Clinical examination of the thyroid

1. Clinical examination of the thyroid Hugo R K Lisbôa, MD, Ph.D. Medical College University of Passo Fundo - RS BRAZIL

2. Objectives of this lecture • To evaluate the usefulness and limitations of the physical examination on the diagnosis of thyroid diseases according to concepts of clinical epidemiology

3. Lesions recognizable through physical examination • Classification of Nontoxic Goiter • Nontoxic diffuse goiter • Endemic (iodine deficiency, goitrogens). • Sporadic {congenital defects, chemical (lithium)} • Compensatory (following partial thyroidectomy) • Nontoxic nodular goiter • Uni or multinodular • Functional and non functional

4. Thyroid diseases • 50% of people in the community have microscopic nodules • 3.5% have occult papillary carcinoma, • 15% have palpable goiters • 10% demonstrate an abnormal thyroid-stimulating hormone level • 5% of women have overt hypothyroidism or hyperthyroidism

5. Prevalence of the most common thyroid diseases • Diffuse endemic goiter : Depends on iodine supply.(The term endemic goiter is used when thyroid enlargement is found in more than 10% of the population). • Nodular goiter: Up to 5% everywhere. Increases with age and iodine deficiency • Thyroid cancer: average annual incidence of all types of thyroid cancer was 37.0 cases/1,000,000 population

6. Incidence of Hypo and Hyperthyroidism (Whickham Cohort) • The mean incidence (with 95% confidence intervals) of spontaneous hypothyroidism in women was 3.5/1000 survivors/year (2.8-4.5) and in men was 0.6/1000 survivors/year (0.3-1.2). • The mean incidence of hyperthyroidism in women was 0.8/1000 survivors/year (0.5-1.4) and was negligible in men

7. History The clinical examination of the thyroid is a powerful tool for the diagnosis of the most comum thyroid disease The thyroid lies immediately under the skin it is easily reached by inspection and palpation.

8. Inspection • Tip the patients head back a bit • Use tangential lighting from the tip of the patients chin • Ask for swallowing • Observe the thyroid cartilage, cricoid cartilage and the thyroid gland raising with swallowing

9. Physical Examination • Do not press to much the thyroid • You can loose the sensitivity of your fingers • Try to not strangle your patient Oil on canvas. 1967 Tomie Othake, Brazilian Painter

10. Classical Clinical Examination • The following information could be obtained • volume • consistency • mobility of the thyroid gland • surface • temperature • fremit • sensibility

11. Palpation • Palpate the thyroid gland from behind • Localize anatomic boundaries • Thyroid isthmus is often palpable • Thyroid lobes are barely or not palpable • The concistense is rubbery, similar to that of sternomastoid muscle

12. ANATOMIC BONDARIES OF THYROID Four anatomic points must be identified before palpation of thyroid gland is performed • Cricoid cartilage • Supraesternal notch • Carotid arteries

13. ANATOMIC RELATIONSHIPS OF THE THYROID

14. ANATOMIC RELATIONSHIPS OF THE THYROID

15. Classical Goiter Classification • Ia -thyroid not visible, lateral lobes smaller than the distal phalanx of the thumb • Ib - thyroid visible with neck in extended position • II - thyroid visible with the neck in normal position • III - thyroid visible at distance

16. Simplified Goiter Classification • Degree 0 No goiter • Degree 1 Goiter palpable but not visible • Degree 2 Goiter palpable and visible

17. Clinical examination of the thyroid Does clinical examination gives an accurate estimation of the thyroid gland ?

18. Accuracy of clinical examination on diagnosis of goiter in children Skvor J, showed a discrepancy between palpation and ultrsonogrphy among 88 individual of 13 years old Palpation overestimated in 24 occasions underestimated in 7 occasions Ultrasonography was suggested as an essential method for the evaluation of the thyroid in children

19. Ultrasonography of thyroid intra and inter observer variation Two experts and two young physicians examined twice 53 adults and they agreed in 30% of the the cases Intra observer variation kappa= -0,04 and 0,54 Inter observer variation kappa= 0,44 e 1,0(1) Two experts examined 152 thyroid lobes measuring solid nodules and they agreed in 45 % Inter observer variation - kappa = 0,55 e 0,6 (2)

20. Relationship to other physical characteristics in children Ueda D, examined 300 healthy children and found a positive correlation among thyroid volume and weight and height. (1). Takalo RM et al, found a positive correlation in young individual of 13 years among thyroid volume measured by ultrasound and the weight and body surface area(2)

21. Relationship to other physical characteristics in children The thyroid volume was found to have a positive correlation with body surface area, age and skinfold but in a multiple regression analysis only body surface area remained associated with thyroid volume. The upper limit (95th percentile) of the ratio of thyroid volume to body surface area (ECOBODY Index) was 6.2 ml/m2.

22. Accuracy of clinical examination in the diagnosis of goiter Considering this index as the criterion standard, the estimated performance of clinical examination for the detection of goiter in the 1094 schoolchildren was: sensitivity of 41%, specificity of 91%, positive predictive value of 27% negative predictive value of 95%.

23. Accuracy of clinical examination in the diagnosis of goiter Delange et al, studied 7599 European schoolchildren recommended that thyroid volume measured by ultrasound should be considered dependent of age, sex and body surface area in non iodine deficient areas in that continent

24. Thyroid volume in children according to the age

25. Which characteristics should the thyroid be related • In areas with malnutrition, such as Bangladesh, the BSA reference should be preferred to the reference based on age. • Results from the US children indicated that a thyroid volume reference based on weight alone would perform as well as the one based on BSA. • European schoolchildren had larger thyroids than US children, perhaps due to a residual effect of iodine deficiency in the recent past in some areas in Europe.

26. Thyroid volume relationship to other characteristics in adults Riehl J et al, found, among adults in a deficient iodine intake area, that the thyroid volume was dependent of the age. Individuals with less than 21 years 13,3ml Individuals with more than 70 years 29,9 ml

27. Accuracy of clinical examination in the diagnosis of goiter in adults A good correlation was found between clinical examination and ultrasonography (r2=0,872) in large goiters (35,9+-24ml) .

28. What a hard thyroid means? • If painful - Subacute thyroiditis • If not painful- Hashimoto’s thyroidites, cancer or Riedel’s thyroidites (rare) Thyroid gland is considered to be hard if it had a consistency similar to the thyroid cartilage.

29. What a painful thyroid means? • Subacute thyroiditis • Hemorrhage into a nodule • Cancer (rare)

30. Summary • Clinical examination is not accurate in the diagnosis of small goiters • The thyroid volume is related to age and body surface area in in children • The upper limit of normal range for children suggested is 6,2ml/m2

31. Usefulness of clinical examination of the thyroid In the diagnosis of goiter in areas of mild to severe iodine deficiency where the thyroid glands are bigger In the identification of normal thyroid due to its good predictive negative value

32. Useful Links • American Thyroid Association • http://www.thyroid.org/ • Endocrine Society • http://www.endo-society.org • Asia and Oceania Thyroid Association • http://www-dnm.kuhp.kyoto-u.ac.jp/AOTA/1cir-e.html • European Thyroid Association • http://www.uwcm.ac.uk/uwcm/md/ETA.html • Latin American Thyroid Society • http://www.lats.org