How common are thyroid disorders in older people and how do symptoms differ in the elderly?

Several studies referring to those over 65 years show that thyroid illness is very much a disease of the elderly and that it often goes undiagnosed. Although the incidence of thyroid problems increases with age, it is sometimes difficult to diagnose as symptoms are not always as widespread or obvious as those in younger patients.

While some of the symptoms of hyperthyroidism and hypothyroidism in older patients are similar to those in younger patients, symptoms of both disorders often manifest in subtle ways in older patients, masquerading as diseases of the bowel or heart or a disorder of the nervous system.

The difficulty in diagnosing older people is that thyroid abnormalities can appear much differently from the way they are supposed to. Whereas hyper- and hypothyroidism present very differently in younger patients, in older patients there are similarities between the two disorders

In both conditions in older people there can be confusion, depression, falling, heart failure and changes in bowel habits. Not only do these signs make it difficult to distinguish hyper- from hypothyroidism in this age group, but they are also signs of common illnesses of older people.

Hyperthyroidism (over-active thyroid) in older people

As in all hyperthyroid patients, if there is too much thyroid hormone, every function of the body tends to speed up. However, while younger people with thyroid disorders often experience multiple symptoms related to the over-active thyroid (weight loss, palpitations, sweating, nervousness, tremors) older people may only have a few symptoms, for example some heart palpitations and chest discomfort on climbing stairs. Others may have a tremor and feel depressed but not have any other symptoms.

Treatment of older people with hyperthyroidism

As with younger people, treatment of hyperthyroidism in older people includes antithyroid drugs and radioactive iodine. Surgery is rarely recommended due to increased risks associated with operations in older people. While Graves’ disease is still a common cause of hyperthyroidism in this age group, toxic nodular goitre (either in the form of multiple nodules or a single over-active nodule), resulting in hyperthyroidism, is more frequent than in younger individuals. The latter is not associated with the eye problems that are sometimes seen in Graves' disease).

During treatment for an over-active thyroid, the effects of change in thyroid function on other body systems are closely monitored, due to an increased likelihood of co-existing diseases – cardiac, central nervous system and thyroid – in older patients. Most often, thyroid function is brought under control first with antithyroid drugs before definitive treatment with radioactive iodine is considered.

During the initial phase of treatment, doctors will check heart function closely due to the effect of changing thyroid hormone levels on the heart. Symptoms of hyperthyroidism may be brought under control with other medications alongside the antithyroid drugs such as beta-blockers, which are often given to slow a rapid heart rate. Definitive treatment with radioactive iodine is considered once thyroid function is maintained in the normal range with oral medication.

Hypothyroidism in the older patient

Hypothyroidism is the most common thyroid condition in patients over 60 years of age and steadily increases with age. A screening study that evaluated more than 25,000 individuals attending a health fair in Colorado revealed that 10% of men and 16% of women age 65-74 had TSH levels that were increased above the upper limit of the reference range, while 16% of men and 21% of women age 75 and older had increased TSH levels.

Unlike symptoms of hyperthyroidism (particularly in younger people), the symptoms of hypothyroidism are very non-specific in all patients, and even more so in older people. The severity and extent of symptoms also depend on the degree of hypothyroidism. As with hyperthyroidism, the frequency of multiple symptoms (dry skin, thinning hair, constipation, weight gain, low mood, tiredness) decreases with age. For example, memory loss or a decrease in cognitive functioning, often attributed to advancing age, may be the only symptom of severe hypothyroidism in an older person. Clues to the possibility of hypothyroidism include a positive family history of thyroid disease, past treatment for hyperthyroidism, or a history of extensive surgery and/or radiotherapy to the neck.

Treatment of older people with hypothyroidism

If older patients have symptoms of hypothyroidism and treatment is needed, the dose of levothyroxine is started gradually and increased cautiously, so as not to put any strain on the heart and central nervous system. Treatment will usually begin with 25 to 50mcg of levothyroxine daily, and the dose increased in steps every 4-6 weeks until the blood tests show a gradual return of thyroid hormone and thyroid-stimulating hormone (TSH) levels to the normal range. Older patients with no evidence of heart disease, stroke or dementia may be started on larger doses (for example, half of the anticipated full replacement dose) and proceed to full hormone replacement more quickly.

Thyroid reference ranges for older patients

It is well known that thyroid hormone requirements change with age and there is currently a debate as to whether the practice of treating everyone with an under- active thyroid in a uniform fashion, regardless of their age, is appropriate. Currently, an increasing number of older people are diagnosed with a mild under-active thyroid (subclinical hypothyroidism) when their blood thyroid hormone levels (T3 and T4) are normal and their TSH levels are high. However, it has been found that TSH levels increase in older people (70+ years of age) and this is not always associated with poorer health. In addition, the standard TSH reference range used has been obtained from mainly younger people and therefore may not be suitable to make a diagnosis of hypothyroidism in older people.

There are a number of studies currently being undertaken to try and pinpoint what TSH levels for older people with an under-active thyroid should be. The SORTED study (Study of Optimal Replacement of Thyroxine in the Elderly) led by Dr Salman Razvi, Senior Lecturer and Consultant Endocrinologist, Newcastle University, was an attempt to assess whether targeting a slightly higher TSH reference range in the elderly (over 80 years) is possible and to see if it would lead to any adverse effects on symptoms and quality of life (See BTF News 88).

Results so far have shown that a slightly lower dose of levothyroxine did not lead to any detrimental effect on symptoms or quality of life over a six month period..

Dr Salman Razvi and Professor Marian Ludgate, Professor of Molecular Endocrinology, Cardiff University are the joint winners of the 2017 BTF Research Award. They are aiming to study the underlying mechanism of the increase of blood TSH levels with age, which could lead to more age-appropriate TSH reference ranges in the future.

Two other recent studies have indicated that older people with mild hypothyroidism may not be at a disadvantage or do not benefit from treatment with levothyroxine. The Newcastle 85+ study (a large study of the elderly (85 years and over) in the North East has indicated that a slightly high blood TSH level – the blood test used to diagnose hypothyroidism – is not associated with worse outcomes.

A further study led by Professor David Stott of Glasgow University of hundreds of older adults across Europe with mild hypothyroidism has shown that this group does not benefit from being treated with levothyroxine in respect of improving symptoms or quality of life.

Summary

Diagnosis and treatment of thyroid disorders in older people is not always easy. Symptoms are not necessarily as obvious and other factors (such as symptoms of other diseases present along with thyroid disorders and interactions with other drugs) further complicate matters.

Older patients with thyroid disorders should be offered gradual and careful treatment, and, as always, require lifelong follow-up.

References

American Thyroid Association www.thyroid.org/thyroid-disease-older-patient/

Thyroid disease in Late Life, Leslie M.C. Goldenberg www.thyroid.ca/e4g.php

Study of Optimal Replacement of thyroxine in the elderly (SORTED) – results from the feasibility randomised controlled trial
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5057427/

Thyroid Hormone therapy for older adults with subclinical hypothyroidism, David J Stott
www.nejm.org/doi/full/10.1056/NEJMoa1603825

Hypothyroidism in the Elderly, Matthew I Kim, M.D.
Division of Endocrinology, Diabetes, and Hypertension, Brigham and Women’s Hospital, HIM-651, 77 Avenue Louis Pasteur, Boston, MA 02115
Last Update: March 15, 2017.
www.ncbi.nlm.nih.gov/books/NBK279005/