Diagnostics of thyroid diseases

Clinical picture: hypothyroidism and hyperthyroidism

Diagnostic workup begins with assessing the patient's clinical status, which most commonly fits into one of two syndromes:

• Nervous system and development: with hormone deficiency (hypothyroidism), inhibition prevails — lethargy, weakness, psychomotor and growth retardation. With excess (hyperthyroidism), excitation, nervousness, and rapid fatigue are observed, while psychomotor development is not impaired, and growth may be accelerated.
• Trophic changes: hypothyroidism is characterized by weight gain (due to edema syndrome), dry skin, and hair loss (alopecia). In thyrotoxicosis, patients lose weight, and their skin feels hot, although overall body temperature remains normal.
• Cardiovascular system: decreased function causes bradycardia, increased function causes tachycardia and a subjective sensation of palpitations even at rest.
• Gastrointestinal tract: hypothyroidism decreases motility (constipation), while hyperthyroidism accelerates transit (stool softening).
• Ophthalmological status: specific "eye" symptoms (e.g., exophthalmos) are pathognomonic exclusively for hyperthyroidism.

Physical examination and goiter classification

During neck palpation, the physician must assess three parameters: size (degree of enlargement), consistency (soft-elastic, doughy, or firm), and the presence of focal pathology (nodules).

To standardize sizes, the WHO classification (2001) is used, based on comparing the volume of each lobe with the size of the distal (terminal) phalanx of the patient's own thumb:

1. Grade 0 (normal): no goiter, the lobe is no larger than the phalanx.
2. Grade 1 (palpable goiter): the gland is not visible in the physiological position of the neck, but the size of the lobes exceeds the phalanx. Any palpable nodules are also automatically assigned to this grade, even if the total volume of the organ is not increased.
3. Grade 2 (visible goiter): enlargement of the gland is clearly visualized without the need for palpation.

Laboratory and instrumental diagnostics

Function assessment is based on the negative feedback axis: TSH and free T4 levels. Determination of free T3 is not routine and is prescribed only in case of discordant (inconsistent) values of baseline hormones (e.g., when diffuse toxic goiter is suspected).

When indurations or characteristic ultrasound signs are detected, immunological screening is indicated: antibodies to thyroid peroxidase (TPOAb) and thyroglobulin (TgAb). A specific marker for diffuse toxic goiter is antibodies to the TSH receptor (TRAb).

Ultrasound examination (ultrasound) is used to assess volume, search for nodules, and identify specific echo-signs of autoimmune inflammation (heterogeneity, "fibrous strands" of the parenchyma). Important rule: if the hormonal background is normal (eutin state), then isolated reduction in gland size or its asymmetry is not considered pathology.

To clarify the cellular composition of nodular formations, fine-needle aspiration biopsy (FNAB) is performed. Additionally, scintigraphy, CT, MRI, barium swallow radiography (to assess compression of neck organs), as well as ECG and echocardiography may be prescribed to monitor the systemic impact of the pathology.

Class and exam questions

What else to study on this topic

• Cytological interpretation of fine-needle aspiration biopsy (FNAB) results
• Indications for radioisotope study (scintigraphy) of the thyroid gland
• Assessment of compression syndrome: barium swallow radiography, CT, and MRI
• Specific ECG and echocardiography changes in thyrotoxicosis and hypothyroidism
• Pathogenesis of edema syndrome and hypercholesterolemia formation in thyroid hormone deficiency

Other topics in the section «Chapter 11. Endocrine Diseases in Children»

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.