Hypothyroid symptoms fail to predict thyroid insufficiency in old people: A population-based case-control study

BACKGROUND: Clinic-based studies have indicated that older hypothyroid patients may present only few symptoms.

METHODS: In this population-based study of hypothyroidism, we investigated how the power of symptom presence predicts overt hypothyroidism in both young and older subjects. We identified patients newly diagnosed with overt autoimmune hypothyroidism in a population (n=140, median TSH (95%-CI): 54.5 (28.3-94.8), median total T4: 37 (18-52)), and individually matched each patient with four controls free of thyroid disease (n=560). Participants filled out questionnaires concerning presence and duration of symptoms. We compared the usefulness of hypothyroidism-associated symptoms in predicting overt hypothyroidism in different age groups (young: <50 years, middle age: 50-59 years, old: ≥ 60 years) also taking various confounders into account.

RESULTS: In young hypothyroid patients, all 13 hypothyroidism-associated symptoms studied were more prevalent than in their matched controls, whereas only three of those (tiredness, shortness of breath, and wheezing) were more prevalent in old patients. Mean number of symptoms presented at disease onset were 6.2/5.0/3.6 at the ages of 0-49/50-59/60+ years. In young vs. old people with 0-1 symptoms, the OR (95%-CI) for being hypothyroid was 0.04 (0.007-0.18) vs. 0.34 (0.15-0.78) (reference all other groups). In young vs. old subjects reporting ≥4 symptoms, OR for being hypothyroid was 16.4 (6.96-40.0) vs. 2.22 (1.001-4.90). ROC analyses revealed that the symptom score was an excellent tool for predicting hypothyroidism in young men (AUROC (95%-CI): 0.91 (0.82-0.998)) whereas it was poor in evaluating older women (AUROC: 0.64 (0.54-0.75)).

CONCLUSION: Hypothyroid symptom score is a good discriminating tool to identify hypothyroidism in young patients, but fail to identify hypothyroidism in elderly. Thus, thyroid function should be tested on wide indications in old age.