Median TSH Values Research Articles

Thyroid function profile, and its association to consumption of cassava and <i>Moringa stenopetala</i> in pregnant women

Background: Pregnancy is associated with the change in thyroid function. Thyroid function is also affected by goitrogenic substances in some plant foods, like cassava. Aim: This study aims to assess thyroid function status and its association to consumption of foods containing goitrogenic substances. Methods: A cross sectional study was done on a total of 65 pregnant women attending Sawla Health Center, South Ethiopia. Serum samples were collected and analyzed for TSH, total T4 and total T3 by using ELISA kit. Data on consumption of foods containing were obtained from food frequency questionnaire. Results: The median TSH of the first, second and third trimesters, respectively are 2.57, 1.86 and 2.42 mIU/L, which are within the reference interval (0.30-6.20 mIU/L) of the test kit. The median total T4 values (9.8, 10.0 and 10.3 μg/dl in the first, second and third trimesters, respectively) were also within the reference interval (4.8-11.6 μg/dl) of the test kits. The median total T3 in the first (2.60 ng/ml) and third (2.35 ng/ml) trimesters were elevated, but it was within the reference interval (0.69-2.02 ng/ml) in the second trimester (1.92 ng/ml). Though statistically non-significant median TSH was increased in women grouped as cassava consumers and M. stenopetala consumers while median total T4 values were decreased in these groups. Conclusion: The study subjects have normal thyroid function as the median values of TSH and total T4 were within the reference interval of the test kit. Frequent consumption of cassava and Moringa stenopetala may affect thyroid function.

The incidence of thyroid function abnormalities and natural course of subclinical thyroid disorders, Tehran, I.R. Iran.

Despite the high prevalence of thyroid dysfunction, the epidemiology and natural course of these disorders have not been identified yet. The present survey was conducted to determine the incidence of thyroid dysfunction and natural course of subclinical thyroid disorders in an urban community of Tehran, I.R. Iran. Serum TSH and thyroperoxidase antibody (TPOAb) were measured at baseline and after 6.7 yr from a sample of 1999 randomly selected subjects aged≥20 yr, participants of the Tehran Lipid and Glucose Study (TLGS). Median TSH value and 2.5, 5, 95, and 97.5 TSH percentiles were determined at baseline using data obtained from 808 negative TPOAb subjects with no history of any thyroid disease or surgery, goiter, nodule, taking thyroid hormone preparations or anti-thyroid drugs. In those with abnormal TSH level, total T4 and T3 uptake were measured and free T4 index was calculated. Normal TSH reference range was 0.4-5.8 μU/ml according to the 2.5 and 97.5 TSH percentiles. The incidence rates of thyroid function abnormalities in 1000 subjects per year were as follows: clinical hypothyroidism: 0.28 in women and 0.21 in men; subclinical hypothyroidism: 11.59 in women and 4.69 in men; clinical hyperthyroidism: 1.4 in women and 0.21 in men; and subclinical hyperthyroidism: 5.72 in women and 3.62 in men. A significant increase was found in the frequency of positive TPOAb in women from 15.9 to 17.7% (p=0.006). Of 8 women with subclinical hypothyroidism at baseline, 5 remained unchanged, 1 became normal, and 1 developed clinical hypothyroidism at followup. Two women with subclinical hyperthyroidism normalized at follow-up. Of 2 men with subclinical hypothyroidism at baseline, 1 remained unchanged, whereas the other progressed to clinical hypothyroidism. After a 6.7 yr follow-up significant increase in the incidence of subclinical thyroid disorders was observed in both men and women, as compared to overt thyroid dysfunction. Increase in the prevalence of TPOAb positivity was observed only in women.

Age Modifies the Pituitary TSH Response to Thyroid Failure

To investigate the association between serum TSH, total T4 and various patient characteristics when hypothyroidism is diagnosed in a population, and to study how age, sex and serum T4 levels influenced pituitary TSH response. A computer-based register linked to laboratory databases prospectively identified all patients with new, biochemically overt hypothyroidism (n = 685) in an open cohort in Denmark. The diagnosis was verified in each patient, and disease was classified into nosological type. Serum TSH and total T4 were recorded at the time of diagnosis in untreated patients with spontaneous autoimmune hypothyroidism (n = 578). In untreated primary, spontaneous autoimmune hypothyroidism, we observed a four fold difference in average serum TSH levels between the youngest (0-20 years: TSH = 100 mU/l) and the oldest (80+ years: TSH = 24.4 mU/l) group of patients. No age dependent variation was observed in serum total T4. Log TSH showed an inverse linear correlation with age. An inverse linear correlation was present between log TSH and total T4 in both young and old patients, but for all total T4 values we observed lower median serum TSH values in elderly patients. For the same degree of thyroid failure, the serum TSH is lower among the elderly. This is most likely caused by a decrease in the hypothalamic/pituitary response to low serum T4. A certain increase in serum TSH may indicate more severe hypothyroidism in an old than in a young patient, and longer time may be needed after thyroid hormone withdrawal before elderly patients with thyroid cancer reach sufficiently high TSH values to allow for an effective radio-iodine treatment.

Prevalence of solitary hot, cold and normal functioning thyroid nodules in patients with first evaluation for a solitary thyroid nodule

Functional properties of thyroid nodules are defined by their ability for increased, normal or decreased radionuclide uptake on scintiscanning, resulting in a classification as hot (HTN)/warm/WTN), normal functioning (NTN) or cold thyroid nodules (CTN). In a multi-centre pilot study conducted in Saxony (n=103 patients) Westfalia (n=209 patients) and Bavaria (n=153 patients), we addressed the question of (I) present distribution of solitary hyper-/hypo- and normal functioning thyroid nodules in Germany and (II) whether a correlation exists between the TSH-value and nodular function in euthyroid patients with solitary thyroid nodules. Clinical and biochemical data, thyroid ultrasound and scintiscan results were obtained from 466 consecutive patients (348 women, 118 men, aged 19–87 yr.) presenting for a first evaluation of a solitary thyroid nodule >1cm. Scintiscan showed 19% hot (complete suppression of surr. tissue), 18% warm (increased focal uptake with no suppression of surr. tissue;WTN), nodules, 39% normal functioning and 24% cold thyroid nodules. Except for a slightly higher prevalence of thyroid autonomy in Saxony, the distribution of functional nodule characteristics was similar in the three Bundeslander. Median TSH values (mU/l) were ~0.1 in HTN (range <0.01–0.4), ~0.8 in WTN (range 0.1–2.3), ~0.85 in NTN (range 0.1–2.05) and ~0.9 in CTNs (range 0.1–2.45). While all HTN had TSH-values <0.4, there were no significant differences in the overall TSH values for WTN, NTN and CTN. The median volumes were 7ml in HTN, 2.3ml in WTN, 2.3ml in NTN and 4ml in CTN. Age distribution of the investigated patients showed a trend towards higher age in patients with HTN (median 59yrs) compared to WTN, NTN and CTN (median 49–52yrs). Our data indicate persisting high prevalence of thyroid autonomy in Germany despite past improvements in the iodine supply. The tendency towards higher prevalence of HTN in larger nodules and older patients is in agreement with other epidemiological studies showing increased prevalence of thyroid autonomy in older age groups.

Where does subclinical hypothyroidism start?

SummaryThe upper limit of the TSH reference range is currently under discussion. In its recent guidelines, the National Academy of Clinical Biochemistry (NACB) recommended the use of ~2.5 mIU/L, rather than ~4 mIU/L, due to the fact that reference populations, on which the definition of the reference range is based, contain persons undergoing an initial phase of autoimmune thyroid disease. This will skew the upper reference limit of TSH. Ultrasonography, in addition to measurement of thyroid autoantibodies, should be used to exclude these persons. Objective: The present study investigates whether the NACB recommendation also applies for a region of mild iodine deficiency. Methods: According to NACB criteria, a reference population (713 persons) was defined out of a total study population of 1442. The TSH reference range was calculated in this reference group and in further subgroups by percentiles. The results were compared with the total study population and the NACB recommendation. All assays used were provided by BRAHMS Diagnostica AG, Hennigsdorf, Germany. Results: As expected, all median TSH values, excluding the median of the group with a hypoechogenic thyroid were close to 1.2 mIU/L. The 97.5th percentile in the reference population was 3.35 mIU/L. However, there was no difference compared to the total study population. Conclusion: The upper reference limit for TSH based on a reference population according to NACB criteria came down to 3.35 mIU/L, but not to ~2.5 mIU/L. Interestingly, there is no difference compared to the total study population.

Changes in iodine metabolism during late pregnancy and lactation: a longitudinal study among Sudanese women.

To elucidate the persistence, or otherwise, of the pregnancy-related changes in the iodine metabolism and thyroid function in a population residing in an area of mild iodine deficiency in the Sudan. A longitudinal prospective cohort study involving pregnant women who were recruited during their third trimester of pregnancy and were followed up for up to nine months after delivery. The study was conducted among Sudanese women residing in the Omdurman area in Khartoum, an area with a total goitre rate of 17.5%. Forty-seven pregnant women were recruited during their third trimester of pregnancy. Their mean age and weight were 29+/-4.6 y and 62.4+/-8.7 kg, respectively. Age matched healthy non-pregnant women living in the same area (n=40) served as a control group. Serum levels of thyrotropin (TSH), thyroxine (T4), triiodothyronine (T3), thyroglobulin (Tg) and the urinary iodine concentration (UIC) were determined during the third trimester (first occasion), and subsequently at three months (second occasion), six months (third occasion) and nine months after delivery (fourth occasion). Control subjects provided corresponding samples on one occasion. UIC, TSH, Tg, FT4 and T3. During the third trimester of pregnancy the median UIC and the free T4 (FT4) were lower than in the control group (P<0. 0001, P<0.0001, respectively), while the median Tg was higher than in the controls (P<0.03). Three months post-partum maximum thyroidal stimulation was evident, with elevated serum levels of TSH and Tg (P<0.0001, P<0.03) and reduced UIC and serum T3 and FT4 (P<0.0004, P<0.0005, P<0.0001), compared with the control group. Nine months post-partum the thyroid function was restored to the pre-pregnancy state, and the median values of TSH, Tg, T3, FT4 and UIC did not differ significantly from those in the control group. Our study suggests that the reversibility of the pregnancy-induced changes in the iodine status and thyroid function to the pre-pregnancy levels may depend on the iodine status of the mother during and after pregnancy. The thyroidal stress during the first three months of the post-partum period, which is partially due to the iodine loss in the breast milk, justifies further detailed studies to assess the iodine content of the breast milk and the role of breast milk as a vehicle for iodine supply of infants in situations of iodine deficiency. This study was supported by a grant from the Swedish Agency for Research Co-operation with Developing Countries.

Effect of oral iodized oil on thyroid size and thyroid hormone metabolism in children with concurrent selenium and iodine deficiency.

To determine the efficacy of oral iodized oil in goitrous children who are both selenium (Se) and iodine deficient; to investigate if Se status modifies the response of iodine deficient, goitrous children to oral supplementation with iodized oil. A longitudinal intervention trial. Two rural villages in the western Côte d'Ivoire. 51 goitrous non-anemic schoolchildren with both iodine and Se deficiency. Each child received an oral dose of 0.4 ml iodized poppyseed oil containing 200 mg of iodine. They were followed for 1 y with measurements of urinary iodine (UI), thyrotropin (TSH), thyroxine (T4), and thyroid volume by ultrasound. At baseline all children were goitrous and Se deficient; median UI was 29 microg/l and mean serum Se (s.d.) was 14.8 (10.7) microg/l. After receiving iodized oil, thyroid volume decreased significantly vs baseline at 10, 15, 30 and 50 weeks (P<0.001). At 50 weeks mean percentage change in thyroid volume from baseline was-46.6% and only five children remained goitrous. Median TSH values at 5, 10, 15, 30 and 50 weeks were reduced significantly (P<0.001) compared to baseline. Among individual children the severity of Se deficiency predicted the degree of response to iodized oil. Baseline serum Se and percentage change in thyroid volume from baseline at 50 weeks were strongly correlated (r2=0.554). Baseline Se and percentage decrease in TSH from baseline at 30 weeks were also well-correlated (r2=0.467). Although more severe Se deficiency partially blunts the thyroid response to iodine supplementation, oral iodized oil is an effective method for iodine repletion in goitrous children who are Se deficient. The Swiss Federal Institute of Technology, Zürich, the Foundation for Micronutrients in Medicine, Rapperswil, Switzerland, and the Thrasher Research Fund, Salt Lake City, USA.

The effects of different doses of oral iodized oil on goiter size, urinary iodine, and thyroid-related hormones.

The prevention of iodine deficiency is still a worldwide concern. This study, conducted in Soja in western Sudan, was carried out to evaluate the effects of a dose of iodized oil sufficient enough to give maximum protection against goiter and provide an acceptable iodine supply without side-effects over a sufficiently long period of time. Adult goitrous subjects (n = 117) were randomly assigned to three groups, A, B, and C, and received a single oral dose of 200, 400, or 800 mg iodine, respectively. Urine and blood samples were collected at the start of the study and monitored for 1 yr. In the 3 groups, mean serum T4 and median urinary iodine and serum TSH values were restored to reference limits, and these were maintained for about 1 yr. In each treatment group, about two thirds of the subjects displayed a reduction in goiter size, and the 400- and 800-mg doses were not more efficient than the 200-mg dose to accomplish normalization of thyroid hormone values. A temporary rise in TSH was noted 1 week after iodine administration in 1, 3, and 10 subjects, respectively, and 1, 0, and 3 subjects showed biochemical signs of thyrotoxicosis during the year after treatment with the 3 different doses. The data indicate that oral administration of 200 mg iodine is effective and acceptable for treating iodine deficiency in adults for 1 yr. Because of the risks of side-effects and the shortage of medical resources, higher doses are not recommended.

Iodine in contrast agents and skin disinfectants is the major cause for hypothyroidism in premature infants during intensive care.

In 51 sick newborns the influence of two different nonionic, iodine-containing contrast agents, Amipaque (group 1) and Omnipaque (group 2) and of long-term treatment with polyvinylpyrrolidone-iodine (PVP-I) (group 3) on thyroid function was studied. In the dose given, freshly dissolved Amipaque releases roughly 100 micrograms 'free' iodide/kg body weight; this release may be even higher in the solubilized agent Omnipaque because of increased breakdown. Urinary iodine excretion was elevated in all groups on day 5 after iodine exposure. In group 1, which included 17 term newborns, the median TSH level was normal after 5 days and 2 weeks, only 1 case of transient hypothyrotropinemia was observed; T4 and T3 median levels were in the lower range of normal. In groups 2 and 3, which included 8 preterm infants of 15 newborns and 9 preterm infants of 19 newborns, respectively, the median TSH values were elevated and T4 and T3 levels were very low. Hypothyroidism was diagnosed in 6 of the 8 preterm and in 1 of the 7 term newborns of group 2. In group 3, 7 of the 9 preterm and 3 of the 10 term newborns reacted with hypothyroidism. Eight preterm and 3 term newborns had to be substituted with thyroxine. The thyroid function of term newborns was less affected by Amipaque or Omnipaque than by PVP-I. The data show that preterm infants are very sensitive to an iodine load.