Effect of adjuvant lithium on thyroxine (T4) concentration after radioactive iodine therapy.
OBJECTIVE
To study the effect of adjuvant lithium on serum thyroxine (T4) concentrations in patients treated with radioactive iodine (RAI) therapy in our environment.


METHODS
This was a prospective simple randomized comparative, experimental cohort study of patients with hyperthyroidism referred for RAI ablation therapy in the two main academic hospitals in Johannesburg between February 2014 and September 2015.


RESULTS
Amongst the 163 participants in the final analysis, 75 received RAI alone and 88 received RAI with lithium. The difference in mean T4 concentrations at 3 months between the RAI-only group (17.67 pmol/l) and the RAI with lithium group (11.55 pmol/l) was significant with a small effect size (U = 2328.5, Z = -2.700, p = 0.007, r = 0.01). Significant decreases in T4 concentrations were observed as early as 1 month after RAI (p = 0.0001) in the RAI with lithium group, but in the RAI-only group, significant decreases in T4 concentrations were observed only at 3 months after RAI therapy (p = 0.000). Women and patients with Graves' disease who received RAI with adjuvant lithium also showed significant decreases in T4 concentrations at 1 month (p = 0.002 and p = 0.003, respectively).


CONCLUSIONS
Adjuvant lithium leads to an earlier and better response to RAI therapy with lower T4 concentrations that are achieved earlier. This earlier response and decrease in T4 concentrations were noted in patients with Graves' disease and nodular goitre, and in women with hyperthyroidism who received adjuvant lithium therapy.
Division of Nuclear Medicine and Molecular Imaging, Department of Radiation Sciences, University of the Witwatersrand, 7 York Road, Parktown, 2193, Johannesburg, South Africa. niiboyehammond@gmail.com.
Emmanuel NiiBoye
EN
Hammond
Division of Nuclear Medicine and Molecular Imaging, Department of Radiation Sciences, University of the Witwatersrand, 7 York Road, Parktown, 2193, Johannesburg, South Africa.
Mboyo-Di-Tamba Heben Willy
MD
Vangu
D000328:Adult; D015415:Biomarkers / Q000097:blood; D059186:Chemoradiotherapy, Adjuvant / Q000379:methods*; D017024:Chemotherapy, Adjuvant / Q000379:methods; D005260:Female; D006801:Humans; D006980:Hyperthyroidism / Q000097:blood* / Q000175:diagnosis / Q000628:therapy*; D018020:Lithium Compounds / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013019:South Africa; D013974:Thyroxine / Q000097:blood*; D016896:Treatment Outcome
D015415:Biomarkers; D018020:Lithium Compounds; D013974:Thyroxine
Hyperthyroidism; Lithium; Radioactive iodine ablation; Thyroxine