Delta Thyroid-stimulating Hormone Research Articles

Lack of correlation between cerebrospinal fluid thyrotropin-releasing hormone (TRH) and TRH-stimulated thyroid-stimulating hormone in patients with depression

Background: It has been proposed that elevated central thyrotropin-releasing hormone (TRH) is associated with the blunted thyroid-stimulating hormone (TSH) response to TRH in patients with depression. Few studies have directly evaluated this relationship between central nervous system and peripheral endocrine systems in the same patient population.Methods: 15 depressed patients (4 male, 11 female, 12 bipolar, and 3 unipolar) during a double-blind, medication-free period of at least 2 weeks duration, underwent a baseline lumbar puncture followed by a TRH stimulation test. Cerebrospinal fluid (CSF) TRH and serial serum TSH, free thyroxine, triiodothyronine, prolactin, and cortisol were measured. A blunted response to TRH was defined as a delta TSH less than 7 μU/mL.Results: There was no significant difference in mean CSF TRH between “blunters” (2.82 ± 1.36 pg/mL) and “nonblunters” (3.97 ± 0.62 pg/mL, p = .40). There was no evidence of an inverse relationship between CSF TRH and baseline or delta TSH. There was no correlation between CSF TRH and the severity of depression or any other endocrine measure.Conclusions: These data are not consistent with the prediction of hypothalamic TRH hypersecretion and subsequent pituitary down-regulation in depression; however, CSF TRH may be from a nonparaventricular nucleus–hypothalamic source (i.e., limbic area, suprachiasmatic nucleus, brain stem–dorsal raphe) and thus, not necessarily related to peripheral neuroendocrine indices.

THE THYROTROPIN RELEASING HORMONE STIMULATION TEST IN ALCOHOLISM

The mechanism for a blunted thyroid stimulating hormone (TSH) response to thyrotropin releasing hormone (TRH) in alcoholics is not known. We performed a combined TRH and gonadoliberin stimulation test on three well-defined groups of nondepressed alcoholic men. Group A comprised patients with acute withdrawal symptoms (n = 28), group B patients abstinent for 5-8 weeks (n = 29) and group C patients who had been abstinent for > 2 years (n = 16). Twenty-two healthy male volunteers were used for comparison. A blunted TSH response to TRH (delta TSH < 5 microU/l) occurred only in groups A (39%) and B (17%). In group A delta TSH showed a significant negative correlation with the severity of withdrawal symptoms and a significant positive correlation with serum magnesium levels. In group B, patients with a family history of alcoholism had significantly lower delta TSH levels than those without such a family history. Groups did not differ with respect to basal and delta prolactin, and TSH responses were not significantly associated with vitamin deficiency, cortisol levels or free thyroid hormone levels. We conclude that TRH stimulation test blunting appears to be related to factors operating in the withdrawal state and improves with continued abstinence. A possible role of genetic factors and serum magnesium needs to be further explored.

Assessment of interchangeability of two brands of levothyroxine preparations with a third-generation TSH assay

To evaluate, in a prospective fashion, the clinical interchangeability between two brands of levothyroxine, Synthroid (Boots Pharmaceuticals, Inc., Lincolnshire, Illinois) and Levoxine (Daniels Pharmaceuticals, Inc., St. Petersburg, Florida), by using clinical scores of hyperthyroidism and hypothyroidism, free thyroxine index (FTI), sensitive thyroid-stimulating hormone (TSH), and thyrotropin-releasing hormone (TRH) stimulation testing. Twenty-three of the 31 patients with long-standing primary hypothyroidism (6 men, 25 women; age range 30 to 71 years, mean 47.2 +/- 2.2 SEM) were switched from Synthroid to Levoxine (group 1) and the remaining patients from Levoxine to Synthroid (group 2). After switching, each patient continued to receive the same dosage as previously. Clinical scores of hypothyroidism and hyperthyroidism (Billewicz and Crooks scoring systems, respectively), basal FTI, and TRH stimulation test were obtained before and 4 months after the switching. Comparison of the variables before and after switching was performed separately in each subgroup and in the entire group. There was no statistically significant difference in the hypothyroid clinical scores (-40.1 +/- 1.2 versus -39.7 +/- 1.2), the hyperthyroid clinical scores (-19.6 +/- 0.9 versus -19.2 +/- 1.0), FTI (9.6 +/- 0.3 versus 9.6 +/- 0.3), basal TSH levels (1.4 +/- 0.2 versus 1.4 +/- 0.2 mIU/L), or the magnitude of TSH response to TRH (mean delta TSH 9.4 +/- 1.5 versus 9.2 +/- 1.4 mIU/L), whether the patients were receiving Synthroid or Levoxine. Switching did not result in substantial clinical or laboratory changes in any individual patient. We conclude that the two brands of levothyroxine are clinically interchangeable.

Thyroid Function and Release of Thyroid-stimulating Hormone and Prolactin from the Pituitary in Human Obesity

Thyroid function, basal serum thyroid-stimulating hormone (TSH) and prolactin concentrations, and the effects of 200 micrograms TSH-releasing hormone (TRH) given intravenously on TSH (delta TSH) and prolactin (delta prolactin) were investigated in 25 euthyroid obese subjects and 20 lean controls. No significant differences in serum thyroid hormone concentrations, glucose metabolism parameters, or basal TSH and prolactin concentrations were detected between groups, but a significant (P less than 0.01) increase in delta TSH and a significant (P less than 0.01) decrease in delta prolactin were observed in obese subjects. No significant differences in basal TSH and prolactin were observed in obese men and women compared with corresponding lean controls, but delta prolactin decreased significantly (P less than 0.01) in obese men and women compared with lean controls and TSH increased significantly (P less than 0.01) in obese men and women. No correlation was found between delta TSH or delta prolactin and body mass index. The study suggests that hyper-responsiveness of TSH and hyporesponsiveness of prolactin to TRH in obese subjects can be related to changes in the central serotoninergic system.

TRH Test Identification of Thyroid-Responsive Depression

AbstractIn a series of 39 patients with major depression, 16 were found to have delta thyroid-stimulating hormone (TSH) results greater than 20, suggestive of subclinical hypothyroidism. The two groups of patients did not differ in severity of depression (Beck Depression Inventory), in subclinical symptoms of mood disorder (the General Behavior Inventory), in family history of depression, or in family history of thyroid disorder. Thyroid hormone treatment alone was given to 8 of these 16, all of whom had full remissions (p = 0.004). Six-month follow-up data indicated that these remissions were maintained, while thyroid function measures were significantly improved. Depressed patients who have thyroid insufficiency as determined by delta TSH results may respond to treatment with thyroid hormone, without need for antidepressants.

TRH stimulation test and depression

A thyrotropin-releasing hormone (TRH) stimulation test was performed in 52 male inpatients with major depressive disorder. Twenty-nine percent of the 52 subjects had a delta thyroid-stimulating hormone (ΔTSH) < 5 μU/ml. The cerebrospinal fluid (CSF) amine metabolites, 3-methoxy-4-hydroxyphenylglycol (MHPG), homovanillic acid (HVA), and 5-hydroxyindoleacetic acid (5HIAA), were measured in 29 subjects, and a dexamethasone suppression test (DST) was performed in 48 subjects. Of the three CSF amine metabolites, only MHPG correlated significantly with baseline TSH and none correlated with ΔTSH. The baseline TSH correlated positively with the TSH response at 30 minutes. Neither baseline TSH nor ΔTSH correlated with cortisol levels before or after dexamethasone. The correlation between CSF MHPG and serum TSH suggests a relationship between central norepinephrine and baseline TSH.

Thyroid Function in Gestational Trophoblastic Tumors

Thyroid function was assessed in a total of 15 cases, 7 of whom had choriocarcinoma and 8 hydatidiform mole, by measuring free T3, free T4, thyroxin-binding globulin (TBG), basal thyroid-stimulating hormone (TSH) and after the thyrotropin-releasing hormone test (delta TSH). Free T3, free T4 and TBG were investigated in the same number of healthy women within the first three months of pregnancy. Only 13.4% of the cases presented elevated levels of free T3 and T4 and TBG; TSH and delta TSH were within normal limits. Both thyroid hormones and TBG returned to within normal limits when beta-human chorionic gonadotropin became undetectable. One patient was found to be hypothyroid. Comparison with the control group showed no significant differences except in TBG levels, which were higher in controls. A significant, direct correlation was found between levels of free T3 and T4 and TBG and the pattern of human chorionic gonadotropin.

Dexamethasone suppression and multiple hormonal responses (TSH, prolactin and growth hormone) to TRH in some psychiatric disorders.

Baseline and TRH-induced changes of thyroid stimulating hormone (TSH), prolactin (PRL), and growth hormone (GH) were measured in 15 healthy control subjects and 63 psychiatric inpatients with DSM-III diagnoses of major depression (n = 19), schizophrenic disorder (n = 20), alcohol dependence (n = 10), and adjustment disorder (n = 14); baseline and postdexamethasone cortisol (CS) were also determined 3-6 days after the TRH-challenge. All patients and controls were women of similar mean age, weight, height, and they were free from interfering illness or drugs. Baseline TSH and PRL were lower in depression, TRH-induced TSH and PRL responses were lower in the whole patient group, but most markedly in depression and alcohol dependence. Postdexamethasone CS was significantly higher in depression, schizophrenia and alcohol dependence. Basal GH did not differentiate the subgroups; TRH-induced pathological GH responses were sometimes found in the patient groups. The differences were most marked quantitatively in major depression: a multivariate analysis of variance showed that delta TSH, postdexamethasone CS and delta PRL were the most important variables in separating patients from controls. A discriminant function derived from these variables classified all controls and 18 of 19 depressed patients correctly; however, 25 of the 44 other patients were also classified with depression. It was confirmed that psychiatric patients show significantly more endocrine disturbances than controls, and this was seen not only in major depression but also in at least three other conditions. Further work is needed to identify other neuroendocrine patterns more specific to depressive disorder.

Using the protirelin test to distinguish mania from schizophrenia.

To explore the possible utility of the protirelin test in differentiating manic and schizophrenic patients, we gave a test dose of protirelin to 30 consecutive euthyroid inpatients who met Research Diagnostic Criteria for mania, 30 who met criteria for schizophrenia, undifferentiated subtype, and 20 normal volunteer controls. The mean maximal thyroid-stimulating hormone (TSH) response (delta TSH) to protirelin in the manic patients was lower than in the schizophrenic patients and in the controls. This mean difference was not attributable to differences in age, sex, baseline thyroid functioning, cortisol levels, or medication, but there was a considerable overlap of values in the patient groups. However, with a delta TSH less than or equal to 7.0 I microunits/mL to identify manic patients in the overall group, the sensitivity of the protirelin test was 60% and the specificity was 84%.

ALTERED DOPAMINERGIC REGULATION OF THYROTROPHIN RELEASE IN PATIENTS WITH PROLACTINOMAS: COMPARISON WITH OTHER TESTS OF HYPOTHALAMIC‐PITUITARY FUNCTION

This study was carried out to test the hypothesis that sustained hyperprolactinaemia in patients with prolactinomas stimulates hypothalamic dopaminergic activity via a short loop positive feedback effect of prolactin (PRL). The intensity of dopamine (DA) effects on the pituitary around the adenoma was evaluated by measuring thyroid stimulating hormone (TSH) responses to intravenous injection of domperidone (10 mg) a new DA receptor blocking drug that does not penetrate the blood-brain barrier. TSH responses have been compared with those of PRL to the same agent. Eight females with prolactinomas showed greater TSH release after domperidone than nine normal females (sum of TSH increments over 20 min 17.5 +/- 1.7 v. 8.9 +/- 1.5 mu/l, P less than 0.001) whilst PRL release was reduced (sum of PRL increments over 120 min 5.9 +/- 2.4 v. 21.8 +/- 3.8 mu/l x 10(-3), P less than 0.01). Amongst nineteen hyperprolactinaemic females with apparently normal pituitary fossae (plain skull X-ray), ten showed an exaggerated TSH response (delta TSH, 4.2 +/- 0.6 mu/l, range 2.5-9.0 mu/1) and reduced PRL response to domperidone, comparable with established tumor cases. In the remaining nine normal fossa hyperprolactinaemic females, the TSH and PRL responses to dopaminergic were similar to normal females. These results support the initial hypothesis and indicate the coexistence of a defect in the dopaminergic inhibition of PRL release and increased dopaminergic inhibition of TSH release in patients with prolactinomas. The presence of an exaggerated TSH response to DA antagonism in a euthyroid, radiologically normal (plain skull X-ray), hyperprolactinaemic patient is compatible with the presence of an autonomously-functioning, PRL secreting, pituitary microadenoma and the TSH changes seen in these patients after DA antagonist administration can be readily detected by sensitive TSH radioimmunoassay.