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A 50-year-old man comes to his family physician complaining of fatigue.


The patient indicates that climbing the stairs leaves him short of breath and that this has been getting progressively worse over the past month. He does not participate in any regular exercise. The patient works in a stressful job and to relieve stress the patient smokes, drinks 6 cups of coffee a day, and has two or three alcoholic drinks after work. He has been taking aspirin for the last 6 months for frequent stomach pain. The patient has decreased caloric intake for the past 3 months in an effort to lose weight, with moderate success.



PHYSICAL EXAMINATION



VS: T 36°C, P 105/min, R 24/min, BP 90/75 mm Hg, BMI 33

PE: Upper and lower endoscopy reveals a bleeding gastric ulcer.


LABORATORY STUDIES



Hematocrit: 30%

Red blood cell smear: Microcytic hypochromic cells

Serum iron values: 27 μg/dL

Transferrin saturation: 13%

Serum ferritin: 20 μg/L

Stool test: Positive for occult blood


DIAGNOSIS


Iron deficiency anemia



PATHOPHYSIOLOGY OF KEY SYMPTOMS


The patient’s fatigue and shortness of breath when exercising are characteristic of anemia, confirmed by the finding of a low hematocrit. Gastrointestinal bleeding is the most common type of blood loss leading to an iron deficiency.


Hematocrit reflects the balance of red blood cell synthesis and red blood cell loss. Red blood cell synthesis occurs in the bone marrow and is stimulated by the renal hormone erythropoietin. Loss of red blood cells is usually due to destruction within the spleen and liver. Hemorrhage also results in a loss of red blood cells. If the red blood cell synthesis rate is not sufficient to keep up with the loss from hemorrhage, anemia will result.


Iron is essential for synthesis of hemoglobin. As body iron stores are depleted, hemoglobin synthesis is impaired, and, consequently, the red blood cells have diminished pigment and are termed “hypochromic.” The iron deficiency also results in smaller than normal red blood cells, termed “microcytic.” Severe iron deficiency is characterized by low hematocrit and the appearance of red blood cells as hypochromic and microcytic. It occurs when the hematocrit has fallen below 30%.


The normal lifespan of red blood cells is approximately 120 days. As red blood cells age, their membranes become more rigid, and thus the red blood cells rupture as they pass through the sinusoids of the spleen. The iron and hemoglobin released by the ruptured red blood cells are scavenged by transferrin and haptoglobin, respectively.


The remaining patient symptoms are also due to the hemorrhage. This includes the hypotension and the sympathetically mediated increase in heart rate and respiratory rate. Aspirin and alcohol intake increases the risk of gastrointestinal bleeding, and the presence of the gastrointestinal hemorrhage is indicated by the positive stool test for occult blood and confirmed by the endoscopy.

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Jul 4, 2016 | Posted by in PHYSIOLOGY | Comments Off on 28

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