Mean FT3 Concentrations Research Articles

Thyroid function tests in healthy kittens aged between 2 and 16 weeks.

This study aimed to determine thyroid hormone concentrations in a cohort of healthy kittens due to the paucity of information in the literature, and the potential for congenital hypothyroidism (CH) to contribute to fading kitten syndrome (FKS). The serum concentrations of total thyroxine (TT4), free thyroxine (fT4), total triiodothyronine (TT3), free triiodothyronine (fT3) and thyroid-stimulating hormone (TSH) were measured in 19 healthy kittens aged 2-16 weeks. Mean TT4, fT4, TT3 and fT3 concentrations significantly differed across age groups. Mean TT4 and fT4 concentrations peaked at 6 and 5 weeks of age, respectively. The TT4 concentration exceeded the adult cat reference interval (ACRI) in 54% (32/59) of samples at week 6, with the highest TT4 concentration being 7.1 µg/dl (91 nmol/l). Mean TT3 and fT3 concentrations also peaked at 6 weeks of age. Mean TT3 concentration started below the ACRI until 4 weeks of age, after which it remained within the ACRI. The mean fT3 concentration was within the ACRI at all ages. The mean TSH concentration did not differ across age groups and remained within the ACRI in nearly 100% of samples. Peak TT4, fT4, TT3 and fT3 concentrations in healthy kittens at 5 and 6 weeks of age are likely due to changes in the maternal transfer of thyroid hormones after weaning and organ system development. Knowing healthy neonatal and pediatric thyroid hormone concentrations in a cohort of kittens might help a veterinarian interpret thyroid hormone levels when trying to rule out CH in a kitten with FKS.

Thyroid axis function after in-patient treatment of acute psychosis with antipsychotics: a naturalistic study.

BackgroundEndocrine function in psychiatric patients may be affected by mental disorder itself as well as by antipsychotic medications.The aim of this naturalistic observational study was to determine if treatment of acute psychotic episode with antipsychotic medication affects thyroid axis hormone concentrations and if such changes are associated with symptomatic improvement.MethodsEighty six adult acute psychotic patients, consecutively admitted to a mental hospital, were recruited for the study. All patients were physically healthy and without thyroid disease. During the hospitalization period all study patients received treatment with antipsychotic medication according to clinical need. Severity of the psychotic episode was evaluated using the Brief Psychiatric Rating Scale (BPRS) and venous blood samples were drawn for analysis of free triiodothyronine (FT3), free thyroxine (FT4), and thyroid stimulating hormone (TSH) concentrations on the day of admission and on the day of discharge from the hospital.ResultsAntipsychotic drug treatment was associated with decrease of mean FT3 (p < 0.001) and FT4 (p = 0.002) concentrations; and with increase of mean TSH (p = 0.016) concentrations. Changes in thyroid hormone concentrations were mostly predicted by baseline hormone concentrations. Individual changes were not limited to decrease in high hormone concentrations; in patients who had low FT3 or FT4 concentrations, treatment resulted in increase in concentrations. Such an increase was established in one-quarter of patients for FT3 concentrations and in one-third of patients for FT4 concentrations. Fall in FT4 concentrations negatively correlated with the improvement in the BPRS score (r = −0.235, p = 0.023).ConclusionsThe study indicates that antipsychotic treatment resulted in a decrease in mean FT3 concentrations and in an increase in mean TSH concentrations after recovery from acute psychosis. Symptomatic improvement was less evident in patients who experienced a decrease in FT4 concentrations.Trial registrationEudraCT No.2007-001541-18

Thyroid Function from Birth to Adolescence in Prader-Willi Syndrome

To describe the response of thyroid-stimulating hormone (TSH) to thyroid-releasing hormone in children and adolescents with Prader-Willi syndrome (PWS), and to compare TSH and total thyroxine (TT4) concentrations measured on neonatal screening for congenital hypothyroidism in children with PWS and controls. All participants had genetically confirmed PWS. The TSH responses to thyroid-releasing hormone, free thyroxine (fT4), and free triiodothyronine (fT3) were measured in 21 subjects (14 females and 7 males; mean age, 6.4 years). Capillary TT4 was measured on neonatal screening samples from 23 subjects with PWS (14 females and 9 males), each of whom was matched for birth weight and sex with 4 anonymized controls. One subject with PWS had tertiary hypothyroidism. TSH level increased from 1.37 mU/L at baseline to 39.6 mU/L at 20 minutes, 47.2 mU/L at 40 minutes, 44.5 mU/L at 60 minutes, and 47.2 mU/L at 120 minutes. fT4 concentration was 6.3 pmol/L, and fT3 concentration was 4.6 pmol/L. In the other 20 subjects, mean TSH level was 1.9 mU/L (range, 0.8-4.2 mU/L) at baseline and 21.8 mU/L (range, 10.0-46.7 mU/L) at 20 minutes (peak). Mean fT4 concentration (10.4 pmol/L; range, 8.2-13.5 pmol/L) was in the lower one-third of the normal range in 18 subjects, and mean fT3 concentration (6.1 pmol/L; range, 4.8-8.4 pmol/L) was above the median in 13 subjects. In neonates, mean TSH level was 3.1 mU/L (range, 0.4-10.0 mU/L) in subjects with PWS versus 3.3mU/L (range, 0.0-7.0 mU/L) in controls, and mean TT4 in subjects with PWS was 111% (range, 17%-203%) that of controls (P = not significant). Thyroid function was normal in our newborn subjects. In older children, frank hypothyroidism was found in only 1 of our 21 subjects. Thus, levothyroxine treatment should not be routinely prescribed to youth with PWS.

The influence of liver and pancreas surgery on the thyroid function

BackgroundNowadays, the increasing number of oncologic patients with liver or pancreatic tumours are subjected to surgical treatment, as it can provide a long-term survival or sometimes cure. As a result, numerous new clinical questions regarding metabolic disturbances in these patients have been arisen. Among others, the impact of the pancreas and liver surgery extent in relation to the thyroid function remains to be elucidated.Materials and methodsThe study comprised 51 patients (25 men and 26 women, mean age ± SD 61.6 ± 10.4 yrs, mean ± SD) with pancreatic or liver tumours, qualified for abdominal operation. Serum levels of FT3, FT4 and TSH were measured on the day before (time “0”) and on the 1st, 3rd and 5th day after surgery in two (2) subgroups reflecting the extent of surgery: twenty seven (27) patients (14 men and 13 women, mean age ± SD 61.5 ± 11.8 yrs) after major surgery (Whipple’s surgery, right and left hemihepatectomy, segmentectomy of the liver, distal pancreatectomy, total duodenopancreatectomy) and twenty four (24) patients (11 men and 13 women, mean age ± SD 61.8 ± 8.9 yrs) after minor, palliative surgery (exploratory laparotomy, gastroenterostomy, triple by-pass, liver tumour embolization, hepaticojejunostomy). Additionally, the obtained results were analyzed in relation to the type of the disease (pancreatic surgery vs liver surgery).ResultsMean serum FT3 level decreased significantly during the study in major and minor surgery subgroups (p<0.001, in both) in comparison to the baseline values, accompanied by stable serum concentrations of TSH (NS) and FT4 (NS). The above decreasing tendency in FT3 concentrations was similar in both subgroups (NS), the same as were unchanged levels of TSH (NS) and FT4 (NS). Mean FT4 concentration on the 3rd and 5th day after major surgery was lower in pancreatic tumour patients in comparison to liver tumour patients (p=0.002, p=0.032, respectively). Similarly, mean FT3 concentration on the 3rd day in minor surgery subgroup was lower in pancreatic tumour patients in comparison to liver tumour patients (p=0.015).DiscussionOur findings have confirmed essential reduction of FT3 values after abdominal surgery, independently of surgery extent. Additionally, pancreatic tumour patients are more likely to have lower FT3 and FT4 levels after surgery when compared to liver tumour patients.

Effects of rehabilitation treatment on thyroid function

The aim of the study was to evaluate the effects of an intensive rehabilitation programme on thyroid metabolism, the relationship between disability and thyroid hormone level, and the occurrence of nonthyroidal illness syndrome (NTIS) before and after rehabilitation. This was a clinical prospective study. Orthopaedic surgery patients (n = 82) were classified into two groups: patients in whom early active mobilization and walking were possible (walking group, WG, n = 45), and patients in whom these were not recommended (nonwalking group, NWG, n = 37). Levels of free T3 (fT3), fT4, TSH and rT3 were measured before and after surgery, and then at 1, 3, 7, 14 and 30 days from the beginning of rehabilitation. Personal, nutritional and clinical data were acquired for all patients. The Barthel Index (BI) was used to assess disability before and after rehabilitation. Immediately after surgery, both groups of patients showed a significant decrease in mean fT3 concentrations and a significant increase in rT3; mean fT4 values decreased significantly only in NWG patients. Once rehabilitation had been completed, fT3 and rT3 levels returned to baseline values in WG patients. In NWG patients mean fT3 and fT4 levels continued to decrease significantly and rT3 values remained significantly high until the end of rehabilitation. NTIS occurred in 38% of the NWG patients. No significant changes in TSH levels were observed in either group. Finally, we observed a direct correlation between fT3 levels and the BI in WG patients. Our data suggest that early patient mobilization and physical activity during an active and intensive rehabilitation programme induce recovery of thyroid function and avoid occurrence of NTIS.

Pediatric reference intervals for thyroid hormone levels from birth to adulthood: a retrospective study

BackgroundAge- and sex-specific reference intervals are an important prerequisite for interpreting thyroid hormone measurements in children. However, only few studies have reported age- and sex-specific pediatric reference values for TSHbasal (TSH), free T3 (fT3), and free T4 (fT4) so far. Reference intervals are known to be method- and population-dependent. The aim of our study was to establish reference intervals for serum TSH, fT3, and fT4 from birth to 18 years and to assess sex differences.Methods2,194 thyroid hormone tests obtained from a hospital-based pediatric population were included into our retrospective analysis. Individuals with diagnoses or medications likely to affect thyroid function were primarily excluded, as well as the diagnostic groups, if different from the purely healthy subgroup (n = 414). Age groups were ranging from 1 day to 1 month, 1 – 12 months, and 1 – 5, 6 – 10, 11 – 14, and 15 – 18 years, respectively. Levels of fT3, fT4 and TSH were measured on Advia® Centaur™ automated immunoassay system.ResultsThe final sample size for reference data creation was 1,209 for TSH, 1,395 for fT3, and 1,229 for fT4. Median and 2.5/10/25/75/90/97.5 percentiles were calculated for each age group. Males had greater mean fT3 concentrations than females (p < 0.001). No sex-differences were found for TSH and fT4 between age-matched serum samples. Median concentrations of fT3, fT4 and TSH were greatest during the first month of life, followed by a continuous decline with age.ConclusionOur results corroborate those of previous studies showing that thyroid hormone levels change markedly during childhood, and that adult reference intervals are not universally applicable to children. Moreover, differences of our reference intervals compared to previous studies were observed, likely caused by different antibody characteristics of various analytical methods, different populations or undefined geographic covariates, e.g. iodine and selenium status.

Function, structure, and volume of thyroid gland following allogenic kidney transplantation

The aim of the study was to assess the structure, volume, and function of the thyroid gland following kidney transplantation compared with those features of long-term transplant recipients as well as patients with normal native kidney function. Study group A consisted of 30 patients undergoing allogenic kidney transplantation, study group B included 30 long-term kidney transplant recipients who displayed stable renal function at 4 to 11 years following transplantation; control group C comprised 38 patients who were diagnosed or treated for reasons other than thyroid or renal insufficiency. Mean FT-3 concentrations in group A decreased from 2.19 pg/mL preoperatively to 1.52 pg/mL on the first posttransplantation day, returning to the preoperative values (2.06 pg/mL) at 30 days postoperatively. After 6 months the concentrations of thyroid hormones were similar to those among the long-term posttransplantation group (group B), although still lower than those in the control group. Mean thyroid volume in dialyzed patients was 17.10 mL; in the long-term group, 17.60 mL; and in the control group, 15.82 mL between groups that were not statistically significant. Abnormal structure of the thyroid gland was observed in 63% of group A (n = 19), 70% of group B (n = 21), and 29% of the control group. Significantly more abnormal thyroid gland structures were observed among dialyzed or transplanted patients. The thyroid volume was similar in all groups. Significant transient decrease in thyroid stimulating hormone (TSH) and free triidothyronine (FT-3) was not free thyroxine (FT-4) concentrations following kidney transplantation. Occasionally, increase accompanied by a change in FT-4 and TSH concentrations were observed, and antithyroid antibodies were detected only sporadically.

Free triiodothyronine measured in dried blood spots from normal, low-birth-weight, and hypothyroid neonates.

Free triiodothyronine (FT3) has rarely been studied in neonates, primarily because of obvious problems in obtaining serum samples from neonates for research purposes. We adapted an analog radioimmunoassay for measuring FT3 in dried blood samples and used it to assay 361 samples selected from those collected for the screening for neonatal hypothyroidism. The mean FT3 concentration in healthy neonates on the fourth postpartum day is 2.55 pmol per liter of whole blood (SD 0.78 pmol/L, n = 145), the same as in healthy adults. Low-birth-weight infants have a decreased concentration of FT3, and this decrease is much greater in premature neonates than in infants at low weight for gestational age. In six hypothyroid newborns, the FT3 concentration was normal or increased, clearly indicating that FT3 assay is not a diagnostic tool for hypothyroidism. FT3 was barely detectable in one case of congenital galactosemia.

Serum free thyroid hormones in subclinical hypothyroidism.

Serum free thyroxine (FT4) and free triiodothyronine (FT3) concentrations were measured in a group of 52 patients with subclinical hypothyroidism (SH) and in an equal group of age and sex-matched normal controls. SH was defined by normal total T4 (TT4) and total T3 (TT3) concentrations, normal FT4 and FT3 indices, raised TSH levels, in the absence of signs and symptoms of hypothyroidism. Serum FT4 levels averaged 6.1 +/- 1.6 pg/ml (mean +/- SD, p less than 0.001 vs controls), with values below lower normal limits in 33/52 patients; mean FT3 concentrations averaged 3.1 +/- 0.7 pg/ml (p less than 0.001 vs controls), with values below lower normal limits in 8/52 patients. The analysis of results by the Galen and Gambino predictive value model demonstrated a higher sensitivity, but a lower specificity of FT4 as compared to FT3 in the diagnosis of SH. These results indicate that FT4 should be measured in addition to TSH for the diagnosis of impending thyroid failure, thus showing that in many cases patients with so-called subclinical hypothyroidism are actually already mild hypothyroid.

Determination of free triiodothyronine in serum: Comparison of radioimmunoassay with equilibrium dialysis method.

In normal volunteers, serum free triiodothyronine (FT3) concentrations determined by Immophase FT3 RIA kit, Amerlex FT3 RIA kit and equilibrium dialysis methods (absolute FT3, AFT3: product of total T3 and percent FT3) were 4.03 +/- 0.65, 3.69 +/- 0.58 and 3.22 +/- 0.65 pg/ml (mean +/- S.D.), respectively. The normal free triiodothyronine index (FT3I) was 38.4 +/- 6.5. In patients with hyper-and hypothyroidism, the FT3 values measured by these methods were clearly abnormal. In patients with decreased thyroxine binding-globulin, the mean FT3 concentrations determined by these methods were not significantly different from the normal. However, the mean FT3I was significantly lower than normal. In pregnant women at delivery, Amerlex FT3 values were subnormal in 7 of 9 subjects. All of these samples except one were within the normal range when evaluated by Immophase FT3 and AFT3, although their mean values were significantly lower than the mean of normal. On the other hand, the mean FT3I was not significantly different from the mean of normal. The correlations between FT3 were all statistically significant. In a clinically euthyroid patient who had chronic thyroiditis and who was shown to have anti-T3 antibody in her serum, Immophase FT3 and Amerlex FT3 values were above the high standards. However, AFT3, calculated by multiplying total T3 (determined after ethanol extraction) by percent FT3 was normal. In conclusion, the evaluation of FT3 by these radioimmunoassay methods proved clinically useful, when appropriate limitations are considered.