A 55-year-old Caucasian male presents to your office complaining of easy fatigability. He used to be physically active and always preferred to walk to work, which is five blocks away from where he lives. Now he says, "Doc, I get short of breath when I walk even two blocks." He denies any palpitations, chest pain, cough, or lower extremity swelling. He does not feel down and has no problems with sleep. His past medical history is insignificant. He is currently not taking any medications. His blood pressure is 120/70 mm Hg and heart rate is 95/min. The physical examination is significant for pallor of the conjunctivae and oral mucosa. His laboratory values are: Blood smear analysis shows microcytic erythrocytes with anisocytosis. What is the best next step in the management of this patient?

Question

A 55-year-old Caucasian male presents to your office complaining of easy fatigability.  He used to be physically active and always preferred to walk to work, which is five blocks away from where he lives.  Now he says, "Doc, I get short of breath when I walk even two blocks."  He denies any palpitations, chest pain, cough, or lower extremity swelling.  He does not feel down and has no problems with sleep.  His past medical history is insignificant.  He is currently not taking any medications.  His blood pressure is 120/70 mm Hg and heart rate is 95/min.  The physical examination is significant for pallor of the conjunctivae and oral mucosa.  His laboratory values are:  Blood smear analysis shows microcytic erythrocytes with anisocytosis.  What is the best next step in the management of this patient?

Quizplus · Accepted Answer

Explanation: The diagnosis of iron deficiency anemia may not seem straightforward in this patient. Although microcytic/hypochromic anemia with anisocytosis is consistent with iron deficiency anemia, the serum ferritin value could be considered troublesome because the traditional ferritin cutoff point for iron deficiency is 15 ng/mL. Almost all patients with serum ferritin concentrations <15 ng/mL are iron deficient. There is no other clinical situation that explains such an extremely low level of serum ferritin. With the use of a 15 ng/mL cutoff point, the sensitivity of serum ferritin for detecting iron deficiency is 59% and specificity is 99%. However, since the sensitivity of serum ferritin is only 59% with this cutoff, a significant number of patients may have a value which is "borderline low" from 15-30 ng/mL; therefore, a value >15 ng/mL does not exclude the diagnosis. In fact, the sensitivity of serum ferritin rises to 92% when 30 ng/mL is used as the cutoff, and specificity remains similar. One, therefore, needs to be aware that the traditional cutoff of 15 ng/mL for diagnosing iron deficiency anemia is not an absolute. Iron deficiency anemia is not excluded by the ferritin level of 24 ng/mL in this patient; in fact, iron deficiency is the most likely diagnosis given the clinical scenario. The gastrointestinal tract is the major source of blood loss leading to iron deficiency anemia in males; therefore, a fecal occult blood test is a reasonable initial choice for this patient. A series of three fecal occult blood tests helps to maximize the sensitivity of the test, although endoscopy would likely be needed even if negative. Colonoscopy is typically performed before EGD in these patients unless there is a particular reason to suspect an upper gastrointestinal source of bleeding, such as NSAID use. (Choice A) Autoimmune hemolytic anemia is usually normocytic/normochromic. (Choice C) Although thalassemias can manifest as microcytic anemia, these usually present earlier in life, and characteristic findings on the blood smear may be observed ("target cells"). (Choice D) Rheumatoid arthritis causes chronic inflammation and is a common cause of anemia of chronic disease. However, the serum ferritin level is typically normal to elevated in anemia of chronic disease since it is an acute-phase reactant. (Choice E) Vitamin B12 and folate deficiency anemias are usually macrocytic. Educational objective: Almost all patients with serum ferritin concentrations of less than the traditional cutoff of 15 ng/mL are iron deficient. However, the sensitivity using this cutoff is only modest at best and it cannot be used to exclude the diagnosis of iron deficiency since the majority of patients with a level of 15-30 mg/nL are also iron deficient. The gastrointestinal tract is the major source of blood loss leading to iron deficiency anemia in males.

A 55-Year-Old Caucasian Male Presents to Your Office Complaining of Easy