From the Guidelines
I strongly recommend against proceeding with a CT angiogram as the initial step to investigate the cause of the patient's declining hemoglobin, and instead suggest a systematic approach to identify the underlying cause. The differential diagnosis for anemia in this 61-year-old diabetic patient with osteomyelitis includes medication-related blood loss (clarithromycin can cause GI irritation), occult GI bleeding, anemia of chronic disease/inflammation from osteomyelitis, bone marrow suppression from antibiotics, nutritional deficiencies, and diabetic nephropathy with reduced erythropoietin production 1. Initial investigations should include:
- Complete blood count with reticulocyte count
- Iron studies (ferritin, transferrin saturation)
- Vitamin B12 and folate levels
- Peripheral blood smear
- Fecal occult blood testing If these are inconclusive and hemoglobin continues to drop despite transfusion, then endoscopic evaluation would be more appropriate than CT angiogram as the first step to evaluate for GI bleeding, since the patient has no signs of acute hemorrhage 1. CT angiogram would be indicated only if there are signs of active bleeding with hemodynamic instability or if endoscopic studies fail to identify a source of significant blood loss. The transfusion to maintain hemoglobin above 80 g/L was appropriate, especially in a diabetic patient where adequate oxygen-carrying capacity is important for wound healing in osteomyelitis. It is essential to consider the patient's overall clinical picture, including the presence of osteomyelitis and diabetes, when determining the best course of action to investigate and manage the declining hemoglobin 1.
From the Research
Differential Diagnosis for Reducing Hemoglobin
The patient's reducing hemoglobin level, despite the absence of visible bleeding, can be attributed to various factors. Some possible differentials include:
- Gastrointestinal bleeding, although the patient denied any malena or bleeding in stool 2
- Sepsis or shock, which can cause a drop in hematocrit 2
- Volume shifts or post-procedure bleeding 2
- Iron deficiency anemia, which is a common cause of low hemoglobin levels 3, 4
- Hemolysis or blood loss, which can be evaluated using reticulocyte count 5
Investigations for Reducing Hemoglobin
To investigate the cause of the reducing hemoglobin level, the following tests can be considered:
- Complete blood count (CBC) with red cell indices to evaluate for anemia and reticulocyte count to screen for hemolysis or blood loss 5
- Reticulocyte hemoglobin content (CHr) to diagnose iron deficiency and monitor iron therapy 3
- Endoscopic evaluation to rule out gastrointestinal lesions, although the yield may be low in the absence of visible bleeding 2
- Iron studies, including serum iron, ferritin, and transferrin saturation, to evaluate for iron deficiency anemia 3, 4
CT Angiogram
A CT angiogram may not be the initial test of choice to evaluate for bleeding, given the patient's stable condition and the absence of visible bleeding. However, it can be considered if other investigations are inconclusive or if there is a high suspicion of bleeding 2. The decision to perform a CT angiogram should be based on the patient's clinical presentation and the results of other diagnostic tests.