Vitamin B12 levels are not affected by radioiodine ablation of the thyroid.
OBJECTIVE
Radioiodine administered for the treatment of hyperthyroidism and thyroid cancer can be taken up by many non-thyroid tissues which express sodium iodide symporter. Though gastric mucosa takes up radioiodine, its impact on parietal cell has not been evaluated. The aim of the present study was to compare vitamin B12 and homocysteine concentrations in patients with thyroid disorders treated by radioiodine ablation with those in control population without radioiodine exposure.


METHODS
Patients with Graves' disease, toxic multinodular goiter (TMNG), toxic adenoma (TA) or differentiated thyroid cancer (DTC) who had received 131I were included as "patients". Healthy persons and patients having Graves' disease but without exposure to radioiodine were recruited as "controls". A total of 35 patients and 35 controls were included. Patients were divided into Graves' disease and non-Graves' disease (TMNG, TA, DTC) groups. Graves' disease patients were compared with Graves' disease controls while non-Graves' disease patients were compared with healthy controls.


RESULTS
In the Graves' disease group, median vitamin B12 concentration was 240 pg/ml (IQR: 148 - 371) in patients (n=23) and 195 pg/ml (IQR: 140 - 291 pg/ml) (p=0.13, ns) in controls (n=24). In the non-Graves' disease group, median serum vitamin B12 concentration was 147 pg/ml (IQR: 124 - 325pg/ml) in patients (n=12) and 190 pg/ml (IQR: 157 - 373 pg/ml) (p=0.34, ns) in healthy controls (n=11). Homocysteine concentrations were also similar in compared groups of patients and controls.


CONCLUSIONS
Radioiodine ablation does not cause vitamin B12 deficiency. However, a prospective study with a larger number of patients is required to confirm this finding.
S K
SK
Potham
S
S
Vaikkakara
A
A
Sachan
S P V L N
SP
Rao
T C
TC
Kalawat
P
P
Ravi
E
E
Sunil
D
D
Rajitha
M
M
Arun
A
A
Sailaja
D000236:Adenoma / Q000097:blood / Q000532:radiotherapy*; D000328:Adult; D000368:Aged; D018265:Carcinoma, Papillary, Follicular / Q000097:blood / Q000532:radiotherapy*; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005260:Female; D006044:Goiter, Nodular / Q000097:blood / Q000532:radiotherapy*; D006111:Graves Disease / Q000097:blood / Q000532:radiotherapy*; D006710:Homocysteine / Q000097:blood; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D013964:Thyroid Neoplasms / Q000097:blood / Q000532:radiotherapy*; D014805:Vitamin B 12 / Q000097:blood*
D007457:Iodine Radioisotopes; D006710:Homocysteine; D014805:Vitamin B 12