The recognition of thyroid disorders in the Acute Medical Unit is not always easy as the symptoms and signs may be non-specific and easily mistaken for other illnesses. In the elderly, for example, the insidious nature of thyroid disorders may be mistaken for normal ageing. Thyroid conditions presenting in the Acute Medical Unit range from asymptomatic subclinical thyroid dysfunction to life-threatening severe hyperthyroidism (thyroid storm) or extreme hypothyroidism (myxoedema coma). We describe our experience in an Acute Medical Unit in a busy general hospital and refer to the published literature.
Thyroid dysfunction comprises both clinical and subclinical thyroid deficiency (hypothyroidism) and thyroid excess (hyperthyroidism). Subclinical thyroid dysfunction is defined as normal free thyroid hormones (fT4, fT3) but abnormal TSH values. About 15% of patients admitted to hospital will have subclinical thyroid dysfunction . Overall, about 2% of hospital in-patients in the UK will be newly diagnosed with hypothyroidism . By contrast 0.3 - 1% of in-patients will have previously undiagnosed hyperthyroidism, a rate similar to that seen in the community . In our hospital, all patients with medical conditions are admitted via the Acute Medical Unit (AMU). We were interested to examine the pattern of thyroid disorders presenting to our AMU and to assess the impact of the thyroid condition on their hospital stay.
We investigated all adult admissions via our AMU from January to December 2018 coded as having a primary or secondary diagnosis of thyroid disorder. We used the ICD-9 hospital codes for thyroid disorders (E000 - E079). Sixteen patients (13 females, 3 males) were identified. The clinical records of these patients were then examined to determine the clinical presentation of these patients, the nature of their thyroid disorder, the management of their condition and the impact on their hospital stay.
The clinical characteristics of the patients are shown in Table 1. The patients were predominantly female (13/16) and aged 27 - 94 years. Of the eight patients with hypothyroidism, five were subclinical. By contrast, only 3 of the eight hyperthyroid patients were classified as subclinical. In the elderly patients (defined as those over 75), thyroid excess was more common (2 subclinical, 3 overt hyperthyroidism) than thyroid deficiency (1 subclinical hypothyroidism). Atrial fibrillation occurred in both hyperthyroid and hypothyroid patients. The median duration of hospital stay was 1 day [range 1-62].
The results of this survey might suggest that thyroid disorders
do not commonly account for clinical presentations to this
hospital. However, this data is based on hospital coding which
relied upon the discharge diagnosis. Only if a thyroid disorder
was entered as a diagnosis in the discharge summary would the
patient have been identified. Prevalence data based on laboratory
results would almost certainly result in a much higher prevalence
of abnormal thyroid function. The low number of patients
identified might also reflect missed diagnoses. The presentation
of hyperthyroidism in the elderly is frequently less obvious than
in younger patients as older patients typically present with
apathy and weight loss rather than with hyperdynamic symptoms
such as tremor, heat intolerance and agitation . Elderly
patients with hyperthyroidism may present with agitation and
confusion although this presentation was not seen in this small
series. Similarly, patients with hypothyroidism may present to
their doctors with non-specific symptoms such as fatigue and
The majority of identified patients had a short stay on AMU
and were discharged on treatment to be followed in outpatient
clinics. This might suggest that the thyroid condition had little
clinical impact. However, we found 3 patients with rapid atrial
fibrillation associated with hyperthyroidism which, at least in
one patient, precipitated congestive heart failure. Thyroid storm
or severe hyperthyroidism is characterized by a hyper-metabolic
state, neuropsychiatric change and often cardiac failure . It
carries a high mortality especially in older patients.
We identified one patient in this cohort with severe hypothyroidism
requiring transfer to the High Dependency Unit. Often
referred to as ‘myxoedema coma’ (although neither oedema nor
coma may be present), the condition is more common in elderly
females and is associated with a high mortality rate . This
patient had a prolonged hospital stay requiring mechanical ventilation
and intravenous thyroxine. His recovery was complicated
by hospital acquired pneumonia and acute myocardial infarction.
Treatment of hypothyroidism with levothyroxine in older patients
or those with cardiac disease needs to be done cautiously as it can
provoke angina or cardiac rhythm disorders. Subclinical thyroid
dysfunction is common in hospitalized patients. Subclinical hyperthyroidism
is associated with atrial fibrillation and osteoporosis.
Current guidelines recommend treatment when the TSH is
fully suppressed (<0.1 mU/l) especially if over 65 years and cardiac
risk factors are present . Dose adjustment is needed if the
subclinical hyperthyroidism is due to excessive doses of levothyroxine.
Subclinical hypothyroidism (SCH) is often asymptomatic.
It is important to recognize and treat women with SCH who are
planning a pregnancy or who are pregnant as soon as possible as
levothyroxine may improve cognitive function in the offspring.
Treatment for SCH is recommended for non-pregnant adults if
the serum TSH exceeds 10 mU/l even if no symptoms . However,
treatment of SCH is not generally recommended in those
aged over 80 years. Testing thyroid function when patients are severely
ill can prove challenging because of physiological changes
that are thought to prevent excessive catabolism (‘euthyroid sick
syndrome’) . Patients typically have low circulating free thyroid
hormone levels and low TSH concentration which recover as
the illness resolves. This phenomenon may contribute to the high
prevalence of abnormal thyroid results observed in hospitalized
patients. For this reason, routine testing of thyroid function in patients
admitted acutely to hospital is not recommended .
With the widespread availability of thyroid hormone testing,
abnormalities of thyroid function are commonly observed especially when patients are tested in hospital settings. Results
need to be interpreted carefully in relation to the clinical situation.
Although uncommon, serious thyroid conditions which may
potentially be life-threatening may present to the acute physician
and a high index of suspicion is needed so that these disorders are
detected early. Patients with thyroid disorders may present with
non-specific or atypical symptoms especially in the elderly and in
these patients, meticulous clinical assessment is needed in order
to make the right diagnosis.