archer question 188 - doctor7

[ArchivalUser]

A 24 year old woman is evaluated for a history of chronic anemia. Her history is significant for anemia for the past 7 years. She has been treated with oral iron supplements in the past with out any response. She denies any gastrointestinal bleeding. Her menstrual cycle is 3 days in duration and her menses have been scant for the past 5 years. There is no family history of anemia or bleeding disorder or cancer. Physical examination is unremarkable. Laboratory investigations reveal :
Hemoglobin : 10.6gm%
MCV: 68fl ( normal 80 to 100)
WBC : 8.8K/μl
Platelets: 230k/μl
Red Cell Distribution Width : 12.8% ( 10.2 to 14.5%)
Reticulocyte count : 6% ( normal 0.5% to 1.5%)
Which of the following are most helpful in diagnosing this patient’s anemia?
A) Serum ferritin
B) Bone marrow biopsy
C) Direct Coombs’ test
D) Hemoglobin Electrophoresis
E) Anti-endomysial antibodies
plz help

[ArchivalUser]

let us solve this one by one?
how would you approach an anemia first?
you would look at MCV first , correct? So this pt has microcytic anemia. Next thing about all causes of microcytic anemia. Causes are iron deficiency, thalassemia, anemia of chronic disease and rare ones are spent phase of poly.vera.

Next clue is RDW. RDW predicts the width of the RBC series. If there are different sizes of RBC, RDW will be very high. Iron deficiency is characterized by increased RDW because the size varies highly from small RBC to normal RBC ( ANISOCYTOSIS). But RDW is normal here , that means all the RBC are small at 68fl MCV.

Next clue is reticulocyte count. Retic count is very low in severe iron deficiency because you can not be producing RBC precursors if you do not have iron. Retic may be high in thalssemia due to some degree of hemolysis. So, higher than normal retic or normal retic indicates that there is no nutrient deficiency like iron deficiency. ( This point is reference from Dr.Red hematology lecture)

Answer is thalassemia and therefore, you need HGB electrophoresis. which is most helpful in diagnosing his condition.

[ArchivalUser]

thank u so much misshyd...that was a great explanation

[ArchivalUser]

why not bone marrow biopsy

[ArchivalUser]

bone marrow biopsy is invasive and it wont help you in diagnosis of thalassemia. HGB electrophoresis will show less HGA and increased HGBA2 in beta thalassemia which is confirmative of beta thal. ( HGA made of alpha and beta chains. HGBA2 made of alpha and delta chains. HGF made of alpha and gamma chains. If beta chain is less produced as in beta thal , you will see reduced HGBA and compensating percentage increase in HGBA2 and HGF)

[ArchivalUser]

thanks misshyd...wonder how to r/o direct coombs test here?

[ArchivalUser]

thankzzz, good expln