I. Serum thyroxine measurement
1, serum free thyroxine (FT4) and free triiodothyronine (FT3) FT3, FT4, is the active part of circulating blood thyroid hormone, it is not affected by changes in blood TBG, and directly responds to the functional state of the thyroid gland. In recent years has been widely used in clinical, its sensitivity and specificity are significantly more than total T3 (TT3), total T4 ((TT4), normal value FT4 9-25pmol/L; FT33-9pmol/L (RIA), there are differences between laboratories.
2, serum thyroxine (TT4), is the most basic screening indicators to determine thyroid function, more than 99.95% of serum T4 and protein binding, of which 80%-90% and globulin binding called thyroxine-binding globulin (referred to as TBG), TT4 is the total amount of T4 five and protein binding, subject to TBG and other changes in the amount of binding protein and binding power Influence; TBG and by pregnancy, estrogen, viral hepatitis and other factors and rise, by androgens, hypoproteinemia (severe liver disease, nephrotic syndrome), prednisone and other effects and decline. Analysis is necessary to note.
3, serum total triiodothyronine (TT3) serum T3 and protein binding up to 99.5.% or more, also affected by TBG, TT3 concentration changes are often parallel to changes in TT4, but the early stages of hyperthyroidism hyperthyroidism relapse, TT3 often rises quickly, about 4 times the normal, TT4 rise more slowly, only 2.5 times the normal, so the measurement of TT3 for the diagnosis of the disease more sensitive indicators; For the initial onset of the disease, the treatment process, the observation of the efficacy and treatment of relapse after the aura, more regarded as sensitive, especially the diagnosis of T3 hyperthyroidism to get specific indicators, analysis and diagnosis should pay attention to the elderly indifferent type hyperthyroidism or long-standing disease TT3 may also not be high.
4, serum anti-T3 (revrseT3, rT3) rT3 is not biologically active, it is the degradation product of T4 in peripheral tissues, its change in blood concentration maintains a certain ratio with T4 and T3, especially consistent with the change of T4, it can also be used as an indicator to understand thyroid function, some of the early stage of this disease or early relapse only have rT3 elevation and as a more sensitive indicator. In severe malnutrition or certain systemic disease states rT3 is significantly elevated, while TT3 is significantly reduced, which is an important indicator for the diagnosis of low T3 syndrome.
II. TSH immunoradiometric analysis
(sTSH IRMA) The level of sTSH in normal blood circulation is 0.4-3.0 or 0.6-4.0μIU/ml. sTSH can be detected at the low limit of normal level by IRMA technique, and the minimum detection value of this method is generally 0.03/μIU/ml, which has high sensitivity, so it is also called sTSH ( It is also known as sTSH (“sensitive” TSH). It is widely used in the diagnosis and treatment monitoring of hyperthyroidism and hypothyroidism.
Thyroid hormone releasing hormone (TRH) excitation test
If TSH is elevated after intravenous injection of TRH 200μG, the disease can be ruled out; if TSH is not elevated, (no response), the diagnosis of hyperthyroidism is supported. It should be noted that TSH is not increased also in Graves’ ophthalmopathy with normal thyroid function, pituitary disease with insufficient TSH secretion, etc. This test has few side effects and is safer than the T3 suppression test for people with coronary heart disease or hyperthyroid heart disease.
IV. Thyroid uptake rate of 131I
This method has a 90% compliance rate for the diagnosis of hyperthyroidism. Iodine-deficient goiter may also be elevated, but there is generally no forward shift of the peak, and it can be used to differentiate T3 suppression test.
It should be noted that this method is affected by a variety of foods and iodine-containing drugs (including herbal medicines), such as antithyroid contraceptives, which increase the rate, so such drugs should be discontinued for more than 1-2 months before the evaluation.
Normal values: 3 and 24h values are 5%-25% and 20%-45% respectively, with a peak at 24h, as determined by the Geiger counting tube. In hyperthyroidism: 3h>25%, 24h>45%: and the peak is shifted forward.
V. Triiodothyronine suppression test
Abbreviated as T3 suppression test. It is used to identify goiter with increased 131I uptake rate due to hyperthyroidism or simple goiter.
Method: After measuring the basal 131I uptake rate, T320μg was administered orally 3 times daily for 6d (or 60mg of dry thyroid tablets were administered orally 3 times daily for 8d, and then in the 131I uptake rate. Compare the secondary results, normal people and patients with simple goiter swelling 131I rate decreased by more than 50, hyperthyroid patients can not be suppressed so the rate of 131I intake decreased under less than 50%, this method is prohibited for people with coronary heart disease or hyperthyroid heart disease, so as not to induce arrhythmia or angina pectoris.
Determination of thyroid stimulating antibody (TSAb)
The detection rate of positive TSAb in the blood of GD patients can be more than 80%-95%, which is not only of early diagnostic significance for the disease, but also valuable in determining the activity of the disease and whether it is relapsing, and can be used as an important indicator for treatment discontinuation.
VII. Diagnosis.
Typical cases can be diagnosed by detailed medical history and clinical manifestations, early mild cases, children with atypical hyperthyroidism in old age, often must be supplemented by necessary thyroid function tests to confirm, serum FT3, FT4, (TT3, TT4, increased in line with hyperthyroidism, only FT3 or TT3 increased and FT4, TT4, normal can be considered as T3 hyperthyroidism, only FT4 or TT4 increased and Those with normal FT3 and TT3 are T4 hyperthyroidism, and those with suspicious results can further undergo sTSH measurement and (or) TRH excitation test.
VIII. Etiological diagnosis.
Based on the diagnosis of hyperthyroidism, other causes of hyperthyroidism should be eliminated, combined with the patient’s ocular signs, diffuse goiter and other features, and if necessary, serum TSAb test, etc., can be shocked as GD, and nodules must be distinguished from autonomic high-functioning thyroid nodules, or multinodular goiter with hyperthyroidism;
In the latter case, there is usually no proptosis, the symptoms of hyperthyroidism are mild, the thyroid scan is a hot nodule, the function of the thyroid tissue outside the nodule is suppressed, the thyroid uptake rate of 131I is reduced in subacute thyroiditis with hyperthyroidism, the microsomal antibody level in the blood is increased in Hashimoto’s thyroiditis with hyperthyroidism, iodothyroidism has a history of iodine intake, the thyroid uptake rate of 131I is reduced, sometimes with elevated T4 and rT3, but not T3. Other conditions such as rare ectopic hyperthyroidism, TSH hyperthyroidism and tumor associated hyperthyroidism should be considered and ruled out one by one.
Differential diagnosis
(a) Simple goiter: no symptoms of hyperthyroidism; thyroid uptake rate of 131I may be increased, but the peak is not forward, T suppression test may be suppressed, T3 and T4 are normal or T3 is high, TSH (or sTSH) and TRH excitation test are normal.
(ii) Neurosis: There may be similar psychoneurotic syndrome without hyperthyroidism hypermetabolic syndrome, goiter and proptosis. If thyroid function tests are performed, the results are normal.
(c) Other: the main manifestations of wasting and hypothermia should be distinguished from tuberculosis and cancer; diarrhea should be distinguished from chronic colitis; arrhythmia should be distinguished from rheumatic heart disease and coronary artery atherosclerotic heart disease; unilateral proptosis should be distinguished from intraorbital tumor.