In order to search for the pathophysiology of anemia, authors investigated 43 cases of
hypothyroidism.
1. Anemia was observed in 60% (26/43), In which the thyroid hypofunction was more
severe than that in the non-anemia group.
2. In anemia group the normocytic anemia was the most frequent(50% ), followed by
microcytic(27% ) and macrocytic(23% ) anemia in frequency. In majority of cases(85%),
the anemia was mild, and the degree of anemia was most pronounced in microcytic
type, while the tendency of thyroid hypofunction was more marked in macrocytic group.
3. The serum Iron and iron saturation were reduced in 53% (9/17) of anemic cases.
There noted 1 case of folate deficiency(1/15) and no cases with vitamin Bl2
deficiency(0/l5).
4. The bone marrow cellularity was decreased in 44% of 16 examined and in 87%, the
stainable iron was decreased with no cases of megaloblastic maturation.
5. Of the 16 anemia cases, the uncomplicated anemia and iron deficiency anemia were
8(50%), respectively, and the bone marrow hypocellularity was more frequently
encountered in uncomplicated anemia(63% ) than in iron deficiency anemia(25%). The
stainable iron of bone marrow was decreased In 71% of uncomplicated anemia without
cases of microcytosis.
6. The erythropoietin(EPO) level tends to Increase In microcytic/iron deficiency anemia,
and normal in macrocytic/uncomplicated anemia group. The hemoglobin correlated with
serum iron & iron saturation, and inversely correlated with EPO. And the EPO inversely
correlated with serum iron and iron saturation.
7. The CFU-E colony formation was increased in anemia compared to that in control,
while there was no difference in BFU-E growth.
With the above results, the uncomplicated anemia of hypothyroidism might be caused
by decreased hematopoiesis depending on EPO activity with which the hormonal status
met the body's requirements, while more compensatory hemopoiesis might be elicited in
iron deficiency anemia.

Keywords: Anemia in Hypothyroidism, Pathophysiology, Bone marrow, Erythropoietin, Erythroid clonogenic assaay