Iets over ouderen en minder levothyroxine nodig staat in onderstaand artikel.
Ik zal de belangrijkste quote hieronder zetten, met de bijbehorende literatuurtitels.
De halfwaardetijd van levothyroxine is dus ook verlengd bij ouderen.
Dat betekent dat je een maand of twee moet wachten, voordat je met de TSH/FT4 een beeld hebt van je waarden met de dosis van dat moment.
High Frequency of and Factors Associated with Thyroid Hormone Over-Replacement and Under-Replacement in Men and Women Aged 65 and Over
Lily L Somwaru, Alice M. Arnold, Neha Joshi, Linda P. Fried, and Anne R. Cappola
JCEM 2009
“It has been reported that older hypothyroid patients need approximately 25% less T4 than younger patients (7, 8). Not only is there a decrease in the secretion of thyroid hormone with increasing age (9,10), but the half-life of T4 also increases with age, with a meanhalf-life of 6.7 d for adults aged 18-27 year of age, and approximately 9 d for those aged 65 yr and older (9). Together, these data suggest that older individuals should be initiated on lower doses of T4 replacement and that a longer duration may be required between dose titrations. Furthermore, continued monitoring is necessary to assess for decreasing thyroid hormone requirements over time. “
7. Rosebaum RL, Barel US 1982 Levothyroxine replacement dose for primary hypothyroidism decreases with age. Ann Intern Med 96:53—55
8. Sawin CT. Herman T. Molitch ME, London MH. Kramer SM 1983 Aging and the thyroid. Decreased requirement for thyroid hormone in older hypothyroid patients. Am J Med 75:206-209
9. Gregerman R, Caffney G, Shock N, Crowder S 1962 Thyroxine turnover in euthyroid man with special reference to changes with age. J Clin lnvest 41: 2065-2074
10. Oddie TH, Meade Jr JH, Fisher DA 1966 An analysis of publshed data on thyroxine turnover in human subjects. J Clin Endocrinol Metab 26:425-436
De hele tekst is te lezen op:
http://jcem.endojournals.org/cgi/reprint/94/4/1342