What labs to order for a patient with new normocytic anemia on Eliquis (apixaban) with no obvious signs of bleeding?

From the Guidelines

For a patient with new normocytic anemia on Eliquis (apixaban) with no obvious signs of bleeding, I recommend ordering a complete blood count (CBC) with differential, reticulocyte count, comprehensive metabolic panel (CMP), iron studies (including ferritin, iron, TIBC, and transferrin saturation), vitamin B12, folate levels, and coagulation studies (PT/INR, aPTT). Additionally, order a fecal occult blood test to check for occult GI bleeding, which is a concern in patients on anticoagulants like apixaban 1. Consider hemolysis workup with LDH, haptoglobin, and peripheral blood smear. These tests will help determine if the anemia is due to occult bleeding from anticoagulation, bone marrow suppression, nutritional deficiencies, or other causes. The reticulocyte count is particularly important as it differentiates between decreased production versus increased destruction or loss of red blood cells, as suggested by the guidelines for evaluating anemia 1. In patients on Eliquis, occult bleeding is a primary concern even without obvious clinical signs, as anticoagulants increase bleeding risk throughout the gastrointestinal tract and elsewhere. If significant anemia is found, temporary dose adjustment or interruption of apixaban might be necessary depending on the severity and cause of anemia. It's also important to confirm iron deficiency by iron studies prior to investigation, as recommended by the British Society of Gastroenterology guidelines for the management of iron deficiency anaemia in adults 1. A comprehensive metabolic panel and complete blood count with differential are also recommended for monitoring patients with systemic diseases, as suggested by the European League Against Rheumatism recommendations 1 and consensus recommendations for the diagnosis and clinical management of Rosai-Dorfman-Destombes disease 1.

Some key points to consider when evaluating normocytic anemia include:

• The morphologic approach to evaluating anemia, which characterizes anemia based on the mean corpuscular volume (MCV) 1
• The kinetic approach, which focuses on the underlying mechanism of anemia, distinguishing among the production, destruction, and loss of RBCs 1
• The importance of iron studies, including ferritin, iron, TIBC, and transferrin saturation, in diagnosing iron deficiency anemia 1
• The need to consider hemolysis workup with LDH, haptoglobin, and peripheral blood smear in patients with normocytic anemia 1
• The potential for occult bleeding in patients on anticoagulants like apixaban, even without obvious clinical signs 1.

From the Research

Laboratory Evaluation of Normocytic Anemia

To evaluate a patient with new normocytic anemia on Eliquis (apixaban) with no obvious signs of bleeding, the following laboratory tests can be considered:

• Complete blood count (CBC) to confirm the anemia and determine the mean corpuscular volume (MCV) 2
• Reticulocyte count to differentiate between hypoproliferative and hyperproliferative anemias 2, 3
• Peripheral blood smear to examine the morphology of red blood cells 2, 4
• Red blood cell distribution width (RDW) to assess the variability in red blood cell size 3
• Serum iron level, total iron-binding capacity, and serum ferritin level to evaluate for iron deficiency anemia, although these may not be directly relevant in normocytic anemia 2
• Lactate dehydrogenase (LDH), unconjugated bilirubin, and haptoglobin levels to assess for hemolysis 4
• Direct antiglobulin test (DAT) to differentiate between immune and non-immune causes of hemolysis 4

Specific Considerations for Eliquis (Apixaban)

Given the patient's use of Eliquis (apixaban), an anticoagulant, it is essential to consider the possibility of bleeding, even if not overtly apparent. However, the primary focus in the context of normocytic anemia would still be on identifying the underlying cause of the anemia rather than the anticoagulant itself.

Approach to Normocytic Anemia

The approach to normocytic anemia involves a thorough history and physical examination, followed by basic diagnostic studies as mentioned above. Further testing is guided by the results of these initial studies 3. In some cases, particularly if the anemia is unexplained after initial evaluations, bone marrow examination may be considered, although it is rarely contributive in the setting of normocytic-normochromic anemia of unknown cause 5.