M.H. Samuels 1 , I. Kolobova 3 , M. Niederhausen 2 , J. Janowsky 4 , K. Schuff 1
Endocrinology, Diabetes and Clinical Nutrition, Oregon Health &
Science University, Portland, OR;
Biostatistics and Design
Program, Oregon Health & Science University, Portland, OR;
Penn State Health St. Joseph, Reading, PA;
The brain is a critical target organ for thyroid hormone, but it is not clear whether variations in thyroid function within and near the laboratory reference range (indicated by high-normal or mildly elevated TSH levels) affect quality of life, mood, or cognitive function.
138 subjects with L-T4 treated primary hypothyroidism and normal TSH levels underwent baseline measures of quality of life (SF-36, ThyDQoL), mood (Profile of Mood States, Affective Lability Scale), and cognition (declarative and working memory, motor learning, executive function). They were then randomly assigned to receive their usual L-T4 dose or a higher or lower dose in double blind fashion, targeting one of three TSH ranges (Low-Normal TSH (0.34–2.50 mU/L), High-Normal TSH (2.51–5.60 mU/L), or Mildly Elevated TSH (5.60–12.0 mU/L)). Doses were adjusted every 6 weeks based on TSH levels.
Quality of life, mood and cognitive tests were reassessed at 6 months. Outcomes were compared among the three groups using mixed models or multiple logistic regressions. At end of study, mean L-T4 doses were 1.52 – 0.06, 1.10 – 0.10, and 0.92 – 0.08 mcg/kg (p<.001), and mean TSH levels were 1.34 –0.08, 3.74 –0.12, and 9.74 – 0.63 mU/L (p < .001) in the Low-Normal TSH, High-Normal TSH, and Mildly Elevated TSH groups.
There were minor differences in a few outcomes among the three groups (SF-36 bodily pain best in the High-Normal TSH group (p =.04),1-Back best in the Low-Normal TSH group (p = .004)), but no clinically meaningful effects in any outcomes. Subjects preferred L-T4 doses they perceived to be higher (p<.001), but not actual higher L-T4 doses (p=0.54). Altering L-T4 doses in L-T4 treated subjects to achieve low-normal TSH levels (vs high-normal or mildly elevated levels) does not significantly improve quality of life, mood, or cognition. L-T4 treated subjects prefer perceived higher L-T4 doses despite a lack of objective benefit from actual higher L-T4 doses.
Adequately treated hypothyroid patients’ reports of symptoms in these areas should not be used as a basis for adjusting L-T4 doses.
http://online.liebertpub.com/doi/pdfplu ... .abstracts