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Remember the hormones: second lesson learned from an elderly patient with dementia
This patient was described in the November issue.
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A 74-year-old woman is accompanied by her daughter for an initial consultation. She had been referred by her geriatrician in the context of worsening dementia.
The patient has a history of thyroidectomy and radioactive iodine ablation in her 20s for thyroid cancer; there has been no recurrence since, and she has not seen an endocrinologist in years. In addition to postsurgical hypothyroidism, she also has a history of vitamin D deficiency, impaired memory and arthritis. Surgical history is notable for total knee arthroplasty, appendectomy, hysterectomy and cataract removal.
On review of symptoms, she reports fatigue, cold intolerance and feeling “slow,” and denies palpitations, heat intolerance, weight change, nervousness, jitteriness, labile mood, hair loss, gastrointestinal symptoms and hoarseness. The daughter is concerned about her mother’s impaired memory.
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She does not come with a medication list but reports adherence to the prescribed medical regimen of levothyroxine 50-mcg daily, conjugated estrogens 0.625-mg daily and vitamin D and calcium; she denies drug allergies. Family history is positive for acquired hypothyroidism. The patient is a widow and lives alone but within driving distance from her daughter. She does not smoke and has one drink per day. She is a retired typist.
The patient is barely participatory on the conversation and appears absent and withdrawn. Most history is submitted by the daughter, who then coaxes her mother to either agree or disagree.
On exam, her blood pressure is 140 mm Hg/90 mm Hg, pulse 96, weight 123 lb, BMI 21. The patient has a scar after thyroidectomy and no palpable thyroid tissue. She has normal judgment and insight, appears oriented to time and person but is not completely oriented to place. Physical exam is otherwise unremarkable.
On review of labs, thyroid-stimulating hormone was 0.09 mIU/L four months before the visit. The patient reduced her levothyroxine dose to five times per week, and a subsequent TSH one month later (three months before this visit) was 5.5 mIU/L. She is currently taking one tablet of levothyroxine daily.
Patient and daughter leave the practice, and labs come back later that night: TSH was elevated at 114 mIU/L.
What is the next best step?
A. Double the levothyroxine dose the patient has reported and call in a prescription for 100 mcg by mouth daily.
B. Nothing; the literature shows that elderly patients live longer when they are hypothyroid. She’ll thank you with a card on her 120th birthday.
C. Call the pharmacy to verify the dose of levothyroxine and when it was last filled — then call the patient and ask how she usually takes her pill.
D. Start fluoxetine for depression.
E. Have the patient come back right away and give levothyroxine 500-mcg IV stat.
Case Discussion:
This is a mildly disoriented elderly woman with a history of postsurgical hypothyroidism and an old lab report with a mildly elevated TSH, indicating mild hypothyroidism at the time. She states that she addressed the matter on her own by going back to taking her low dose of thyroid hormone daily instead of five times a week, and one would therefore expect a much lower TSH. This case illustrates that profound hypothyroidism does not necessarily need to be accompanied by debilitating disease. However, despite some reports in the literature that mild hypothyroidism is associated with increased longevity in the very elderly (B), this patient’s health and life is quite impaired and the TSH of 114 mIU/L must be addressed before assuming primary depression (D). Under no circumstance does her situation warrant IV injection of a high dose of thyroid hormone because this would merely increase her risk for enduring cardiovascular adverse effects (E).
Instead, she requires more levothyroxine by mouth. However, before a dose can be set (A), one needs to find out more about whether she has been taking her medication as prescribed. When I called the patient at home, she read the label to me, and it turns out that she had misremembered the dose: She was taking 200-mcg daily, not 50-mcg. In this setting, prescribing 100-mcg daily would have actually worsened her condition (A). More importantly, I asked her when and how she was taking her medication. It turned out that she took all her pills with breakfast, meaning that her calcium carbonate tablets (and possibly some breakfast ingredients) were impairing absorption of levothyroxine. I therefore instructed her to take her levothyroxine 30 to 60 minutes before breakfast, separate from all other pills, and I asked her daughter to come by the house every day for a while to make sure the mother was taking her pills properly. Because it was impossible to determine how severely the calcium and breakfast impaired absorption, I continued the current levothyroxine dose of 200-mcg daily.
One month later, the patient returned for follow-up. She was a new person and was much more engaged in the conversation, no longer appeared depressed and appeared to have much better memory. Her TSH had decreased to 0.08 mIU/L, so we reduced her dose of thyroid hormone, and she was alert enough to take her medication properly on her own.
Ronald Tamler, MD, PhD, MBA, is Assistant Professor in the Division of Endocrinology at Mount Sinai School of Medicine, N.Y.
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