Examination for thyroid diseases

Indicators of thyroid dysfunction

Thyroid hormone feedback

TSH in serum

  • Its concentration is inversely proportional to the concentration of [[T4]] ,
    • assuming normal function of the hypothalamic-pituitary axis reflects the level of T 4 ,
  • Significantly increased: primary hypothyroidism,
  • Sometimes produced modified - you can also find
  • The method of first choice in case of suspected primary hypothyroidism or hyperthyroidism,
  • Monitoring of T4 substitution therapy ,
  • Is investigated in hypercholesterolemia and hyperprolactinemia.

Function test with TRH

  • Reflects TSH secretion
  • in central hypothyroidism, in TSH-producing tumors.

Total thyroxine (TT4) and free (FT4) in serum

  • Current secretion indicators
  • FT4 indicates the availability of the hormone by tissues
  • Thyroxine
    free thyroxin index – FTI
  • Prior to the treatment of hyperthyroidism, TSH secretion may still be suppressed in the long term.

Triiodothyronine total (TT3) and free (FT3) in serum

  • Triiodothyronine
    High levels of T3 autonomic hyperactivity of the gland
  • Indications - examination of hyperthyroidism, severity of primary hypothyroidism, differential diagnosis of low TSH levels.


Reverse T3 (RT3)

  • Indirect indicator of T4 to T3 conversion,
  • Examination of unknown causes of low TT3 or TT4.

Serum Thyroglobulin (TG)

  • Indicator of TG release from the active, inflammatory or tumor gland,
  • Follow-up of patients after thyroidectomy for differentiated ca as a tumor marker - diagnosis of relapse (increasing TG).

α-subunit of hCG

  • In general, it detects the formation of molecules with this subunit - even TSH.

Calcitonin, serum thyrocalcitonin

  • Thyroid gland C-cell secretory activity indicator ,
  • In the diagnosis of medullary tumors.

Disorders of thyroid hormone transport

Serum thyroxine binding globulin (TBG)

  • Quantitatively the most important carrier,
  • High values: genetically, in pregnancy, contraception,
  • Low concentrations: malnutrition, malabsorption, hepatic synthesis disorders,
  • We examine at T3 and T4 values ​​that do not correlate with the clinical condition.

Prealbumin, transthyretin in serum

  • The second most important carrier.

Binding capacity of transport proteins, T-uptake

  • Significance and indications as for TBG, saturate the serum sample with a known concentration of T3 and determine the unbound fraction.

Indicators of autoimmune diseases of the thyroid gland

Thyroperoxidase Antibodies (Thyreoperoxidase Antibodies, TPOAb)

  • Formerly described as antimicrosomal,
  • Reveal the presence of an autoimmune process, the possible risk of dysfunction,
  • Indications: goiter of unknown etiology, differential diagnosis of hyperthyroidism,
  • Postpartum risk screening.

Anti-thyroglobulin antibodies

  • They reveal the autoimmune process, they can explain incorrect results of TGB determination,
  • Monitoring of differentiated thyroid carcinomas.

Antibodies to TSH receptors

  • They can either stimulate or inhibit,
  • Risk of developing Graves' disease, risk of endocrine ophthalmopathy,
  • Differential diagnosis of hyperthyroidism.



References

  • SCHNEIDERKA, Petr, et al. Chapters from clinical biochemistry. 2nd edition. Prague: Karolinum, 2004. ISBN 80-246-0678-X.


Source

ws:Vyšetření u chorob štítné žlázy