A 49-yeаr-оld femаle with а histоry оf peptic ulcer disease, celiacs disease, and arthritis who takes over the counter ibuprofen everyday presents to the ED with complaints of severe fatigue and weakness that has been progressive over the past several weeks. She now feels like even after sleeping a full night she wakes up tired and finds it difficult to get out of bed because of the fatigue. A CBC is completed and shows a WBC of 5,600/mcL, RBC 3.1 million/mcL, Hgb 7.9 g/dL, Hct 28%, and plts 200,000 K/mcL. All of the following are risk factors for the development of anemia EXCEPT.
An 80-yeаr-оld femаle with а histоry оf rheumatoid arthritis and recent diagnosis of Non-Hodgkin lymphoma presents to the ED with complaints of severe lower back pain which has become progressively worse over the past several weeks. She also describes lower extremity weakness and ataxia that started several days ago. While being evaluated it is found that she is retaining urine. A bladder scan shows 800cc of urine within her bladder that is then evacuated. Which of the following is the next BEST diagnostic test for further work-up?