Thyroid Hormone and Thyrotropin Concentrations and Responses to Thyrotropin-Stimulating Hormone in Horses with PPID Compared with Age-Matched Normal Horses

Glucocorticoids are known to exert inhibitory action on the hypothalamic-pituitary-thyroid axis. With recent evidence that free plasma cortisol and urinary excretion of cortisol metabolites may be increased in horses with pituitary pars intermedia dysfunction (PPID), it is important to further examine thyroid function in horses with PPID. To test the hypothesis that serum thyrotropin (TSH) concentrations are decreased in horses with PPID, baseline serum thyroid hormone and TSH concentrations, and responses to TSH-releasing hormone (TRH), were compared between 12 horses diagnosed as having PPID and 14 age-matched normal horses. Horses with PPID had resting serum concentrations of free thyroxine by equilibrium dialysis (fT4D) and TSH that were significantly lower than serum concentrations of fT4D and TSH in age-matched normal horses. Serum concentrations of total T4 and total and free triiodothyronine (T3) were also lower in horses with PPID compared with normal horses, but the differences did not reach statistical significance. Thyroid hormone and TSH responses to TRH administration were not different between horses with PPID and normal horses. In conclusion, serum fT4D concentrations are decreased in horses with PPID without an appropriate increase in serum TSH concentrations. Normal serum thyroid hormone and TSH concentration responses to exogenous TRH administration support the theory that increased glucocorticoid activity in horses with PPID may exert prolonged tonic suppression, but not complete inhibition, of TRH and subsequent TSH release, similar to what has been observed in other species.

CAD system based on B-mode and color Doppler sonographic features may predict if a thyroid nodule is hot or cold

OBJECTIVES

The aim of this study was to evaluate if the analysis of sonographic parameters could predict if a thyroid nodule was hot or cold.

METHODS

Overall, 102 thyroid nodules, including 51 hyperfunctioning (hot) and 51 hypofunctioning (cold) nodules, were evaluated in this study. Twelve sonographic features (i.e., seven B-mode and five Doppler features) were extracted for each nodule type. The isthmus thickness, nodule volume, echogenicity, margin, internal component, microcalcification, and halo sign features were obtained in the B-mode, while the vascularity pattern, resistive index (RI), peak systolic velocity, end diastolic velocity, and peak systolic/end diastolic velocity ratio (SDR) were determined, based on Doppler ultrasounds. All significant features were incorporated in the computer-aided diagnosis (CAD) system to classify hot and cold nodules.

RESULTS

Among all sonographic features, only isthmus thickness, nodule volume, echogenicity, RI, and SDR were significantly different between hot and cold nodules. Based on these features in the training dataset, the CAD system could classify hot and cold nodules with an area under the curve (AUC) of 0.898. Also, in the test dataset, hot and cold nodules were classified with an AUC of 0.833.

CONCLUSIONS

2D sonographic features could differentiate hot and cold thyroid nodules. The CAD system showed a great potential to achieve it automatically.

KEY POINTS

• Cold nodules represent higher volume (p = 0.005), isthmus thickness (p = 0.035), RI (p = 0.020), and SDR (p = 0.044) and appear hypoechogenic (p = 0.010) in US. • Nodule volume with an AUC of 0.685 and resistive index with an AUC of 0.628 showed the highest classification potential among all B-mode and Doppler features respectively. • The proposed CAD system could distinguish hot nodules from cold ones with an AUC of 0.833 (sensitivity 90.00%, specificity 70.00%, accuracy 80.00%, PPV 87.50%, and NPV 75.00%).

Hypothyroidism during pregnancy and its association to perinatal and obstetric morbidity: a review

There is currently no consensus among the different scientific societies on screening for thyroid dysfunction in the first trimester of pregnancy. Indeed, diagnosis and treatment of subclinical hypothyroidism during pregnancy are controversial, as no cut-off value for thyrotropin (TSH) is universally accepted. TSH measurement may be influenced by different factors throughout pregnancy, but especially during the first trimester. The association between overt hypothyroidism during pregnancy and obstetric and perinatal complications is well established. It is also accepted that thyroid hormones are important for neurodevelopment of the offspring. However, there is no scientific evidence available about the impact of subclinical hypothyroidism and its treatment during the first trimester of pregnancy on children's neurodevelopment. In recent years, studies conducted in the offspring of mothers with subclinical hypothyroidism have reported new biochemical parameters which may eventually serve as biomarkers of offspring neurodevelopment and which are more reproducible and are measured at an earlier time than the conventional clinical tests.

Hyperphagia in short bowel patients: Fat-free mass is a strong predictor

OBJECTIVES

Some patients with short bowel syndrome (SBS) develop hyperphagic behavior. Such an increase in food intake stimulates intestinal adaptation and limits dependence on parenteral nutrition (PN). The aim of this study was to determine the factors modulating food consumption in patients with SBS.

METHODS

The associations between oral energy intake (OEI) and anthropometric, metabolic, nutritional, and intestinal absorption-related characteristics were determined in a monocentric cohort of patients with SBS on PN with a stable nutritional status. Body composition was assessed by dual x-ray absorptiometry. Data were retrospectively collected from clinical records.

RESULTS

After screening, 38 adult patients with a SBS on PN were included in this study. OEI ranged from 577 to 4054kcal/d. OEI correlated positively with weight, fat-free mass, handgrip strength, and resting energy expenditure (REE) and negatively with free triiodothyronine and C-reactive protein using Spearman correlation. Fat-free mass and thyroid-stimulating hormone remained positively correlated with OEI independently of all other parameters in a multilinear regression model.

CONCLUSIONS

Fat-free mass is a strong predictor of OEI in patients with SBS on PN and without debilitating gastrointestinal symptoms. Increasing fat-free mass could be a way to stimulate OEI in these patients. Further studies are needed to assess this assumption.

Thyroid function is associated with body mass index and fasting plasma glucose in Thai euthyroid population

AIMS

Several population-based studies found the associations between body mass index and thyroid function within the normal range. Furthermore, these thyroid functions are related with insulin resistance and plasma glucose levels. This study aimed to investigate the associations between thyroid functions and metabolic parameters in Thai euthyroid population.

METHODS

Participants from the Thai National Thai Health Examination Survey were randomly measured for TSH, FT4, anti-thyroperoxidase, and anti-thyroglobulin. Euthyroidism was defined by TSH 0.27-4.20 mIU/L and FT4 0.93-1.71 ng/dL.

RESULTS

A total of 2242 euthyroid participants were included. Fifty-one percent were female. Mean age, fasting plasma glucose, and body mass index were 55 ± 21 years, 93 ± 29 mg/dL, and 23.4 ± 4.6 kg/m², respectively. Multivariate regression analysis after age and sex adjustment showed a negative association of serum FT4 with body mass index (β = -0.070, p = 0.001) and the relationship was still significant after subjects with positive anti-thyroperoxidase were excluded (β = -0.068, p = 0.003). In contrast, serum TSH was positively associated with body mass index (β = 0.052, p = 0.012). Moreover, serum FT4 was positively associated with fasting plasma glucose levels (β = 0.097, p < 0.001).

CONCLUSIONS

Small variations of serum TSH and FT4 within the reference range may contribute to the differences in metabolic indexes such as body mass index and fasting plasma glucose.

Effects of thyroid-stimulating hormone on adhesion molecules and pro-inflammatory cytokines secretion in human umbilical vein endothelial cells

Atherosclerosis is a multifactorial disorder, which affects the arterial wall. It has been reported that, hypothyroidism and thyroid hormone deficiency are related to cardiovascular disorders. Also, endothelial dysfunction plays an essential role in the development of atherosclerosis. We aimed to evaluate the effects of thyroid-stimulating hormone (TSH) on pro-inflammatory tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), angiogenic vascular endothelial growth factor (VEGF) and leukocyte adhesion, intercellular adhesion molecule 1 (ICAM-1) and E-selectin in human umbilical vein endothelial cells (HUVECs). In this study, HUVEC cells were treated with 1 and 2 μM of TSH in different treatment times. The gene and protein expression of ICAM-1, VEGF, and E-selectin were performed by real-time polymerase chain reaction and western blotting, respectively. Likewise, TNF-α and IL-6 protein levels were determined by the ELISA method. VEGF, ICAM-1, and E-selectin as endothelial dysfunction markers and also, TNF-α and IL-6 as pro-inflammatory cytokines were detectable in HUVEC. Besides, the results of this study revealed that TSH treatment down-regulates TNF-α and IL-6. Evaluating the gene and protein expression data revealed the upregulation of ICAM-1, E-selectin, and VEGF in TSH treated cases in different periods of exposure. Considering the multiple actions of TSH, it could be concluded that TSH plays a controversial role in atherogenesis by anti-inflammatory effects and on the other side, angiogenesis and leukocyte adhesion induction which is related to vascular cell proliferation.

Lack of associations between thyroid function and obstructive sleep apnea severity in adults with prediabetes and diabetes mellitus

PURPOSE

Hypothyroidism is associated with a high frequency of obstructive sleep apnea (OSA). However, the prevalence of OSA in hypothyroid patients is not different from the general population in many reports. The importance of thyroid function screening in sleep-disordered breathing is still controversial. This study aimed to explore the association between thyroid dysfunction and OSA in the adults with prediabetes or diabetes mellitus type 2, who have very high prevalence of OSA.

METHODS

OSA was assessed using an in-home monitoring device, WatchPAT200. OSA severity was measured using apnea-hypopnea index (AHI), oxygen desaturation index (ODI), minimum oxygen saturation (minO2), and time spent under oxygen saturation < 90% (T90). Patients with pre-existing thyroid dysfunction were excluded.

RESULTS

Participants included 70 men and 118 women with mean age 52.8 ± 10.9 years and body mass index 28.2 ± 4.9 kg/m². One hundred forty participants (75%) had OSA, with a median AHI of 10.1 (interquartile range 4.8, 18.3). The percentage of positive thyroid autoantibody (thyroperoxidase and thyroglobulin antibody) was similar among the subjects with and without OSA. There was no correlation between the levels of thyroid function (TSH, FT3, FT4, TSH/FT3, and TSH/FT4 ratio) and the severity indices of OSA (AHI, ODI, minO2, and T90).

CONCLUSIONS

These data do not support universal screening for thyroid dysfunction in OSA patients with diabetes or prediabetes.

Evaluation of growth hormone-releasing peptide-2 for diagnosis of thyrotropin-producing pituitary adenomas

Thyrotropin (TSH)-producing adenomas are a rare cause of hyperthyroidism and are a type of functional pituitary adenoma. The diagnosis of TSH-producing adenoma is a challenging problem in clinical endocrinology. Since growth hormone-releasing peptide-2 (GHRP-2) fails to induce TSH secretion in normal subjects, the effect of GHRP-2 on TSH levels was therefore examined in patients with TSH-producing adenomas. A total of 5 patients (4 women and 1 man) referred to our departments for further evaluation of pituitary hormones were followed-up using the GHRP-2, TSH-releasing hormone (TRH), octreotide, and bromocriptine tests to examine and evaluate TSH secretory dynamics in TSH-producing adenomas. Of 5 patients, 2 (40%) showed such a significant response, defined as a >50% increase in serum TSH level above baseline in the GHRP-2 test. Additionally, 1 patient showed a 48% increase in serum TSH level. In 1 patient whose adenoma was completely removed, basal serum concentrations of TSH were sufficiently suppressed after the operation, and serum TSH levels failed to increase in response to GHRP-2 administration. In 4 patients (80%), a poor response of serum TSH levels was observed in the TRH test. In 2 out of 5 patients (40%), serum TSH levels were significantly decreased following octreotide administration. No patient demonstrated a significant response to the bromocriptine test. In addition to TRH test, the GHRP-2 test as a potential diagnostic tool for TSH-producing pituitary adenomas.

2018 European Thyroid Association (ETA) Guidelines on the Diagnosis and Management of Central Hypothyroidism

OBJECTIVES

Central hypothyroidism (CeH) is a rare form of hypothyroidism characterized by insufficient thyroid stimulation due to disturbed pituitary and/or hypothalamic functioning. Due to its origin and the whole clinical context, CeH represents a challenging condition in clinical practice as it is characterized by suboptimal accuracy of clinical and biochemical parameters for diagnosis and management. Since no expert consensus or guidance for this condition is currently available, a task force of experts received the commitment from the European Thyroid Association (ETA) to prepare this document based on the principles of clinical evidence.

STUDY DESIGN

The task force started to work in February 2017 and after a careful selection of appropriate references (cohort studies, case reports, expert opinions), a preliminary presentation and live discussion during the 2017 ETA meeting, and several revision rounds, has prepared a list of recommendations to support the diagnosis and management of patients with CeH.

RESULTS

Due to the particular challenges of this rare condition in the different ages, the target users of this guidance are pediatric and adult endocrinologists. Experts agreed on the need to recognize and treat overt CeH at all ages, whereas treatment of milder forms may be dispensable in the elderly (> 75 years).

CONCLUSIONS

Despite the lack of randomized controlled clinical trials, the experts provide 34 recommendations supported by variable levels of strength that should improve the quality of life of the affected patients and reduce the metabolic and hormonal consequences of inadequate management.

[Relationship between thyrotropin and urine iodine in Han and Uygur nationalities pregnancy women in People's Hospital of Xinjiang Uygur Autonomous Region]

Objective: To investigate the relationship between thyrotropin (TSH) and urine iodine in pregnant women of Han and Uygur ethnic groups in People's Hospital of Xinjiang Uygur Autonomous Region. Methods: A total of 1 568 pregnant who completed screening of TSH and urine iodine in People's Hospital of Xinjiang Uygur Autonomous Region hospital from August 2014 to December 2017 were included in the study, 956 cases were Han and the other 612 were Uygur. Basic clinical data, serum TSH, thyroid peroxidase autoantibody (TPOAb) , and urine iodine levels were retrospectively analyzed. Results: (1) General results: The median urine iodine level was 162.6 μg/L (53.4-539.3 μg/L) , and the distribution of urine iodine classification was iodine deficiency 42.9% (672/1 568) , iodine appropriate 36.7% (576/1 568) , iodine slightly high 17.1% (268/1 568) and iodine excess 3.3% (52/1 568) respectively. (2) The median urine iodine levels of Han and Uygur pregnant women were 169.1 μg/L (54.6-583.4 μg/L) and 156.3 μg/L (53.1-539.3 μg/L) respectively, and the difference was statistically significant (P<0.05) .The distribution of urine iodine status in pregnancy between Han and Uygur was significantly different, which were 40.9% (391/956) vs. 45.9% (281/612) in iodine deficiency, 35.4% (338/956) vs. 38.9% (238/612) in iodine appropriate, 20.2% (193/956) vs. 12.3% (75/612) in iodine slightly high and 3.6% (34/956) vs. 2.9% (18/612) in iodine excess. (3) High serum TSH level proportion was significantly higher in Uygur ethnic group, early pregnancy, thyroid peroxidase antibody positive and anti-thyroglobulin antibody positive group when compared with Han, late pregnancy, thyroid peroxidase antibody negative and anti-thyroglobulin antibody negative groups (all P<0.05) . There were no significant differences in different age groups and iodine nutrition groups (P>0.05) . (4) There was no correlation between urinary iodine and TSH levels in all pregnant women (P>0.05) , neither in Han or Uygur group. When further stratified by gestational age, age, and antibody level, there was a positive correlation between urine iodine and serum TSH level in Han pregnant women >30 years old (P<0.05) , and there was a negative correlation in the third trimester in Uygur (P<0.05) . When serum antibody level, gestational week and age were controlled. There was no correlation between urine iodine and serum TSH level in neither group. Conclusions: (1) In Han and Uygur pregnant women, the median urine iodine level and the distribution of urine iodine classification between two ethnic groups are significantly different. (2) The correlation between urine iodine and serum TSH is not identified in Han or Uygur pregnant women.

Forever young: Endocrinology of paedomorphosis in the Mexican axolotl (Ambystoma mexicanum)

The Mexican axolotl (Ambystoma mexicanum) is a salamander species that does not undergo metamorphosis, resulting in the retention of juvenile characteristics in the mature breeding stage (paedomorphosis). Here we review the endocrinological studies investigating the proximate cause of axolotl paedomorphosis with a focus on the hypothalamo-pituitary-thyroid (HPT) axis. It is well established that axolotl paedomorphosis is a consequence of low activity of the HPT axis. The pituitary hormone thyrotropin (TSH) is capable of inducing metamorphosis in the axolotl, which indicates that all processes and interactions in the HPT axis below the pituitary level are functional, but that TSH release is impaired. In metamorphosing species, TSH secretion is largely controlled by the hypothalamic neuropeptide corticotropin-releasing hormone (CRH), which seems to have lost its thyrotropic activity in the axolotl. However, preliminary experiments have not yet confirmed a role for faulty CRH signalling in axolotl paedomorphosis. Other hypothalamic factors and potential pituitary inhibitors need to be investigated to identify their roles in amphibian metamorphosis and axolotl paedomorphosis.

Levels of serum thyroxine, triidothyronine and thyrotropin in patients with acute myocardial infarction

Objective

To determine the levels of serum thyroxine (T3, T4), triiodothyronine and thyrotropin in patients with acute myocardial infarction (AMI).

Methods

It was an observational prospective study and 60 patients (both males and females) of AMI, (diagnosed by ECG & cardiac enzymes.) were included. Serum thyroid stimulating hormone (TSH), Free T3 and Free T4 were measured and relevant data was entered into a predesigned proforma.

Results

FT3 levels were below the reference range in 56.7% cases while both the FT4 and TSH values were found to be the lower limit of normal range. When the decrease in FT3 was correlated with the duration of illness, it was found that significant inverse correlation existed between FT3 value and the duration of illness and linear regression line was obtained. No such correlation existed between FT4 and TSH values.

Conclusion

Thyroid hormone levels (FT3) decreases in AMI and this change is associated with the duration of illness.

Effect of iodinated contrast medium on thyroid function: a study in children undergoing cardiac computed tomography

BACKGROUND

Few studies, and with conflicting results, have evaluated the potential effects of iodinated contrast media on children's thyroid function.

OBJECTIVE

To investigate the effects of iodinated contrast medium on thyroid function in neonates, infants and young children with congenital heart disease undergoing cardiac computed tomography (CT).

MATERIALS AND METHODS

We retrospectively evaluated 10 neonates (group 1) and 23 infants and young children (group 2) without thyroid or renal disease for serum levels of thyroid-stimulating hormone, free triiodothyronine and free thyroxine before contrast-enhanced cardiac CT, 48 h after CT and at discharge from the hospital. Cardiac CT was performed with intravenous administration of 1.14±0.17 mL/kg of body weight of iopromide (containing 370 mg of iodine/mL).

RESULTS

Group 1 had a reduction of thyroid-stimulating hormone from baseline to 48 h post injection (P=0.002). Group 2 had a reduction of thyroid-stimulating hormone median levels from baseline to 48 h post injection and an increase from 48 h to discharge (P=0.0005 and P=0.0001, respectively).

CONCLUSION

Intravenous iodinated contrast medium in children with congenital heart disease caused transient thyroid-stimulating hormone decrease 48 h after CT, with thyroid-stimulating hormone returning to normal range at discharge.

Breast Milk Iodine Concentration Rather than Maternal Urinary Iodine Is a Reliable Indicator for Monitoring Iodine Status of Breastfed Neonates

There is no scientific consensus on whether breast milk iodine concentration (BMIC) accurately reflects iodine status in lactating mothers and breastfed infants. This study aimed to compare BMIC and maternal urinary iodine concentration (UIC) as indicators of iodine status in breastfed neonates. In this cross-sectional study, 147 lactating mothers and their neonates (3-5 days postpartum) were randomly selected from health care centers. Breast milk and urine samples were collected from each mother and neonate, and a heel-prick blood sample was taken from all neonates as part of a congenital hypothyroidism screening program. According to the World Health Organization criteria, median urinary iodine concentration (UIC) ≥ 100 μg/L in lactating mothers and neonates indicates iodine sufficiency. In areas of iodine sufficiency, median BMIC ≥ 100 μg/L is considered an adequate level. Overall, 129 (89.0%) and 16 (11.0%) mothers had BMICs ≥ 100 and ˂ 100 μg/L, respectively. Median (interquartile range [IQR]) maternal UIC was 70 μg/L (42-144 μg/L) and 37 μg/L (25-100 μg/L) in mothers with breast milk iodine levels ≥ 100 and ˂ 100 μg/L, respectively (P = 0.047); values for UIC of neonates born to mothers with BMICs ≥ 100 and ˂ 100 μg/L were 230 μg/L (114-310 μg/L) and 76 μg/L (41-140 μg/L), respectively (P < 0.001). In the linear regression model, neonate UIC was positively associated with BMIC in both unadjusted (β = 0.558, P < 0.001) and adjusted analysis (β = 0.541, P < 0.001). A similar result was found in logistic regression analysis, indicating that neonates born to mothers with BMIC ≥ 100 μg/L were more likely to have UIC ≥ 100 μg/L compared to those whose mothers had BMIC < 100 μg/L in both unadjusted (OR = 7.93, P < 0.001) and adjusted analysis (OR = 7.29, P = 0.001). The present findings indicate that BMIC is a more sensitive indicator than maternal UIC for assessment of iodine status in breastfed neonates. To address low levels of maternal UIC, further studies on the prescription of supplements containing 150 μg/day iodine during lactation period are warranted.

TSH ratio as a novel diagnostic method for Cushing's syndrome

Circadian variations impact thyrotropin (TSH) secretion; in Cushing's syndrome (CS) patients, the nocturnal serum TSH surge is abolished. The aim of this prospective study is to examine whether serum TSH surge may be a useful diagnostic method for CS. This prospective study recruited 136 inpatients for differential diagnosis of CS or subclinical CS (SCS), and 21 inpatients with depression at Osaka University Hospital. Serum TSH surge was assessed by the midnight-to-morning serum TSH ratio (2300-2400 h to 0800-0900 h). The diagnostic accuracy (sensitivity and specificity) between TSH ratio and ordinary screening tests [low-dose dexamethasone suppression test (LDDST), late-night serum cortisol and urine free cortisol (UFC)] were compared. Twenty-two patients were diagnosed as CS (12 overt CS and 10 SCS) and the remaining 120 patients were excluded for CS. The diagnostic accuracy of TSH ratio (cutoff value 1.0) yielded sensitivity 90.9% [95% confidence interval (CI) 70.8-98.9], specificity 95.0% (95% CI 89.4-98.1), and a high positive and low negative likelihood ratio [18.2 (95% CI 8.2-40.1) and 0.096 (95% CI 0.026-0.359), respectively]. The specificity of TSH ratio was significantly higher than LDDST and midnight serum cortisol test. The sensitivity of TSH ratio was significantly higher than UFC. TSH ratio showed more than 1.0 in all patients with depression and CYP3A4 inducer users. TSH ratio is a novel supportive diagnostic method with higher specificity than the current diagnostic methods for CS.

Relationship between serum thyrotropin and urine albumin excretion in euthyroid subjects with diabetes

BACKGROUND

Microalbuminuria represents vascular and endothelial dysfunction. Thyroid hormones can influence urine albumin excretion as it exerts crucial effects on the kidney and on the vascular system. This study explores the relationship between serum thyrotropin and urine albumin excretion in euthyroid patients with diabetes.

METHODS

A total of 433 patients with type 1 or 2 diabetes were included in this retrospective cross-sectional study. Data included anthropometric measurements and biochemical parameters from diabetes clinic. Males with urine albumin creatinine ratio >2.5 and female's >3.5 mg/mmoL were considered to have microalbuminuria.

RESULTS

34.9% of the patients had microalbuminuria. Prevalence of microalbuminuria increased according to TSH quartiles (26.9, 34.6, 38.5 and 44.9%, P for trend = 0.02). In a fully adjusted logistic regression model, higher TSH concentrations were associated with high prevalence of microalbuminuria (adjusted odds ratio 2.06 [95% CI: 1.14-3.72]; P = 0.02), while comparing the highest with the lowest quartile of TSH. Multiple linear regression analysis showed an independent association between serum TSH and urine albumin creatinine ratio (β = 0.007, t = 2.03 and P = 0.04). The risk of having microalbuminuria was higher with rise in TSH concentration in patients with younger age (<65 years), raised body mass index (≥25 kg/m²), hypertension, type 2 diabetes and hyperlipidaemia and age was the most important determinant ( P for interaction = 0.02).

CONCLUSION

Serum TSH even in the euthyroid range was positively associated with microalbuminuria in euthyroid patients with diabetes independent of traditional risk factors. This relationship was strongest in patients with components of the metabolic syndrome.

Low serum free thyroxine level is correlated with lipid profile in depressive patients with suicide attempt

The present research was carried out to observe the relationships between serum free triiothyronine (FT3), free thyroxine (FT4), thyroid-stimulating hormone (TSH) levels and lipid profile and suicide risk in depressive subjects. Serum concentrations of albumin, total bilrubin, uric acid, total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL), low-density lipoprotein cholesterol (LDL), high-sensitivity C-reactive protein (hs-CRP), FT3, FT4 and TSH were measured in 271 patients meeting the DSM-IV criteria for major depressive disorder (202 subjects without suicidal behavior and 69 suicide attempters). A significant decrease in serum TC, TG and FT4 levels was found in suicide attempters with major depressive disorder compared with non-suicide attempters (all p < 0.0025). For the other biochemical factors levels (albumin, total bilrubin, uric acid, HDL, LDL, hs-CRP, FT3, and TSH), there were no significant differences between suicide attempters and non-suicide attempters. Relativity analysis suggested that FT4 is positively and significantly correlated with TC (p < 0.0025); TSH is positively associated with HDL (p < 0.0025). Univariate analysis showed that serum TC and FT4 abundances are correlated with the suicide attempts in major depressive subjects. This research demonstrated that the levels of serum TC, TG, and FT4 levels in suicidal patients were greatly decreased compared with patients without suicidal behavior. These findings support the hypothesis that low serum FT4 level affects lipid profile in major depressive patients with suicidal attempt.

Reference intervals for thyrotropin in an area of Northern Italy: the Pordenone thyroid study (TRIPP)

PURPOSE

Thyrotropin (TSH) is the most accurate marker of thyroid dysfunction in the absence of pituitary or hypothalamic disease. Studies on TSH reference intervals (RIs) showed wide inter-individual variability and prompted an intense debate about the best estimation of TSH RIs.

DESIGN

We performed a population study on TSH RIs, using current data stored in the laboratory information system (LIS), at the Hospital Department of Laboratory Medicine, Pordenone (Italy), historically an area of mild-moderate iodine deficiency with a relatively high goiter prevalence.

METHODS

136,650 individuals constituted the final sample. A TSH immunoassay was performed on fasting serum samples with the Dimension Vista 1500 analyzer (Siemens Healthineers). We adopted the Kairisto's procedure to analyze TSH data downloaded by the LIS, applying the indirect strategy for deriving RIs.

RESULTS

TSH RIs of the entire population were 0.32-3.36 mIU/L with a distribution skewed towards higher values. RIs were 0.26-3.61 mIU/L for females, and 0.32-3.01 mIU/L for males. Unlike other studies, TSH median levels progressively decreased from 0-4 to 85-104 years in the overall population, both in male and in female subgroups, showing an inverse correlation between TSH and age in all groups.

CONCLUSIONS

This study is the first to analyze a high percentage (40%) of individuals from an ethnically homogenous Caucasian population. The results obtained emphasize the opportunity to define the TSH RIs according to age, gender and race, in addition to assay methods, and provide further insight about the possible role of iodine status.

High-normal serum thyrotropin levels and increased glycemic variability in type 2 diabetic patients

PURPOSE

High-normal thyrotropin (TSH) is related to reduced insulin sensitivity and may contribute to glycemic disorders in diabetes. We investigated the relationship between normal serum TSH levels and glycemic variability in euthyroid type 2 diabetic patients.

METHODS

A total of 432 newly diagnosed type 2 diabetic patients with euthyroid function and normal serum TSH levels were recruited between March 2013 and February 2017. Insulin sensitivity was evaluated by the Matsuda index (ISI_Matsuda) following a 75-g oral glucose tolerance test. Multiple glycemic variability indices, including the mean amplitude of glycemic excursions (MAGE), mean of daily differences (MODD), and standard deviation of glucose (SD), were calculated from glucose data obtained with a continuous glucose monitoring system. Average glucose accessed by 24-h mean glucose (24-h MG) was also calculated.

RESULTS

A normal serum TSH level was positively correlated with MAGE, MODD, SD, and 24-h MG (r = 0.206, 0.178, 0.186, and 0.132, respectively, p < 0.01). After adjusting for somatometric parameters, lipid profiles, ISI_Matsuda, and HbA1c via multiple linear regression analysis, mean differences [B(95% CI)] in MAGE, MODD, SD, and 24-h MG between the patients in the lowest and highest quartiles of TSH levels were 0.128(0.031, 0.226), 0.085(0.022, 0.148), 0.039(0.001, 0.078), and 0.002(-0.264, 0.267) mmol/L, respectively. High-normal TSH was independently associated with MAGE, MODD, and SD, but not 24-h MG.

CONCLUSIONS

High-normal serum TSH is a significant additional risk factor for increased glycemic variability in type 2 diabetic patients.

[Hypothyroidism-when and how to treat?]

The diagnosis of hypothyroidism is primarily based on clinical signs and symptoms as well as measurement of thyroid-stimulating hormone (TSH) concentration. Subclinical hypothyroidism is characterized by elevated TSH with normal serum free thyroxine (fT₄) and triiodothyronine (fT₃) levels, while in manifest hypothyroidism serum fT₄ and fT₃ levels are reduced. Common causes of primary hypothyroidism are autoimmune thyroiditis as well as therapeutic interventions, such as thyroid surgery or radioiodine therapy. Signs and symptoms of hypothyroidism include fatigue, bradycardia, constipation and cold intolerance. In subclinical hypothyroidism, symptoms may be absent. Initiation of levothyroxine (T₄) therapy not only depends on the level of TSH elevation, but also on other factors, such as patient age, presence of pregnancy or comorbidities. Treatment of patients with subclinical hypothyroidism is still a controversial topic. In general, thyroid hormone replacement therapy in non-pregnant adults ≤ 70 years is clearly indicated if the TSH concentration is >10 mU/l. Standard of care for treatment of hypothyroidism is T₄ monotherapy. The biochemical treatment goal for T₄ replacement in primary hypothyroidism is a TSH level within the reference range (0.4-4.0 mU/l). In contrast, in secondary hypothyroidism, serum fT₄ levels are the basis for adjusting thyroid hormone dosage. Inadequate replacement of T₄ resulting in subclinical or even manifest hyperthyroidism should urgently be avoided. T₄/liothyronine (T3) combination therapy is still a matter of debate and not recommended as standard therapy, but may be considered in patients with persistence of symptoms, despite optimal T₄ treatment, based on expert opinion.

[Influence of gender, age and season on thyroid hormone reference interval]

Objective: Using clinical "big data" , to investigate the factors that affect the levels of thyroid hormones, and to explore the partitioning criteria for reference intervals (RI) of these hormones. Methods: An observation study was conducted. Information of 107 107 individuals undergoing routine physical examination in Peking Union Medical College Hospital from September 1(st,) 2013 to August 31(st,) 2016 was collected, thyroid hormone of these subjects were detected. To explore the test results distribution and differences of TSH, FT4 and FT3 by gender and age; according to the seasonal division standard of China Meteorological Administration, the study period was divided into four seasons, and the seasonal fluctuation on TSH was analyzed.To define the appropriate partition by gender, age and season according to significant difference analysis. Results: In male and female, the distributions of TSH were 1.779(0.578-4.758), 2.023(0.420-5.343)mU/L, respectively, and the level of TSH in female was higher than in male (Z=-37.600, P<0.001). The distributions of FT4 were 0.127(0.098-0.162), 0.117(0.091-0.151) μg/L, the distributions of FT3 were 3.33(2.47-3.74), 3.01(2.35-3.57)ng/L. And the level of FT4, FT3 in female were significantly lower than in male (Z=-94.000, -154.600, all P<0.001). Furthermore, males were divided into two groups by 65 years old and female were divided by 50 years old, respectively, and the distributions of TSH in male and female of older group were 1.818(0.528-5.240), 2.111(0.348-5.735)mU/L, in younger group were 1.778(0.582-4.696), 1.991(0.427-5.316)mU/L. The level of TSH in older group was significantly higher than in younger group (Z=-2.269, -10.400, all P<0.05), and the distribution of TSH in older group was much wider than in younger. The distribution of whole in spring, summer and autumn was 1.869( 0.510-5.042)mU/L, in winter was 1.978(0.527-5.250) mU/L, and the difference between them had statistical significance (Z=-15.000, P<0.001). Conclusions: Gender and age significantly affect the serum levels of TSH, FT4, and FT3, the distribution of TSH in female and elder group are wider than in male, and that of FT4, FT3 are lower.Seasons significantly affect the serum TSH level, the peak value is observed in winter. There are obviously differences between "rough" RIs and manufacture recommended RIs. Each laboratory should establish reference intervals for thyroid hormones on the premise of appropriate grouping.

[Clinical analysis of the specific reference intervals of thyroid index for normal pregnant women]

Objective: To explore the reference intervals of thyrotropin (TSH) and free thyroxine (FT(4)) in normal pregnant women. Methods: Prospective and longitudinal sequential collection of the cases were performed. A total of 155 singleton pregnant women who had regular prenatal examination and delivery in West China Second Hospital of Sichuan University from January 2015 to December 2015 were included as the research group. Blood samples were sequentially collected from the pregnant women at the first (9-13(+6) weeks) , the second (24-27(+6) weeks) , the third (32-36 weeks) trimesters, respectively. Another 155 non-pregnant women were selected as the control group simultaneously, in an effort to establish a range of reference intervals of thyroid index in each period of pregnancy. Meanwhile, neonatal plantar blood were also collected on special filter paper and TSH levels were measured. Results: (1) TSH reference intervals [percentile 2.5-percentile 97.5 (P(2.5)-P(97.5)) ] were 0.08-3.29 mU/L, 0.59-4.22 mU/L and 0.81-4.33 mU/L in three trimesters respectively. FT(4) reference intervals were 11.88-20.06 pmol/L, 9.89-15.80 pmol/L and 9.22-15.77 pmol/L in three trimesters respectively. (2) The median serum TSH in the first trimester (1.35 mU/L) was lower than that in the second trimester (2.15 mU/L) , the third trimester (2.19 mU/L) , and the control group (2.19 mU/L) . The differences were all statistically significant (P<0.05) . There was no significant difference in median serum TSH between the second trimester and the third trimester, the second trimester and the control group, and the third trimester versus the control group. (3) The median serum FT(4) in the first trimester (15.16 pmol/L) was higher than that in the second trimester (12.39 pmol/L) and the third trimester (12.26 pmol/L) . The differences were both statistically significant (P<0.05) . The median FT(4) in the second trimester and the third trimester was lower than that in the control group (15.64 pmol/L) , and the differences were both statistically significant (P<0.05) . (4) In the first trimester, the median serum total triiodothyronine (TT(3)) level (2.32 nmol/L) was higher than that in the control group (1.56 nmol/L) , total thyroxine (TT(4)) level (154.60 nmol/L) was also higher than that in the control group (98.25 nmol/L) , and free triiodothyronine (FT(3)) level (4.70 pmol/L) was lower than that in the control group (4.84 pmol/L) , the differences were all statistically significant (P<0.05) . (5) The TSH levels of all neonatus were normal [ (2.1±1.3) mU/L]. Conclusions: The thyroid hormone levels between pregnant women and non-pregnant women are significantly different. Moreover, the reference intervals are vary with pregnancy period. It is important to establish the specific reference intervals of thyroid hormones in the first, second and third trimester of pregnancy specific to local region or unit.

Serum Thyroid Hormone and Thyrotropin Concentrations in Adult Horses as They Age

With more horses remaining active longer in life, it is important to characterize changes that occur normally with aging, so that these can be differentiated from development of disease. The objective of the study was to test the hypotheses that geriatric horses have lower circulating concentrations of thyroid hormones and/or higher serum thyrotropin (TSH) concentrations compared to younger horses. Serum thyroid hormone and TSH concentrations from 71 normal, healthy horses that had participated in prior research projects were analyzed for effects of age, sex, and season when samples were obtained. All samples had been assayed in the same previously validated radioimmunoassays. There were no differences in serum concentrations of thyroid hormones or TSH by sex or season. Serum total thyroxine (T4) was greater in 3- to 6-year-old horses compared to all other age groups and was negatively correlated with age. There were no differences among age groups for free T4 and total and free tri-iodothyronine (T3). Serum TSH concentration was significantly greater in old horses (≥15 or ≥20 years) compared to young (3-10 years) and intermediate (11-14 years) age groups. Serum TSH was positively correlated with age. There were no significant differences in thyroid hormone responses to thyrotropin releasing hormone (TRH) among young, intermediate, or old horses. However, the TSH response to TRH was significantly different in both groups of older horses compared to intermediate and young horses. Serum total thyroxine concentrations decrease and serum TSH concentrations increase in horses as they age, with no changes in free T4 or T3.

High Serum Thyrotropin Concentrations within the Reference Range: A Predictor of Malignancy in Nodular Thyroid Disease

OBJECTIVE

This study assessed whether or not a simple biochemical parameter, serum thyrotropin (TSH), within the reference range can predict the likelihood of thyroid malignancy in subjects undergoing fine-needle aspiration biopsy (FNAB) for thyroid nodules.

SUBJECTS AND METHODS

This cross-sectional study evaluated 236 patients without overt thyroid dysfunction who were not on levothyroxine therapy. They underwent FNAB of the thyroid nodules at the Clementino Fraga Filho University Hospital between 2011 and 2012. The reference range and serum TSH quartiles were determined according to age-specific values for serum TSH and then compared between the cases with benign thyroid nodular disease and differentiated thyroid carcinoma (DTC) based on surgical pathology reports.

RESULTS

Of the 236 patients, 201 (85.1%) underwent a surgical procedure (thyroidectomy) and 89/236 (44.3%) had DTC. The mean TSH concentrations were 2.09 ± 1.15 mU/L in benign patients versus 2.73 ± 1.33 mU/L in cases of DTC (p < 0.01). As TSH increased from quartiles 1 to 4, the frequency of a malignant diagnosis also increased progressively from 22% in quartile 1 to 65% in the last quartile (p ≤ 0.001).

CONCLUSION

Thyrotropin levels were positively associated with the diagnosis of DTC in thyroid nodules.

Signaling pathways to and from the hypophysial pars tuberalis, an important center for the control of seasonal rhythms

Seasonal (circannual) rhythms play an important role for the control of body functions (reproduction, metabolism, immune responses) in nearly all living organisms. Also humans are affected by the seasons with regard to immune responses and mental functions, the seasonal affective disorder being one of the most prominent examples. The hypophysial pars tuberalis (PT), an important interface between the hypophysial pars distalis and neuroendocrine centers in the brain, plays an essential role in the regulation of seasonal functions and may even be the seat of the circannual clock. Photoperiodic signals provide a major input to the PT. While the perception of these signals involves extraocular photoreceptors in non-mammalian species (birds, fish), mammals perceive photoperiodic signals exclusively in the retina. A multisynaptic pathway connects the retina with the pineal organ where photoperiodic signals are translated into the neurohormone melatonin that is rhythmically produced night by night and encodes the length of the night. Melatonin controls the functional activity of the mammalian PT by acting upon MT1 melatonin receptors. The PT sends its output signals via retrograde and anterograde pathways. The retrograde pathway targetting the hypothalamus employs TSH as messenger and controls a local hypothalamic T3 system. As discovered in Japanese quail, TSH triggers molecular cascades mediating thyroid hormone conversion in the ependymal cell layer of the infundibular recess of the third ventricle. The local accumulation of T₃ in the mediobasal hypothalamus (MBH) appears to activate the gonadal axis by affecting the neuro-glial interaction between GnRH terminals and tanycytes in the median eminence. This retrograde pathway is conserved in photoperiodic mammals (sheep and hamsters), and even in non-photoperiodic laboratory mice provided that they are capable to synthesize melatonin. The anterograde pathway is implicated in the control of prolactin secretion, targets cells in the PD and supposedly employs small molecules as signal substances collectively denominated as "tuberalins". Several "tuberalin" candidates have been proposed, such as tachykinins, the secretory protein TAFA and endocannabinoids (EC). The PT-intrinsic EC system was first demonstrated in Syrian hamsters and shown to respond to photoperiodic changes. Subsequently, the EC system was also demonstrated in the PT of mice, rats and humans. To date, 2-arachidonoylglycerol (2-AG) appears as the most important endocannabinoid from the PT. Likely targets for the EC are folliculo-stellate cells that contain the CB1 receptor and appear to contact lactotroph cells. The CB1 receptor was also found on corticotroph cells which appear as a further target of the EC. Recently, the CB1 receptor was also localized to CRF-containing nerve fibers running in the outer zone of the median eminence. This finding suggests that the EC system of the PT contributes not only to the anterograde, but also to the retrograde pathway. Taken together, the results support the concept that the PT transmits its signals via a "cocktail" of messenger molecules which operate also in other brain areas and systems rather than through PT-specific "tuberalins". Furthermore, they may attribute a novel function to the PT, namely the modulation of the stress response and immune functions.