As a pharmacy specialist, you should avoid many older adults to get too much levothyroxine (Synthroid, Euthyrox, Eltroxin, etc), increasing their risk of atrial fibrillation and fractures. Levothyroxine requirements decrease as people age, but doses are often not reduced accordingly.
Younger adults need about 1.7 mcg/kg/day of levothyroxine, but some seniors need only 0.5 mcg/kg/day. About 25% of patients on too much levothyroxine develop Atrial fibrillation within 10 years, and patients over 70 are about twice as likely to have a fracture if they are on levothyroxine. Recommend starting seniors at 25 mcg/day or less of levothyroxine. Suggest checking TSH at least once a year, and 6 to 8 weeks after a dose change.
Advise patients to report symptoms of overtreatment, increased pulse, sweating, weight loss, irritability, fatigue, etc. Keep in mind that increased pulse and sweating can be masked by beta-blockers (Inderal, Concor, etc) and weight loss, irritability, and fatigue can be mistaken for depression in older patients.
REFERENCES
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Turner MR, Camacho X, Fischer HD, Austin PC, Anderson GM, Rochon PA, Lipscombe LL. Levothyroxine dose and risk of fractures in older adults: nested case-control study. BMJ. 2011 Apr 28;342:d2238. Available at: https://www.bmj.com/content/342/bmj.d2238
Flynn RW, Bonellie SR, Jung RT, MacDonald TM, Morris AD, Leese GP. Serum thyroid-stimulating hormone concentration and morbidity from cardiovascular disease and fractures in patients on long-term thyroxine therapy. J Clin Endocrinol Metab. 2010 Jan;95(1):186-93. Available at: https://academic.oup.com/jcem/article/95/1/186/2835226?login=false