Clinical examination of the thyroid

Hugo R K Lisbôa, MD, Ph.D.

Medical College

University of Passo Fundo - RS

BRAZIL

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

Lesions recognizable through physical examination

Classification of Nontoxic GoiterNontoxic diffuse goiter

Endemic (iodine deficiency, goitrogens).Sporadic {congenital defects, chemical (lithium)}Compensatory (following partial thyroidectomy)

Nontoxic nodular goiterUni or multinodularFunctional and non functional

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

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

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

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.

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

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

Classical Clinical Examination

The following information could be obtainedvolume consistencymobility of the thyroid glandsurfacetemperaturefremitsensibility

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

ANATOMIC BONDARIES OF ANATOMIC BONDARIES OF THYROIDTHYROID

• Cricoid cartilage

• Supraesternal notch• Carotid arteries

Four anatomic points must be identifiedbefore palpation of thyroid gland is performed

ANATOMIC RELATIONSHIPS OF THE THYROID

ANATOMIC RELATIONSHIPS OF THE THYROID

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

Simplified Goiter Classification

• Degree 0 No goiter

• Degree 1 Goiter palpable but not visible

• Degree 2 Goiter palpable and visible

Clinical examination of the thyroid

Does clinical examination givesan accurate estimation of the thyroid gland ?

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 oldPalpation overestimated in 24 occasions

underestimated in 7 occasionsUltrasonography was suggested as an essential method for the evaluation of the thyroid in children

Ultrasonography of thyroid intra and inter observer variation

Two experts examined 152 thyroid lobes measuringsolid nodules and they agreed in 45 %Inter observer variation - kappa = 0,55 e 0,6 (2)

Two experts and two young physiciansexamined twice 53 adults and they agreed in 30% of the the casesIntra observer variation kappa= -0,04 and 0,54Inter observer variation kappa= 0,44 e 1,0 (1)

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)

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.

Relationship to other physical characteristics in children

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%.

Delange et al, studied 7599 European schoolchildren recommended that thyroid volume measured byultrasound should be considered dependent of age, sexand body surface area in non iodine deficient areas in that continent

Accuracy of clinical examination in the diagnosis of goiter

Thyroid volume in children according to the age

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.

Thyroid volume relationship to other characteristics in adults

Riehl J et al, found, among adults in a deficient iodineintake area, that the thyroid volume was dependentof the age. Individuals with less than 21 years 13,3mlIndividuals with more than 70 years 29,9 ml

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 largegoiters (35,9+-24ml) .

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 hada consistency similar to the thyroid cartilage.

What a painful thyroid means?

• Subacute thyroiditis

• Hemorrhage into a nodule

• Cancer (rare)

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

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

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

Usefulness of clinical examination of the thyroid

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