ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Endocrine Abstracts (2008) 16 P791

Cognitive dysfunctions during chronic thyrotropin-suppressive therapy with levothyroxine in patients with differentiated thyroid carcinoma

Katarzyna Lacka1, Aleksandra Kucharska2, Aleksandra Rajewska-Rager2 & Jan Jaracz2

1Department of Endocrinology, Metabolism and Internal Medicine, Poznan, Poland; 2Department of Adult Psychiatry, Poznan, Poland.

Background: TSH-suppressive therapy is widely used in treatment of thyroid differentiated carcinoma. A common consequence of therapy is subclinical hyperthyroidism which may cause dysfunction of cardiovascular system, metabolism and reduction of bone mass1. Thyroid hormones are also involved in regulation of brain function2. Therefore, it is not surprising that thyroid dysfunctions are associated with frequent comorbid cognitive dysfunctions and depression.

The aim of our study was to assess the cognitive functions in patients treated with suppressive doses of levothyroxine due to thyroid papillary carcinoma.

Method: Twenty-eight patients with subclinical hyperthyroidism in the course of substitutive treatment with levothyroxine due to total thyroidectomy and 131I therapy were involved in the study. The control group consisted of 17 healthy, euthyroid subjects. A battery of neuropsychological tests was administered to assess: 1. Working memory and executive functions (the Wisconsin Card Sorting Test – WCST, The Controlled Oral Word Association Test-FAS), 2. psychomotor speed (the Trial Making Test – TMT) 3. attention (the Stroop test) and 4. Short term memory (the Digit Span test). Psychometric evaluation was made using 17 items the Hamilton Depression Rating Scale and Beck Depression Inventory.

Results: Patients compared to control group performed poorer in WCST. They made significantly more perseverative errors. Patients were found to perform less well than controls in FAS and in TMT-B. The mean score of HDRS and BI (3.4 and 6.6 respectively) suggest that patients were not depressed during examination.

Conclusion: Our results suggest that suppressive treatment with levothyroxine may affect executive functions, working memory, psychomotor speed.

1. Biondi B, Palmieri EA, Klain M, Schlumberger M, Filetti S & Lombardi G. Subclinical hyperthyroidism: clinical features and treatment options. Eur J Endocrinol 2005 152 1–9.

2. Smith JW, Evans T, Costall B & Smythe JW. Thyroid hormones, brain function and cognition: a brief review. Neurosci Biobehav Rev 2002 26 45–60.

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