ABSTRACT
BACKGROUND: The availability of sensitive and specific assays for evaluation of the thyroid axis has allowed definition of thyroid disorders at subclinical stage. This has almost obviated the use of thyrothrophin releasing hormone (TRH) study. We describe here a group of patients with minimal signs of hypothyroidism having normal thyroid function tests (T3, T4, thyroid stimulating hormone (TSH)) and have shown exaggerated TSH response to TRH. MATERIAL AND METHODS: Total 82 subjects were studied. Of these, 11 were age and sex matched controls, and 71 were patients. In all subjects TSH and other thyroid assays (T3, T4, FT4) were done by immunoradiometric assay (IRMA), and radioimmunoassay (RIA) respectively. Thyroid antibody was carried out by haemagglutination method. Results were compared to age and sex related normal ranges. To further investigate the status of thyroid axis, TRH study was carried out using standard protocol. RESULTS: Based on TRH study patients were grouped in three categories. Group 1 included 29 patients whose TSH response to TRH was normal. Group 2 included 20 patients with normal baseline TSH and exaggerated TSH response to TRH and Group 3 included 18 patients with baseline TSH in the range of 5 to 10 mu IU/ml and exaggerated TSH response to TRH. There was a significant difference to total T3 between group 1 and 3 (p < 0.05) but mean values were within normal limits. While no significant difference was observed in total T4 between controls and patient's group. Serum TSH values were high in group 3 as compared to controls and Group 1 and 2 (p < 0.0001). For Free T4 no statistical significance was observed between Group 1, 2 and 3. Thyroid antibodies were positive in 22.7% of patients in Group 2 and 33.33% in Group 3. CONCLUSION: We conclude from the present study that even with sensitive TSH assays TRH study still has a role to mark the early stage of hypothyroidism. Those with a normal or upper normal TSH with exaggerated response to TRH are termed as sub-biochemical hypothyroidism and can be considered for thyroid replacement therapy.
Subject(s)
Adolescent , Adult , Aged , Child , Female , Humans , Hyperthyroidism/blood , Male , Middle Aged , Probability , Radioimmunoassay , Reference Values , Sensitivity and Specificity , Severity of Illness Index , Thyroid Function Tests , Thyrotropin/blood , Thyrotropin-Releasing Hormone/diagnosisABSTRACT
Fifteen IDDM patients were evaluated for thyroid hormone abnormalities before and after control of diabetes mellitus/ketoacidosis. Blood sugar mean +/- SEM mg/dl on admission was 430 +/- 20.3 and after therapy fasting and post prandial blood sugar values were 120 +/- 14.5 and 150 +/- 20.2 respectively. GHb mean +/- SEM % on admission was 15.2 +/- 0.36. Serum T3 mean +/- SEM ng/dl of 0.36 +/- 0.04 was in hypothyroid range and rT3 mean +/- SEM ng/ml 0.40 +/- 0.6 was significantly raised (P < 0.001) before therapy. After metabolic control both T3 and rT3 became normal. T4 concentration mean +/- SEM meg/dl of 5.5 +/- 0.7 was well within normal range before therapy and rose to mean +/- SEM mcg/dl 8.8 +/- 0.5 after therapy (P < 0.01). TSH response to TRH was blunted in uncontrolled state. It is concluded that peripheral changes in T3, T4 and rT3 (low T3, high rT3 and low or normal T4) occurred in uncontrolled diabetic state during ketoacidosis. TSH response to TRH was blunted due to suppression of hypothalamic pituitary thyroid axis which takes more than a week for complete recovery.
Subject(s)
Adolescent , Adult , Blood Glucose/metabolism , Diabetes Mellitus, Type 1/complications , Diabetic Ketoacidosis/metabolism , Female , Humans , Male , Middle Aged , Thyroid Gland/physiopathology , Thyroid Hormones/metabolism , Thyrotropin-Releasing Hormone/diagnosisABSTRACT
The mean basal serum TSH (IRMA) concentrations and their increments after exogenous TRH stimulation in euthyroid subjects and patients with borderline and definite hypo or hyperthyroidism were reported. In euthyroid subjects, the increment of serum TSH (IRMA) after TRH stimulation was higher in females than in males. The measurement of basal serum TSH (IRMA) alone could discriminate euthyroid subjects from patients with thyroid dysfunction. Significant correlation between basal serum TSH (IRMA) concentrations and their corresponding increment of serum TSH (IRMA) at 30 minute after TRH stimulation in the whole group of patients was observed. Therefore, the measurement of basal serum TSH (IRMA) concentration had sufficient discriminatory value in differentiating patients with or without thyroid dysfunction and obviating the need to perform TRH stimulation test.