Question

a 17 - year - old female patient presents with fatigue that has been present for several months. in spite of a good diet, methylmalonic acid is elevated. you suspect a lack of intrinsic factor. the gold standard test to confirm or rule out your suspicion is which of the following?
a) mma
b) serum ferritin
c) neutrophilic hypersegmentation rate
d) shilling test
e) serum iron

Explanation:

The Shilling test is used to assess the body's ability to absorb vitamin B12. A lack of intrinsic factor (which is needed for vitamin B12 absorption) can be evaluated with this test. MMA (methylmalonic acid) is already elevated in the patient (so option a is not the confirmatory test). Serum ferritin (option b) is related to iron - storage (not relevant to intrinsic factor - related B12 absorption). Neutrophilic hypersegmentation rate (option c) is a morphological finding in megaloblastic anemias (not the gold - standard test for intrinsic factor deficiency). Serum iron (option e) is related to iron status (not relevant here).

Answer:

d) Shilling Test