What is the appropriate management for a 50-year-old patient presenting with headache, body weakness, anemia, and bone pain, with normal blood pressure and normal oxygen saturation?

Diagnostic Workup for Anemia with Bone Pain in a 50-Year-Old Patient

This patient requires urgent evaluation for multiple myeloma given the constellation of anemia (Hb 9.8 g/dL), bone pain, headache, and age 50, with immediate laboratory workup including serum protein electrophoresis (SPEP), serum free light chains, complete blood count with differential, comprehensive metabolic panel, calcium level, and bone marrow biopsy if initial screening is positive. 1

Immediate Diagnostic Priorities

Rule Out Multiple Myeloma First

• The combination of anemia, bone pain, and age 50 is highly suspicious for multiple myeloma, which commonly presents with this triad and requires urgent diagnosis to prevent complications such as pathologic fractures, hypercalcemia, and renal failure 1
• Order SPEP with immunofixation and serum free light chain assay immediately, as these are the primary screening tests for plasma cell dyscrasias 1
• Check serum calcium level urgently, as hypercalcemia is a common and dangerous complication of myeloma that can cause headache and weakness 1
• Obtain comprehensive metabolic panel to assess renal function, as myeloma kidney is a frequent complication 1
• Perform skeletal survey (plain radiographs of skull, spine, pelvis, and long bones) to identify lytic bone lesions characteristic of myeloma 1

Complete Anemia Workup

• Obtain complete blood count with differential to assess for pancytopenia or other cell line abnormalities that might suggest bone marrow infiltration 2, 3, 4
• Check reticulocyte count to determine if anemia is hypoproliferative (low reticulocyte count suggesting bone marrow failure) or hyperproliferative (high reticulocyte count suggesting hemolysis or blood loss) 2, 3
• Order iron studies (serum iron, ferritin, total iron-binding capacity, transferrin saturation) to evaluate for iron deficiency anemia or anemia of chronic disease 1, 3
• Measure vitamin B12 and folate levels to exclude megaloblastic anemia 2, 3
• Obtain peripheral blood smear to look for rouleaux formation (stacks of red cells suggesting high protein levels in myeloma) or other morphologic abnormalities 2, 3

Secondary Diagnostic Considerations

If Myeloma Screening is Negative

• Consider other causes of normocytic anemia with bone pain, including metastatic cancer, lymphoma, or bone marrow infiltrative disorders 2, 4
• Evaluate for chronic kidney disease as a cause of anemia, checking creatinine and estimated glomerular filtration rate 1
• Screen for gastrointestinal blood loss with stool occult blood testing and consider endoscopy if positive, particularly in the setting of iron deficiency 1
• Check thyroid function tests, as hypothyroidism can cause anemia and fatigue 3
• Obtain erythrocyte sedimentation rate and C-reactive protein to assess for inflammatory conditions 3

Bone Pain Evaluation

• If skeletal survey is negative for lytic lesions, consider MRI of symptomatic areas to evaluate for bone marrow infiltration, fractures, or other pathology 1
• Assess for osteoporosis or osteomalacia with bone density testing and vitamin D level if myeloma is excluded 5

Immediate Management While Awaiting Results

Symptomatic Treatment

• Do not transfuse unless hemoglobin falls below 7 g/dL or patient develops cardiovascular instability, as this patient's Hb of 9.8 g/dL with normal vital signs does not meet transfusion criteria 6, 7
• Provide analgesics for bone pain, starting with acetaminophen or NSAIDs if renal function is normal 1
• Address headache with appropriate analgesics while investigating underlying cause 1

Iron Supplementation Considerations

• If iron deficiency is confirmed (ferritin <45 ng/mL in setting of anemia), initiate oral iron supplementation with ferrous sulfate 325 mg daily on an empty stomach, as this is first-line therapy for iron deficiency anemia 1
• Consider intravenous iron if oral iron is not tolerated or if there is evidence of malabsorption 1

Critical Next Steps Based on Results

If Myeloma is Confirmed

• Refer urgently to hematology-oncology for bone marrow biopsy with cytogenetics and FISH analysis to stage disease and guide treatment 1
• Initiate treatment with triplet therapy (lenalidomide-bortezomib-dexamethasone or daratumumab-lenalidomide-dexamethasone) if high-risk features are present 1
• Begin bisphosphonate therapy to prevent skeletal complications 1

If Alternative Diagnosis is Found

• Treat underlying cause appropriately (iron supplementation for iron deficiency, vitamin B12 for megaloblastic anemia, erythropoiesis-stimulating agents for chronic kidney disease, etc.) 1

Common Pitfalls to Avoid

• Do not dismiss bone pain as simple arthritis or musculoskeletal pain in a patient with unexplained anemia, as this combination warrants investigation for serious underlying pathology 1
• Do not delay myeloma workup by treating anemia empirically with iron or B12 without first obtaining diagnostic studies, as this can mask the underlying diagnosis 1, 2
• Do not assume anemia is due to iron deficiency without confirming with iron studies, as anemia of chronic disease from myeloma can present similarly 1, 2
• Do not overlook hypercalcemia as a cause of headache and weakness in this clinical context, as it requires urgent treatment 1