Normal Thyroid-stimulating Hormone Values Research Articles

Study for optimal dose determination of levothyroxine in subclinical hypothyroidism in pregnancy

Context: Subclinical thyroid dysfunction has been associated with pregnancy complications and affects both maternal and fetal outcomes such as impaired neuropsychological development in offspring and adverse obstetric outcomes-including miscarriage, premature birth, gestational hypertension, placental abruption, and fetal death. Endocrine Society guidelines recommend that all pregnant women with subclinical hypothyroidism be treated with Levothyroxine. The American Thyroid Association guidelines recommend that pregnant women with subclinical hypothyroidism and detectable thyroid-peroxidase antibodies receive Levothyroxine. But till date no authority has given any guideline about the initial dose of Levothyroxine. Aims: To formulate a dosage regime of levothyroxine which is optimal for urgent correction of hypothyroid state in pregnancy. Settings and Design: Prospective (longitudinal) study. Subjects and Methods: A total of 42 apparently normal pregnant women, with known last-menstrual period, with no known metabolic or hypertensive disorder who presented to the clinic had thyroid screening using a standardized method. Women with thyroid stimulating hormone (TSH) value in the range to be diagnosed as subclinical hypothyroidism were included in the study. All patients were followed-up till the time of delivery for the obstetric outcome. Levothyroxine was the mainstay of treatment. Levothyroxine dose were adjusted every trimester on the basis of thyroid function tests (TFTs) including free thyroxine (FT4) and TSH values. Anthropometric measurements included height and body weight at baseline. Statistical Analysis Used: Significance is assessed at 5% level of significance. Pearson and Spearmen correlation test used to find out correlation among normally and non-normally distributed data respectively. Analysis of variance (ANOVA) and Kruskal-wallis with distribution free multiple comparison test used to find the significance of study parameters between three or more groups of patients for normally distributed data and non-normally distributed data. Results: 81.25% of subjects achieved euthyroidism in third trimester. The mean levothyroxine dose used in the first trimester was 40.18 ± 13.78 μg. The mean levothyroxine dose used in the third trimester was 58.25 ± 18.57 μg. Significant increase in the mean dose of levothyroxine required in the third trimester (58.25 ± 18.57 μg) as compared to the first trimester (40.18 ± 13.78 μg, P = 0.0012). Conclusions: Significant improvement in the thyroid function as indicated by higher proportion of patients achieving normal TSH values with significant increase in the mean levothyroxine dose used during the course of treatment gives us guideline about the initial starting doses of levothyroxine.

Subclinical hypothyroidism in children and adolescents after hematopoietic stem cells transplantation without irradiation.

Although total body irradiation (TBI) was considered to be the primary cause of thyroid dysfunction following hematopoietic stem cells transplantation (HSCT), a significant prevalence of subclinical hypothyroidism after HSCT with chemotherapy-only conditioning regimens has been observed in several studies. The aim of this study was to assess changes in thyroid stimulating hormone (TSH) levels in children after HSCT, without the use of irradiation at any time in the course of the treatment. Our cohort consisted of 41 children and adolescents who underwent autologous or allogeneic HSCT and were available for follow-up for at least one year after transplantation. Irradiation was not performed in any of the subjects, neither during pretransplatation therapy, nor during conditioning. The median duration of follow-up was 2.9 years. The indications for HSCT were hematologic malignancy (41.5%), solid malignant tumor (34.1%), and other disorders (24.4%). The thyroid status of all the subjects was assessed prior to HSCT and after follow-up period. Thyroid dysfunction after HSCT was present in 27 (65.8%) subjects. Subclinical hypothyroidism was the most common abnormality, presenting in 23 (56.1%) patients, primary hypothyroidism was present in one (2.4%) patient, while 3 (7.3%) subjects had low free T4 with normal TSH values. Significantly (p < 0.01) higher elevations in TSH levels were present in the patients who received chemotherapy for the underlying disease prior to HSCT. Our findings emphasize the need for long-term monitoring of thyroid function following HSCT, regardless of whether or not irradiation was used.

Female vulnerability for thyroid function abnormality in bipolar disorder: role of lithium treatment

Previous studies have provided evidence of subtle thyroid hormone metabolism abnormalities in patients with mood disorders. Although these studies are informative, the precise role of the hypothalamic-pituitary-thyroid axis in bipolar disorder, especially in women, remains unclear. We sought to further corroborate thyroid function in patients with bipolar disorder in comparison to patients with other psychiatric, as well as non-psychiatric, diagnoses. In this retrospective, cross-sectional, naturalistic study, serum thyroid-stimulating hormone (TSH) levels in a total sample of 3,204 patients were compared. The study sample included patients with bipolar disorder (n = 469), unipolar depression (n = 615), and other psychiatric diagnoses (n = 999), patients from endocrinology clinics (n = 645), and patients from dermatology clinics (n = 476). Analyses were completed using two different normal ranges for TDH: a high normal range (0.4-5.0 μIU/mL) and a low normal range (0.3-3.0 μIU/mL). Patients with bipolar disorder showed significantly higher serum TSH levels compared to all other groups. In women, the rate of above normal range TSH was highest in patients with bipolar disorder for both high (5.0 μIU/mL; 12.1%) and low (3.0 μIU/mL; 30.4%) upper normal limits. In patients with bipolar disorder, serum TSH levels did not differ significantly between different mood states. In the lithium-treated patients (n = 240), a significantly lower percentage of women (55.9%) compared to men (71.2%) fell within the 0.3-3.0 μIU/mL normal TSH window (p = 0.016). For the high normal range (0.4-5.0 μIU/mL), serum lithium levels above 0.8 mmol/L were associated with a significantly lower proportion of female patients (59.2%) falling within the normal range than male patients (88.9%). Non-lithium treatment was not associated with a gender difference. Our findings show a higher rate of TSH abnormality in patients with bipolar disorder, particularly those taking lithium, compared to those with other psychiatric and medical conditions. Lithium-associated thyroid dysregulation occurs more frequently in female patients. Using the low normal range TSH values at follow-up can increase sensitivity in recognizing hyperthyroidism in lithium-treated female patients, and help in preventing the development of subclinical hypothyroidism and an adverse course of illness.

Levothyroxine Dosage Is Associated with Stability of Thyroid-stimulating Hormone Values

ObjectiveIn patients treated for hypothyroidism, the usual practice is to monitor thyroid-stimulating hormone values yearly once a therapeutic dosage of levothyroxine is determined. This study investigates whether there are any clinical predictors that could identify a subset of patients who might be monitored safely on a less frequent basis. MethodsWith the use of a retrospective study design, 715 patients treated for hypothyroidism who had a normal (ie, therapeutic) thyroid-stimulating hormone value in 2006 while taking levothyroxine were identified. All thyroid-stimulating hormone values were then obtained through December 31, 2012. By using a Cox proportional hazard model, gender, age, body mass index, history of chronic autoimmune thyroiditis, initial thyroid-stimulating hormone level, and levothyroxine dose were analyzed for time to first abnormal thyroid-stimulating hormone value. ResultsAge, gender, history of chronic autoimmune thyroiditis, and body mass index at the time of initial normal thyroid-stimulating hormone were not associated significantly with time to abnormal thyroid-stimulating hormone value. Levothyroxine dose >125 μg/day had an increased hazard ratio of 2.4 (95% confidence interval, 1.7-3.4; P < .0001) for time to first follow-up abnormal thyroid-stimulating hormone value, but dosages less than that did not increase the hazard ratio. One year after the initial normal thyroid-stimulating hormone value, 91.1% of patients taking ≤125 μg/day had a continued normal thyroid-stimulating hormone, whereas only 73.3% of patients taking >125 μg/day did. Transformed thyroid-stimulating hormone value (which represents a measure of how far the initial thyroid-stimulating hormone was from the midpoint of the normal range) also had an increased hazard ratio of 1.14 (95% confidence interval, 1.1-1.2; P < .0001) for time to first abnormal thyroid-stimulating hormone value. ConclusionsFor patients receiving ≤125 μg/day of levothyroxine, we propose that a testing interval up to 2 years may be acceptable if their thyroid-stimulating hormone is well within the normal range.

PREVALENCE OF THYROID DYSFUNCTION AND ITS MANAGEMENT IN DIABETIC PATIENTS ATTENDING OUTPATIENT CLINIC OF KIMS HOSPITAL

Thyroid dysfunction is one of the parameter for poor glycemic control. In hypothyroidism, the synthesis and release of insulin is decreased, while in hyperthyroidism, there could be masking of increase in insulin secre tion due to increased degradation of insulin . We did our study in the prevalence of thyroid dysfunction and its t reatment management in Type 2 D iabetes M ellitus (DM) patients. The study was conducted for period of 6 months from January to June 2012 . During the study w e recruited Type 2 DM patients attended the clinic who were receiving insulin’s, antidiabetic drugs more than 5 years and confirming with fasting plasma glucose levels of > 110 mg/dl at more than two occasions, visited the medicine outpatient d epartment at KIMS Hospital, Bangalore , India who were screened and included into the study after explaining about the study followed by taking the informed consent from the participants . The total of 223 , Type 2 DM patients data were recorded in a well - des igned data collection form. Blood sample was dra wn for thyroid stimulating hormone (TSH) analysis and the obtained value was recorded. W e found that the percentage of female’s 18 (8.07 %) patients suffering from hypothyroidism was higher than men six (2.69 %) patients. We also found that the percentage of female’s 17 (7.62 %) patients suffering from hyperthyroidism was also higher than men 13 (7.62 %) patients . Out of 223 patient’s recruited T ype DM patients, 169 (75.78 %) patients were found to have normal TSH values and remaining 54 (24.21 %) patients were diagnos ed to have thyroid dysfunction, out of which 30 (13.45 %) patients had hyperthyroidism and 24 (10.76 %) patients had hypothyroidism. Thyroid dysfunction is one the reason for poor glycemic control in diabetic patients. Under or inadequate treatment of thyroid dysfunction can negatively impact on the diabetics control.

Reversing Hypometabolic Symptoms by Normalizing Low Body Temperatures with Sustained-release T3 in Patients with Euthyroid TSH Levels

OBJECTIVE:&nbsp;Currently, the position of the American Thyroid Association is that hypothyroidism causes symptoms of metabolic slowing due to inadequate production of thyroid hormone by the thyroid gland; it is diagnosed by a lab result of a high thyroid stimulating hormone (TSH) level. While hypothyroidism is considered a chronic, incurable condition, the symptoms typically can be controlled by ingestion of thyroxine (T4) for life. Due to this conclusion, medical providers overall adhere to the assumption that people with normal TSH levels can not have thyroid-hormone-responsive symptoms; likewise, thyroid-hormone-responsive symptoms should not be treated with triiodothyronine T3 and are not reversible. Our objective was to examine if treatment with sustained-release (SR-T3), in patients with normal TSH values and low body temperatures, reduced symptoms consistent with low metabolic rate—and if improvement in symptoms remained even after discontinuation of the T3 treatment regimen. INTERVENTIONS:&nbsp;We report the results of 11 euthyroid outpatients with low body temperatures who took oral SR-T3 every 12 hours according to a cyclic dosing schedule designed to titrate low body temperatures to normal. The SR-T3 they took was formulated with the aim of delivering the T3 gradually over 12 hours. RESULTS:&nbsp;All of the patients in this study responded with an elevation in oral temperatures and improvement in five symptoms measured following the T3 treatment regimen. CONCLUSION:&nbsp;Patients exhibiting hypometabolism with normal TSH levels may experience a reversal of symptoms with normalization of low body temperatures on administration of a sustained-release T3 regimen such that their symptoms remain improved after the regimen has been discontinued.

Hypothyroidism in preterm infants following normal screening

Congenital hypothyroidism is screened for in the UK using blood spot thyroid-stimulating hormone (TSH) screening at 5-8 d of age. Although standards are set by the UK Newborn Screening Programme Centre, there are variations in TSH cut-offs used. The introduction of repeat screening of preterm babies at 36 weeks' gestational age in 2005 was controversial in its utility and timing. Two cases of preterm babies are presented, who had normal blood spot TSH values on the first test and who became screen positive when re-tested at term. The first with Trisomy 21 was born at 29 + 6 weeks with an initial blood spot TSH of 3.3 mU/L rising to 263 mU/L at term-corrected gestational age (plasma TSH 476.5 mU/L). The second was born at 24 + 6 weeks' gestational age and on day 7, the heel prick blood spot TSH was <2 mU/L, rising to 6.4 mU/L at 36 weeks corrected gestational age. After a barium enema, the plasma TSH increased to 66.6 mU/L with a free thyroxine of 7.6 pmol/L at day 101. Both cases were treated with thyroxine until death due to complications of prematurity. These cases illustrate the difficulties in screening for congenital hypothyroidism in preterm infants, due to the immaturity of the hypothalamo-pituitary-thyroid axis, and the effect of intercurrent illness and drugs on thyroid function. Despite a reassuring published review of 2200 preterm infants, these cases suggest that it may be unwise not to re-screen ex-preterm infants for congenital hypothyroidism at term.

Obstetric outcome in women with hepatitis C virus infection and thyroid dysfunction

OBJECTIVES. To determine the incidence of thyroid abnormality in pregnant women with hepatitis C virus (HCV) infection and evaluate pregnancy outcomes with respect to thyroid function status. DESIGN. Prospective cohort study. SETTING. Tertiary care hospital. POPULATION. Pregnant women with HCV infection. METHODS. Seventy-eight HCV positive women had radioimmunoassay thyroid function tests. All were followed until delivery. Pregnancy outcomes were compared in women with and without subclinical hypothyroidism. MAIN OUTCOME MEASURES. Maternal and perinatal outcomes. RESULTS. Of 78 anti-HCV antibody positive pregnant women, 13 (16.7%) had abnormal thyroid-stimulating hormone (TSH) (>5 mIU/L; hypothyroid group) and the remaining 65 (83.3%) had normal TSH values (euthyroid group). None had abnormal free T4 levels. None showed evidence of fetal distress in labor or fetal asphyxia. In the hypothyroid group, 23% compared to 6.2% in euthyroid group underwent cesarean section (p=0.07). The incidence of preterm delivery (7.7% vs. 24.6%; p=0.28), mean gestation at delivery (38.2+/-1.8 vs. 37.5+/-1.8 weeks, p=0.19), and birthweight (2,687+/-430 g vs. 2,846+/-379 g, p=0.18) was comparable. Neonatal nursery admissions were comparable. CONCLUSION. The presence of subclinical hypothyroidism in pregnant women with HCV infection does not adversely affect short-term pregnancy outcomes.

Impact of total versus subtotal thyroidectomy on calcium metabolism and bone mineral density in premenopausal women

This study aimed to compare the impact of total versus subtotal thyroidectomy on calcium metabolism and bone mineral density in euthyroid, premenopausal women. The study included 24 premenopausal women who had undergone total (n = 10) or subtotal (n = 14) thyroidectomy and who were receiving nonsuppressive doses of thyroxine. The median post-operative period was four years. We determined, in all patients, the following parameters associated with calcium metabolism: total serum calcium, inorganic phosphate, intact parathormone, calcitonin and alkaline phosphatase. The bone mineral density of the spine and hip were measured using a Hologic QDR 4500C bone densitometer and were compared with controls matched for age and peak bone mineral density (using the t-test). The measured calcium metabolism parameters were normal in all patients, and none had osteoporosis. There was no significant difference in the bone mineral density measurements for the spine and hip, comparing patients who had undergone total versus subtotal thyroidectomy (using the t-test). The impact of total thyroidectomy on bone mineral metabolism is not significantly different from that of subtotal thyroidectomy, in premenopausal women with normal thyroid-stimulating hormone values.

Association Between Elevated Serum C-Reactive Protein and Triglyceride Levels in Young Subjects With Type 1 Diabetes

Cardiovascular disease is the major cause of mortality and morbidity in individuals with diabetes (1,2). Increased plasma concentrations of acute-phase proteins have been reported in adult patients with either type 2 (3,4) or type 1 (5,6) diabetes. However, there have been few studies to determine plasma high-sensitivity C-reactive protein (hs-CRP) levels in young diabetic patients (7,8). This study evaluated the levels of hs-CRP and their correlation with metabolic profile in very young patients with type 1 diabetes. This sectional study included 45 consecutive young patients (26 boys) who fulfilled the inclusion criteria (diagnosed as type 1 diabetic, followed up at a public health assistance center, serum creatinine level <1.3 mg/dl, and normal thyroid-stimulating hormone values) and 30 healthy subjects (12 boys) matched by age (±3 years) and BMI. Exclusion criteria were hypertension, overweight or obesity, smoking, any infection having been diagnosed during the previous 3 months, and treatment for inflammatory or chronic infectious disease. Measurements of pulse rate, blood pressure, height and weight, and specific clinical examination of throat, eyes, nose, ears, skin, and feet were performed. Laboratory data included fasting blood glucose, HbA1c (A1C), total cholesterol, HDL and LDL cholesterol, triglycerides, serum creatinine, thyroid-stimulating hormone, and hs-CRP. Hs-CRP was determined by nephelometry. Differences in the means were evaluated by the Student’s t test. The hs-CRP data were …

Medication and low serum thyroxine values in nursing home residents.

The nursing home clinician may encounter euthyroid residents with low total serum thyroxine (T4) values associated with certain medications or nonthyroidal illness (NTI). Hypothyroidism may be incorrectly diagnosed and thyroid hormone prescribed. We reviewed all T4 determinations and individuals with low T4 and normal thyroid-stimulating hormone (TSH) levels were identified. Pharmacy and medical records were reviewed. We reviewed 1,153 T4 determinations and identified 22 individuals with low T4 and normal TSH values. Eight of the 22 (36%) were being treated with high-dose salicylates, 4 (18%) with phenytoin, 3 (14%) with carbamazepine, and 2 (9%) with prednisone (15 mg/day). Three residents were on two of these medications. None was on prednisone as a single medication. Eight were on none of the medications, and 5 of these had albumin values of < or = 3.2 g/dL (a marker of NTI). After a low T4 value was determined in these individuals, 6 of the 22 were placed on T4 replacement with no documentation of hypothyroidism. In 5 of these, low T4 level could be attributed to a medication effect. Low total T4 with normal TSH levels are commonly associated with medications and NTI.

Newborn Screening for Congenital Hypothyroidism: Recommended Guidelines

During the past decade newborn screening for congenital hypothyroidism has become an important health activity in most developed countries. These screening programs have not only benefited patients and their families but also have produced new information about the epidemiology, pathophysiology, diagnosis, and treatment of thyroid disease in infancy and childhood. During this period of implementation and growth of the screening programs, a variety of issues and questions arose. Some of these have been resolved, and some have not. The point has now been reached where collation of the combined experiences of the North American programs can address these issues. The reader should understand that what follows reflects current opinion and may require changes when the results of the next decade of screening are reviewed. SCREENING METHOD Thyroxine (T4) and Thyroid-Stimulating Hormone (TSH) Most North American programs use a two-tiered laboratory approach. An initial T4 measurement is followed by measurement of TSH in specimens with low T4 values. In addition to detecting infants with primary hypothyroidism (low or low normal T4 level with elevated TSH value; prevalence 1:3,500 to 4,500 newborns), this approach can also identify infants with thyroxine-binding globulin deficiency and some with hypothalamic-pituitary hypothyroidism (low or low normal T4 level with normal TSH value; prevalence 1:5,000 to 10,000 and 1:50,000 to 150,000 newborns, respectively). Programs that quantify T4 values also have the option of identifying newborns with hyperthyroxinemia (1:20,000 to 40,000 newborns). On the other hand, this approach will miss infants who have normal T4 values but elevated TSH values. Such infants are relatively commonplace in European programs where initial screening is done by measurement of TSH.