This crossover safety study will evaluate the safety of a single dose of ferumoxytol compared to placebo in patients with chronic kidney disease.

This is a double-blind, placebo controlled, crossover design study of the safety of ferumoxytol compared to placebo. Patients are randomized to receive either one 510 mg dose of ferumoxytol or the equivalent volume of normal saline followed by the other test article given one week later.

Inclusion Criteria:

• Male or female patients > 18 years.
• Have chronic kidney disease per K/DOQI guidelines.
• Baseline hemoglobin of > 9.0 and < 12.5 g/dl

Exclusion Criteria:

• Women who are pregnant or lactating.
• Received another investigational drug or device within 30 days.
• Recent parenteral or oral iron therapy.
• Patients that have other causes of anemia.
• Major surgery within 30 days or anticipated or planned surgery during the study.
• Patients with active infections.
• Recent blood transfusions.
• Patients with known allergies to iron products.