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Thyroid Disease – Diagnostic Tools

Diagnostic Tools

Blood tests1

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.


Questionnaires

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:

The Chronic Thyroid Questionnaire (CTQ)5

(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.



The Underactive-Thyroid-Dependent Quality of Life Questionnaire (ThyDQoL)7

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

The Thyroid Symptom Questionnaire (TSQ)10

(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.

The Billewicz index11

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.

The Zulewski Index12

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.






References

  1. Spencer CA, Takeuchi M, Kazarosyan M. Current status and performance goals for serum thyrotropin (TSH) assays. Clin Chem. 1996;42:140–145. 
  2. American Association of Clinical Endocrinologists Medical Guidelines for Clinical Practice for the Evaluation and Treatment of Hyperthyroidism and Hypothyroidism. 08 June 2011.  
  3. American Association of Clinical Endocrinologists: 2003 Campaign Encourages Awareness of Mild Thyroid Failure, Importance of Routine Testing. Accessed 08 Jun 2011.   
  4. Indra R, Patil SS, Joshi R, Pai M, Kalantri SP. Accuracy of physical examination in the diagnosis of hypothyroidism: a cross-sectional, double blind study. J Postgrad Med. 2004;50(1):7–11.
  5. Jaeschke R, Guyatt G, Cook D, Harper S, Gerstein HC. Spectrum of quality of life impairment in hypothyroidism. Qual Life Res. 1994;3(5):323–327.
  6. Jaeschke R, Guyatt G, Gerstein H, et al. Does treatment with L-thyroxine influence health status in middle-aged and older adults with subclinical hypothyroidism? Gen Intern Med. 1996;11(12):744–749. 
  7. McMillan CV, Bradley C, Woodcock A, Razvi S, Weaver JU. Design of new questionnaires to measure quality of life and treatment satisfaction in hypothyroidism. Thyroid. 2004;14:916–925. 
  8. Bradley C, Todd C, Gorton T, Symonds E, Martin A, Plowright R. The development of an individualized questionnaire measure of perceived impact of diabetes on quality of life: the ADDQoL. Qual Life Res. 1999;8(1–2):79–91. 
  9. McMillan CV, Bradley C, Razvi S, Weaver JU. Psychometric validation of new measures of hypothyroid-dependent quality of life (QoL) and symptoms. Endocrine Abstracts. 2005;9:151. 
  10. Saravanan P, Chau WF, Roberts N, Vedhara K, Greenwood R, Dayan, CM. Psychological well-being in patients on ‘adequate’ doses of L-thyroxine: results of a large, controlled community-based questionnaire study. Clin Endocrinol. (Oxf) 200;57(5):577–585. 
  11. Billewicz WZ, Chapman RS, Crooks J, et al. Statistical methods applied to the diagnosis of hypothyroidism. Q J Med. 1969;38(150):255–266.
  12. Zulewski H, Muller B, Exer P, Miserez AR, Staub JJ. Estimation of tissue hypothyroidism by a new clinical score: evaluation of patients with various grades of hypothyroidism and controls. J Clin Endocrinol Metab. 1997;82(3):771–776.