Effect of increased levothyroxine dose on depressive mood in older adults undergoing thyroid hormone replacement therapy.
OBJECTIVE
Depressive mood consequent to hypothyroidism can be reversed with levothyroxine (LT4) replacement therapy. However, it is unclear whether increasing LT4 dose confers additional mood benefits.


DESIGN AND PATIENTS
A single-blinded before-and-after study of 24 patients with hypothyroidism who were aged 65 years or older and undergoing LT4 replacement therapy with stable doses.


MEASUREMENTS
Geriatric Depression Scale (GDS-K) and Hyperthyroid Symptom Scale (HSS-K) were assessed at baseline, 3 months after increasing LT4 dose by an additional 12.5 µg/d, and finally 3 months after returning to the baseline dose.


RESULTS
Serum thyroid-stimulating hormone (TSH) concentrations decreased at the higher LT4 dose (1.95 ± 2.16 vs 0.47 ± 1.09 mIU/L, P < .001) and recovered after returning to the baseline dose. Serum-free thyroxine levels and HSS-K scores were unchanged during the study period. GDS-K scores improved on the increased dose (9.5 ± 6.6 vs 7.5 ± 4.7, P = .029), and this improvement was maintained after returning to the baseline dose (9.5 ± 6.6 vs 7.4 ± 5.4, P = .010). Higher serum TSH was independently associated with both higher GDS-K and depression risk among those with depressive mood (GDS-K > 10) at baseline.


CONCLUSIONS
Depressive mood improves with increased LT4 dose, without significant hyperthyroid symptoms or signs, in older adults undergoing thyroid hormone replacement. These findings suggest the potential for varying the treatment target for hypothyroidism based on mood status and that low-dose LT4 treatment might be an ancillary treatment for depression.
['Moon|Jae Hoon|JH|0000-0001-6327-0575', 'Han|Ji Won|JW|', 'Oh|Tae Jung|TJ|', 'Choi|Sung Hee|SH|', 'Lim|Soo|S|0000-0002-4137-1671', 'Kim|Ki Woong|KW|', 'Jang|Hak Chul|HC|']
D000368:Aged D003863:Depression D020249:Hormone Replacement Therapy D006801:Humans D007037:Hypothyroidism D013972:Thyrotropin D013974:Thyroxine
levothyroxine depression hypothyroidism geriatrics affect therapeutics thyrotoxicosis