolic disturbances (see “Metabolic Complications of Cancer Treatment” section) Uric-acid nephropathy can occur in patients with very high cell turnover (see “Leukemia” section) Drug-induced renal injury is common in oncology patients ( Table 98.8 ) Radiation injury to the kidney may cause renal insufficiency as well as radiation nephritis, to months after treatment Typical findings include the manifestations of vasculitis with hemolytic uremic syndrome (HUS) Oncology patients are also at risk for medical renal disease associated with poor perfusion, exposure to multiple nephrotoxic agents, and hypertension Since renal injury is common, it is appropriate to check BUN, creatinine, electrolytes, calcium, magnesium, and phosphate in all ill oncology patients If significant abnormalities are noted, the oncology-specific history should be reviewed to determine specific risk factors or exposures that may help explain the problem In general, the management of significant abnormalities is not unique in patients with cancer and should follow the guidelines in Chapter 100 Renal and Electrolyte Emergencies Consider the possibility of a decreased GFR (whether