Hematologic effects of levothyroxine in iron-deficient subclinical hypothyroid patients: a randomized, double-blind, controlled study.
BACKGROUND
In patients with coexisting iron-deficiency anemia and subclinical hypothyroidism, anemia does not adequately respond to oral iron therapy.


OBJECTIVE
We studied whether iron-deficiency anemia might indicate treatment of subclinical hypothyroidism.


METHODS
PATIENTS were assigned to a control or experimental group: 240 mg/d oral iron alone (iron group) or 240 mg/d oral iron plus 75 microg/d levothyroxine (iron/levothyroxine group). Levels of hemoglobin, hematocrit, red blood cell count, serum iron levels, ferritin, total iron-binding capacity, TSH, and free T(4) were measured before and after treatment.


METHODS
The study was conducted at a university hospital outpatient clinic.


METHODS
Fifty-one patients with coexisting iron-deficiency anemia and subclinical hypothyroidism participated in the study.


METHODS
PATIENTS were treated as described above in either the iron group or the iron/levothyroxine group.


METHODS
A clinically satisfactory increase in hemoglobin was regarded as successful.


RESULTS
Mean hemoglobin levels increased by 0.4 g/dl in the iron group [95% confidence interval (CI) 0.2-0.7, P = 0.001], whereas it increased by a mean of 1.9 g/dl in the iron/levothyroxine group (95% CI 1.5-2.3, P < 0.0001). The increase in serum iron was greater in the iron/levothyroxine group by a mean of 47.6 microg/dl (95% CI 34.5-60.6, P < 0.0001). Increases in hemoglobin, red blood cells, hematocrit, and serum ferritin levels after treatment were statistically significantly greater in the iron/levothyroxine group (P < 0.0001). Starting hemoglobin and increase in hemoglobin were negatively correlated in the iron/levothyroxine group (r = -0.531, P = 0.006).


CONCLUSIONS
Subclinical hypothyroidism should be treated in iron-deficiency anemia patients when both conditions coexist. This would provide a desired therapeutic response to oral iron replacement and prevent ineffective iron therapy.
Cinemre
Hakan
H
Department of Internal Medicine, Duzce University School of Medicine, Duzce 81620, Turkey. cinemre_h@ibu.edu.tr
Bilir
Cemil
C
Gokosmanoglu
Feyzi
F
Bahcebasi
Talat
T
D000328:Adult; D018798:Anemia, Iron-Deficiency / Q000097:blood / Q000188:drug therapy*; D004311:Double-Blind Method; D005260:Female; D006454:Hemoglobins; D006801:Humans; D007037:Hypothyroidism / Q000097:blood / Q000188:drug therapy*; D008297:Male; D008875:Middle Aged; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000627:therapeutic use*
D006454:Hemoglobins; D013972:Thyrotropin; D013974:Thyroxine