Leipzig. The thyroid changes with age. “The iodine intake falls, the synthesis of free T4 and T3 is declining, TSH levels are rather increased,” said Professor Karin Frank-Raue. In addition, there are fewer symptoms with increasing age – both in hyperthyroidism and in hypothyroidism, according to the endocrinologist from Heidelberg. In one study, patients over the age of 60 with proven hyperthyroidism showed no or at most two symptoms of hyperfunction. This was also true when excluding patients who were already on β-blockers or amiodarone (1). “Hyperthyroidism can hardly be diagnosed clinically here,” warned Frank-Raue.
Calcium balance becomes negative
The endocrinologist explained the effects this can have by looking at the bones: “Hyperthyroidism exponentially increases the age-related fracture risk.” Because hyperthyroidism shortens the bone remodeling cycles and increases their frequency. The duration of resorption is prolonged compared to mineralization. In addition, calcium absorption in the intestine is reduced, calcium excretion through the kidneys is increased. The result is a negative calcium balance. The good thing: Bone density is normalizing, at least in younger patients, and hyperthyroidism is being treated. This was the result of a study with women in the premenopause (2).
Menopause increases bone loss
Frank-Raue also addressed the topic of bones and menopause: The bone density of a person reaches its maximum up to the age of 30, after that it goes downhill with a bone density loss of 1% per year. “Menopause accelerates the loss of bone mass,” recalled the endocrinologist. In three years of transmenopause, this loss is 2.5%/year in the spine and 1.8%/year in the femoral neck (3). Hormone replacement therapy (HRT) reduces bone density loss by 0.4% per year.
Talk about cardiovascular risks!
Frank-Raue advised that perimenopause is a good time to talk to patients about risks. This is because menopause accelerates cardiovascular risk: total cholesterol levels rise, LDL-C, central obesity and the metabolic syndrome increase (4). At this point, the endocrinologist relativized the results of the WHI study, which 20 years ago was considered the gravedigger of HRT: The women were on average 63 years old and thus well into the postmenopause. Late initiation of HRT – ten or more years postmenopausal – increases the risk of CHD. However, early initiation of HRT seems to have a protective effect against coronary heart disease. “Age makes the difference,” says Frank-Raue.
Menopause or Hyperthyroidism?
Based on a casuistry, the endocrinologist warned of possible overtreatment of hypothyroidism. The 49-year-old patient complained of increased sweating – both constantly and in fits and starts – and asked whether it was the menopause or hyperthyroidism. The anamnesis showed irregular cycles with longer breaks. And the patient had gained 5kg in the past two years. The ultrasound showed a small, hypoechoic thyroid gland. The laboratory: TSH 8.4 mIU/l, TPO antibodies 600 U/ml and FSH 68 U/l. The diagnosis is Hashimoto’s thyroiditis, latent hypothyroidism, perimenopause, according to Frank-Raue.
TSH suppression increases mortality
The patient was treated with L-thyroxine (75 µg//day), initially half a tablet for three weeks. After three months, the TSH value was 2.4 mIU/l, so the patient was well adjusted. The control after six months showed a TSH of 0.01 mIU/l. “What happened?” the endocrinologist asked the participants of the training event and gave the answer straight away: The patient had doubled the L-thyroxine dose in the hope of losing more weight. “That didn’t work, but the patient increased her risk profile drastically,” said Frank-Raue. “Long-term TSH-suppressive therapy has consequences.” The resting heart rate increases, there are more arrhythmias, the pumping function of the heart decreases under stress and bone density decreases. “And a suppressed TSH increases mortality,” warned Frank-Raue (5).
Literature:
1. Boelaert K et al. Older Subjects with Hyperthyroidism Present with a Paucity of Symptoms and Signs: A Large Cross-Sectional Study. JCEM 2010; 95:2715
2. Vestergaard P, Mosekilde L: Hyperthyroidism, bone mineral, and fracture risk–a meta-analysis. Thyroid 2003; 13:585-93
3. Karlamangla AS et al.: Bone Health During the Menopause Transition and Beyond. Obstet Gynecol Clin North Am 2018;45:695-708
4. El Khoudary SR et al.: Menopause Transition and Cardiovascular Disease Risk: Implications for Timing of Early Prevention: A Scientific Statement From the American Heart Association. circulation 2020; 142:506-532
5. Parle JV et al.: Prediction of all-cause and cardiovascular mortality in elderly people from one low serum thyrotropin result: a 10-year cohort study. Lancet 2001; 358:861)
More information on the subject at: www.infoline-thyroid.de
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Source: Event: Thyroid Update 2022, September 28, 2022 in Leipzig and online; Organizer: Sanofi (Henning)