The single most reliable test to diagnose all common forms of both hypothyroidism and hyperthyroidism is measurement of serum thyroid stimulating hormone (TSH). While there is some variation over what is considered to be a ‘normal’ range, the American Association of Clinical Endocrinologists considers that individuals outside the range of 0.30–3.04 mIU/L TSH should be considered for treatment.2,3
In patients with primary hypothyroidism, elevated TSH levels are observed among patients with mild or secondary (pituitary or hypothalamic) hypothyroidism, serum TSH levels may be low, normal, or mildly elevated, and so serum T4 concentration should be measured in addition to the serum TSH concentration.
In patients with hyperthyroidism, suppressed TSH levels are observed to diagnose hyperthyroidism accurately, test methodologies with a sensitivity to detect TSH at 0.02 mIU/L or less are recommended. Where assays are not accurate enough, a serum T4 assay and a total or free T3 assay should be employed in addition to measurement of the serum TSH concentration.
As physical examination on its own does not always help in diagnosing thyroid disorders, a number of questionnaires have been developed among non-HIV-infected people to aid diagnosis and assess symptoms and/or monitor progress.4 Such tools include the following:
(available from authors) was developed based on 104 items, grouped into four domains: physical; energy and wellbeing; mood/emotions; and cognitive functioning. The questionnaire requires the assistance of an interviewer to complete and following assessment, an impact score is calculated according to the scores provided for each component, and the importance the patient attributes to them. The questionnaire has been validated in patients with subclinical hypothyroidism.6 The authors found that symptoms in subclinical patients were similar to those with overt hypothyroidism although not as frequent.
is a disease-specific questionnaire based on another tool initially designed for patients with diabetes - the Audit of Diabetes-Dependent Quality of Life (ADDQoL).8 The thyroid questionnaire uses 18 items that are perceived by thyroid disease patients as being particularly relevant to their QoL including: social life, work, marriage and relationships, sex-life, household tasks and holidays. A total score is calculated to assess the overall weighted impact of the disease on QoL. The ThyDQoL has been validated in 110 hypothyroid patients and has been shown to have excellent internal consistency and reliability.9
(available from authors) assesses persisting symptoms in people with hypothyroidism on treatment with L-thyroxine. The TSQ has 12 questions based on the same format as the General Health Questionnaire (GHQ-12). Using this questionnaire it was demonstrated that hypothyroid patients, even with adequate L-thyroxine replacement therapy, have significant psychological impairment and hypothyroid symptoms when compared to euthyroid controls.
was a diagnostic index designed over 40 years ago that scored the presence or absence of 21 signs and symptoms of hypothyroidism in order to establish a diagnosis. Since the advent of TSH testing, this scoring system is no longer useful in diagnosing patients with hypothyroidism, but retains some functionality for assessing signs and symptoms of the disease.
is based on the Billewicz index, but incorporates thyroid hormone testing and parameters known to reflect tissue manifestations of hypothyroidism, such as ankle reflex relaxation time and total cholesterol. The index may be useful in helping to evaluate overt hypothyroidism clinically, but is less helpful in the context of subclinical disease.