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Vermeulen A, Verdonck L, Kaufman JM. A critical evaluation of simple methods for the estimation of free testosterone in serum. J Clin Endocrinol Metab 1999; 84:3666-72. [PMID: 10523012 DOI: 10.1210/jcem.84.10.6079] [Citation(s) in RCA: 2345] [Impact Index Per Article: 90.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The free and nonspecifically bound plasma hormone levels generally reflect the clinical situation more accurately than total plasma hormone levels. Hence, it is important to have reliable indexes of these fractions. The apparent free testosterone (T) concentration obtained by equilibrium dialysis (AFTC) as well as the fraction of serum T not precipitated by 50% ammonium sulfate concentration (non-SHBG-T; SHBG, sex hormone-binding globulin), often referred to as bioavailable T, appear to represent reliable indexes of biologically readily available T, but are not well suited for clinical routine, being too time consuming. Several other parameters have been used without complete validation, however: direct immunoassay of free T with a labeled T analog (aFT), calculation of free T (FT) from total T and immunoassayed SHBG concentrations (iSHBG), and the free androgen index (FAI = the ratio 100T/iSHBG). In the view of substantial discrepancies in the literature concerning the free or bioavailable T levels, we compared AFTC, FT, aFT, FAI, and non-SHBG-T levels in a large number of sera with SHBG capacities varying from low, as in hirsute women, to extremely high as in hyperthyroidism. All these indexes of bioavailable T correlated significantly with the AFTC concentration; AFTC and FT values were almost identical under all conditions studied, except during pregnancy. Values for aFT, however, were only a fraction of either AFTC or FT, the fraction varying as a function of SHBG levels. Also, the FAI/AFTC ratio varied as a function of the SHBG levels, and hence, neither aFT nor FAI is a reliable index of bioavailable T. The FT value, obtained by calculation from T and SHBG as determined by immunoassay, appears to be a rapid, simple, and reliable index ofbioavailable T, comparable to AFTC and suitable for clinical routine, except in pregnancy. During pregnancy, estradiol occupies a substantial part of SHBG-binding sites, so that SHBG as determined by immunoassay overestimates the actual binding capacity, which in pregnancy sera results in calculated FT values that are lower than AFTC. The nonspecifically bound T, calculated from FT, correlated highly significantly with and was almost identical to the values of non-SHBG-T obtained by ammonium sulfate precipitation, testifying to the clinical value of FT calculated from iSHBG.
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Review |
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Abstract
Subclinical thyroid diseases--subclinical hyperthyroidism and subclinical hypothyroidism--are common clinical entities that encompass mild degrees of thyroid dysfunction. The clinical significance of mild thyroid overactivity and underactivity is uncertain, which has led to controversy over the appropriateness of diagnostic testing and possible treatment. In this Seminar, we discuss the definition, epidemiology, differential diagnoses, risks of progression to overt thyroid disease, potential effects on various health outcomes, and management of subclinical hyperthyroidism and subclinical hypothyroidism. Treatment recommendations are based on the degree to which thyroid-stimulating hormone concentrations have deviated from normal and underlying comorbidities. Large-scale randomised trials are urgently needed to inform how to best care for individuals with subclinical thyroid disease.
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Review |
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Smith FR, Goodman DS. The effects of diseases of the liver, thyroid, and kidneys on the transport of vitamin A in human plasma. J Clin Invest 1971; 50:2426-36. [PMID: 5096525 PMCID: PMC292185 DOI: 10.1172/jci106741] [Citation(s) in RCA: 325] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The effects of diseases of the liver, the thyroid, and the kidneys on the retinol-binding protein (RBP)-prealbumin (PA) system responsible for the transport of vitamin A in plasma were examined, using a radial gel diffusion immunoassay for PA and the previously described radioimmunoassay for RBP. Measurements were made on plasma samples from 118 normal subjects, 31 patients with cirrhosis, 5 with chronic active hepatitis, 27 with acute viral hepatitis, 14 patients with hyperthyroidism, 7 with hypothyroidism, and 26 patients with chronic renal disease of varying etiologies. In the patients with liver disease, the levels of vitamin A, RBP, and PA were all markedly decreased and were highly significantly correlated over a wide range of concentrations. Serial samples were available in 19 patients with acute hepatitis; as the disease improved the plasma concentrations of vitamin A, RBP, and PA all increased. In patients with acute hepatitis RBP concentrations correlated negatively with the levels of plasma bilirubin, glutamic-oxaloacetic transaminase, and alkaline phosphatase. In the hyperthyroid patients both RBP and PA concentrations were significantly lower than normal; in hypothyroidism, neither protein showed levels significantly different from normal. In both hyper- and hypothyroidism and in liver disease, the molar ratios of RBP:PA and of RBP:vitamin A were not significantly different from normal.Patients with chronic renal disease had marked abnormalities in the plasma concentrations of RBP and vitamin A and in the molar ratios examined. In renal disease the levels of both RBP and vitamin A were greatly elevated, while the PA levels remained normal. The molar ratios of RBP:PA and of RBP:vitamin A were both markedly elevated. In many patients RBP was present in molar excess as compared with PA. The presence of a relatively large proportion of free RBP, not complexed to PA, in some patients with chronic renal disease was confirmed by gel filtration. The free RBP, present in molar excess, was capable of forming a complex with additional purified PA added to the plasma. The kidneys appear to play an important role in the normal metabolism of RBP.
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Vermeulen A, Stoïca T, Verdonck L. The apparent free testosterone concentration, an index of androgenicity. J Clin Endocrinol Metab 1971; 33:759-67. [PMID: 5125384 DOI: 10.1210/jcem-33-5-759] [Citation(s) in RCA: 297] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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297 |
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Abstract
BACKGROUND Biochemical evidence of hyperthyroidism may be associated with low bone mass, particularly in older postmenopausal women, but no prospective studies of thyroid function and subsequent fracture risk have been done. OBJECTIVE To examine the association between low levels of thyroid-stimulating hormone (TSH) and fracture in older women. DESIGN Prospective cohort study with case-cohort sampling. SETTING Four clinical centers in the United States. PATIENTS 686 women older than 65 years of age from a cohort of 9704 women recruited from population-based listings between 1986 and 1988. MEASUREMENTS Baseline assessment of calcaneal bone mass, spine radiography, and history of thyroid disease. Spine radiography was repeated after a mean follow-up of 3.7 years; nonspine fractures were centrally adjudicated. Thyroid-stimulating hormone was measured in sera obtained at baseline from 148 women with new hip fractures, 149 women with new vertebral fractures, and a subsample of 398 women randomly selected from the cohort. RESULTS After adjustment for age, history of previous hyperthyroidism, self-rated health, and use of estrogen and thyroid hormone, women with a low TSH level (0.1 mU/L) had a threefold increased risk for hip fracture (relative hazard, 3.6 [95% CI, 1.0 to 12.9]) and a fourfold increased risk for vertebral fracture (odds ratio, 4.5 [CI, 1.3 to 15.6]) compared with women who had normal TSH levels (0.5 to 5.5 mU/L). After adjustment for TSH level, a history of hyperthyroidism was associated with a twofold increase in hip fracture (relative hazard, 2.2 [CI, 1.0 to 4.4]), but use of thyroid hormone itself was not associated with increased risk for hip fracture (relative hazard, 0.5 [CI, 0.2 to 1.3]). CONCLUSIONS Women older than 65 years of age who have low serum TSH levels, indicating physiologic hyperthyroidism, are at increased risk for new hip and vertebral fractures. Use of thyroid hormone itself does not increase risk for fracture if TSH levels are normal.
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Multicenter Study |
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Aoki Y, Belin RM, Clickner R, Jeffries R, Phillips L, Mahaffey KR. Serum TSH and total T4 in the United States population and their association with participant characteristics: National Health and Nutrition Examination Survey (NHANES 1999-2002). Thyroid 2007; 17:1211-23. [PMID: 18177256 DOI: 10.1089/thy.2006.0235] [Citation(s) in RCA: 263] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Describe thyrotropin (TSH) and thyroxine (T4) levels in the U.S. population and their association with selected participant characteristics. DESIGN Secondary analysis of data from the National Health and Nutrition Examination Survey (NHANES) collected from 4392 participants, reflecting 222 million individuals, during 1999-2002. RESULTS Hypothyroidism prevalence (TSH > 4.5 mIU/L) in the general population was 3.7%, and hyperthyroidism prevalence (TSH < 0.1 mIU/L) was 0.5%. Among women of reproductive age (12-49 years), hypothyroidism prevalence was 3.1%. Individuals aged 80 years and older had five times greater odds for hypothyroidism compared to 12- to 49-year-olds (adjusted odds ratio [OR] = 5.0, p = 0.0002). ORs were adjusted for sex, race, annual income, pregnancy status, and usage of thyroid-related medications (levothyroxine/thyroid, estrogen, androgen, lithium, and amiodarone). Compared to non-Hispanic whites, non-Hispanic blacks had a lower risk for hypothyroidism (OR = 0.46, p = 0.04) and a higher risk for hyperthyroidism (OR = 3.18, p = 0.0005), while Mexican Americans had the same risk as non-Hispanic whites for hypothyroidism, but a higher risk for hyperthyroidism (OR = 1.98, p = 0.04). Among those taking levothyroxine or desiccated thyroid, the adjusted risk for either hypothyroidism (OR = 4.0, p = 0.0001) or hyperthyroidism (OR = 11.4, p = 4 x 10(-9)) was elevated. CONCLUSIONS Associations with known factors such as age, race, and sex were confirmed using this data set. Understanding the prevalence of abnormal thyroid tests among reproductive-aged women informs decisions about screening in this population. The finding that individuals on thyroid hormone replacement medication often remain hypothyroid or become hyperthyroid underscores the importance of monitoring.
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Abstract
BACKGROUND Serum cystatin C (CysC) is a novel marker for kidney function that has been claimed to be superior to serum creatinine. Thyroid dysfunction may alter creatinine, which has been found to be increased in hypothyroidism and decreased in hyperthyroidism. This study was performed to evaluate whether changes in CysC and creatinine are parallel during the treatment of hypo- and hyperthyroidism, respectively. METHODS Prospective case series of 22 consecutively referred patients with thyroid dysfunction. Creatinine and CysC were determined at the time of diagnosis of hypo- and hyperthyroidism, and when free thyroxine (fT4) returned into the normal range. Hypothyroid patients were treated with levothyroxine. Hyperthyroid patients were treated with antithyroid drugs, surgery, or radioiodine. RESULTS Nine patients with hypothyroidism and 13 patients with hyperthyroidism were included. In patients with hypothyroidism mean fT4 (+/-SD) was 4.9 +/- 2.5 pmol/L (reference, 12 to 22) at diagnosis and increased to 16.6 +/- 3.6 pmol/L when patients were treated with levothyroxine. Creatinine decreased from 86 +/- 13 micromol/L (reference, 70 to 105) in the hypothyroid state to 76 +/- 16 micromol/L when fT4 normalized (P = 0.062), whereas CysC increased from 0.84 +/- 0.17 mg/L (reference, 0.63 to 1.33) to 1.1 +/- 0.28 mg/L (P < 0.001). In patients with hyperthyroidism, mean fT4 was 54.6 +/- 22.7 pmol/L (reference, 12 to 22) at diagnosis and decreased to 15.8 +/- 3.6 pmol/L following treatment with antithyroid drugs, thyroid surgery, or radioiodine. Creatinine increased from 67 +/- 15 micromol/L at diagnosis of hyperthyroidism to 75 +/- 9 micromol/L when fT4 normalized (P = 0.004), whereas CysC declined from 1.32 +/- 0.17 mg/L to 0.95 +/- 0.19 mg/L (P < 0.001). CONCLUSION Thyroid dysfunction has a major impact on CysC levels. Therefore, thyroid function has to be considered when CysC is used as a marker of kidney function. In contrast to creatinine concentrations, CysC levels are lower in the hypothyroid and higher in the hyperthyroid state as compared with the euthyroid state.
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Rosner W. A simplified method for the quantitative determination of testosterone-estradiol-binding globulin activity in human plasma. J Clin Endocrinol Metab 1972; 34:983-8. [PMID: 4112000 DOI: 10.1210/jcem-34-6-983] [Citation(s) in RCA: 260] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Bowers CY, Friesen HG, Hwang P, Guyda HJ, Folkers K. Prolactin and thyrotropin release in man by synthetic pyroglutamyl-histidyl-prolinamide. Biochem Biophys Res Commun 1971; 45:1033-41. [PMID: 5000704 DOI: 10.1016/0006-291x(71)90441-4] [Citation(s) in RCA: 256] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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Clinical Trial |
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256 |
12
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Van Herle AJ, Uller RP, Matthews NI, Brown J. Radioimmunoassay for measurement of thyroglobulin in human serum. J Clin Invest 1973; 52:1320-7. [PMID: 4739914 PMCID: PMC302394 DOI: 10.1172/jci107303] [Citation(s) in RCA: 242] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
A specific and reproducible double antibody radioimmunoassay for the measurement of thyroglobulin (HTg) in human serum has been developed. Since antithyroglobulin autoantibodies combine with the [(131)I] HTg tracer, antibody-positive sera were rejected for measurement. Specificity is demonstrated in that thyroid analogous such as thyroxine (T(4)), triiodothyronine (T(2)) monoiodotyrosine (MIT) and diiodotyrosine (DIT) did not crossreact. Sera previously reacted with anti-HTg-Sepharose contained no immunoassayable HTg. Finally, sera obtained from patients after total thyroid ablation for thyroid carcinoma did not contain demonstrable HTg. The sensitivity of the assay is 1.6 ng/ml, and HTg was detectable in 74% of 95 normal subjects. The mean concentration was 5.1 ng/ml +/-0.49 SEM (range <1.6-20.7 ng/ml). Day to day variation in HTg levels is large in some euthyroid subjects and nearly absent in others. HTg was detectable in 90% of the sera obtained in 23 pregnant women at delivery in whom a mean concentration of 10.1 ng/ml +/-1.3 SEM was observed. The mean level for the corresponding newborn infants at birth was 29.3 ng/ml +/-4.7 SEM a value significantly higher than the mean maternal HTg concentration (P <0.01). A group of 17 thyrotoxic individuals all had elevated HTg levels; the mean for this group was 344.8 ng/ml +/-90.7 SEM. In the acute phase of subacute thyroiditis HTg was also elevated in all of 12 patients, and the mean for this group was 136.8 ng/ml +/-74.6 SEM.
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Carani C, Isidori AM, Granata A, Carosa E, Maggi M, Lenzi A, Jannini EA. Multicenter study on the prevalence of sexual symptoms in male hypo- and hyperthyroid patients. J Clin Endocrinol Metab 2005; 90:6472-9. [PMID: 16204360 DOI: 10.1210/jc.2005-1135] [Citation(s) in RCA: 229] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Thyroid hormones have a dramatic effect on human behavior. However, their role on sexual behavior and performance has seldom been investigated in men. OBJECTIVE The objective of this study was to evaluate the prevalence of sexual dysfunctions in patients with hyper- and hypothyroidism and their resolution after normalization of thyroid hormone levels. DESIGN AND SETTING We conducted a multicenter prospective study at endocrinology and andrology clinics in university hospitals. PATIENTS The study included 48 adult men, 34 with hyperthyroidism and 14 with hypothyroidism. MAIN OUTCOME MEASURES Subjects were screened for hypoactive sexual desire (HSD), erectile dysfunction (ED), premature ejaculation (PE), and delayed ejaculation (DE) on presentation and 8-16 wk after recovery from the thyroid hormone disorder. RESULTS In hyperthyroid men, HSD, DE, PE, and ED prevalence was 17.6, 2.9, 50, and 14.7%, whereas in hypothyroid men, the prevalence of HSD, DE, and ED was 64.3% and of PE was 7.1%. After thyroid hormone normalization in hyperthyroid subjects, PE prevalence fell from 50 to 15%, whereas DE was improved in half of the treated hypothyroid men. Significant changes were found in the subdomains of the International Index of Erectile Function; ejaculation latency time doubled after treatment of hyperthyroidism (from 2.4 +/- 2.1 to 4.0 +/- 2.0 min), whereas for hypothyroid men it declined significantly, from 21.8 +/- 10.9 to 7.4 +/- 7.2 (P < 0.01 for both). TSH and thyroid hormone levels normalized rapidly after treatment, and changes in circulating sex steroids partially reflected the changes in SHBG levels. CONCLUSIONS In summary, most patients with thyroid hormone disorders experience some sexual dysfunctions, which can be reversed by normalizing thyroid hormone levels. Despite the associated changes in sex hormone levels, the high prevalence of ejaculatory disorders and their prompt reversibility suggest a direct involvement of thyroid hormones in the physiology of ejaculation.
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Multicenter Study |
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Negro R, Schwartz A, Gismondi R, Tinelli A, Mangieri T, Stagnaro-Green A. Universal screening versus case finding for detection and treatment of thyroid hormonal dysfunction during pregnancy. J Clin Endocrinol Metab 2010; 95:1699-707. [PMID: 20130074 DOI: 10.1210/jc.2009-2009] [Citation(s) in RCA: 227] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
CONTEXT Thyroid disease during pregnancy has been associated with multiple adverse outcomes. Whether all women should be screened for thyroid disease during pregnancy is controversial. OBJECTIVE The objective of the study was to determine whether treatment of thyroid disease during pregnancy decreases the incidence of adverse outcomes and compare the ability of universal screening vs. case finding in detecting thyroid dysfunction. DESIGN Women in the first trimester were randomly assigned to the universal screening group or case-finding group. Women in both groups were stratified as high risk or low risk based on risk factors for thyroid disease. All women in the universal screening group, and high-risk women in the case-finding group, were immediately tested for free T(4), TSH, and thyroid peroxidase antibody. Low-risk women in the case-finding group had their sera tested postpartum. SETTING The study was conducted at two ambulatory clinics of community hospitals in southern Italy. PATIENTS A total of 4562 women were randomly assigned to the universal screening or case-finding group. INTERVENTION Intervention included levothyroxine in women with a TSH above 2.5 mIU/liter in TPO antibody-positive women and antithyroid medication in women with a undetectable TSH and elevated free T(4). MAIN OUTCOME MEASURE Total number of adverse obstetrical and neonatal outcomes was measured. RESULTS No significant differences were seen in adverse outcomes between the case-finding and universal screening groups. Adverse outcomes were less likely to occur among low-risk women in the screening group than those in the case-finding group. CONCLUSIONS Universal screening compared with case finding did not result in a decrease in adverse outcomes. Treatment of hypothyroidism or hyperthyroidism identified by screening a low-risk group was associated with a lower rate of adverse outcomes.
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Casey BM, Dashe JS, Wells CE, McIntire DD, Leveno KJ, Cunningham FG. Subclinical Hyperthyroidism and Pregnancy Outcomes. Obstet Gynecol 2006; 107:337-41. [PMID: 16449121 DOI: 10.1097/01.aog.0000197991.64246.9a] [Citation(s) in RCA: 198] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Subclinical hyperthyroidism has long-term sequelae that include osteoporosis, cardiovascular morbidity, and progression to overt thyrotoxicosis or thyroid failure. The objective of this study was to evaluate pregnancy outcomes in women with suppressed thyroid-stimulating hormone (TSH) and normal free thyroxine (fT(4)) levels. METHODS All women who presented to Parkland Hospital for prenatal care between November 1, 2000, and April 14, 2003, underwent thyroid screening by chemiluminescent TSH assay. Women with TSH values at or below the 2.5th percentile for gestational age and whose serum fT(4) levels were 1.75 ng/dL or less were identified to have subclinical hyperthyroidism. Those women screened and delivered of a singleton infant weighing 500 g or more were analyzed. Pregnancy outcomes in women identified with subclinical hyperthyroidism were compared with those in women whose TSH values were between the 5th and 95th percentiles. RESULTS A total of 25,765 women underwent thyroid screening and were delivered of singleton infants. Of these, 433 (1.7%) were considered to have subclinical hyperthyroidism, which occurred more frequently in African-American and/or parous women. Pregnancies in women with subclinical hyperthyroidism were less likely to be complicated by hypertension (adjusted odds ratio 0.66, 95% confidence interval 0.44-0.98). All other pregnancy complications and perinatal morbidity or mortality were not increased in women with subclinical hyperthyroidism. CONCLUSION Subclinical hyperthyroidism is not associated with adverse pregnancy outcomes. Our results indicate that identification of subclinical hyperthyroidism and treatment during pregnancy is unwarranted. LEVEL OF EVIDENCE II-2.
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Kalmijn S, Mehta KM, Pols HA, Hofman A, Drexhage HA, Breteler MM. Subclinical hyperthyroidism and the risk of dementia. The Rotterdam study. Clin Endocrinol (Oxf) 2000; 53:733-7. [PMID: 11155096 DOI: 10.1046/j.1365-2265.2000.01146.x] [Citation(s) in RCA: 188] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
UNLABELLED AIMS AND SUBJECTS: We investigated the prospective relationship between thyroid status and the risk of dementia and Alzheimer's disease among a random sample of 1843 participants, aged 55 years and over, from the population-based prospective Rotterdam Study. METHODS Thyroid status was measured at baseline (1990-93), through assessment of serum antibodies to thyroid peroxidase (TPO-Abs, positive: >10 IU/ml), serum TSH levels, and when TSH was abnormal (<0.4 or >4.0 mU/l), serum thyroxin levels (T4). At baseline and at follow up, after on average 2 years, participants were screened for dementia. Diagnoses were based on international criteria. RESULTS Persons with reduced TSH levels at baseline had a more than threefold increased risk of dementia (RR = 3.5, 95%CI: 1.2-10.0) and of Alzheimer's disease (RR = 3.5, 95%CI: 1.1-11.5), after adjustment for age and sex. Among persons with reduced TSH levels, T4 levels appeared to be positively related to the risk of dementia (RR per SD increase = 2.9, 95%CI: 0.7-12.2), although none of those who became demented had a T4 level above the normal range (>140 nmol/l). The risk of dementia was especially increased in subjects with low TSH who were positive for TPO-Abs (RR = 23.7, 95%CI: 4.0-140). CONCLUSIONS This is the first prospective study to suggest that subclinical hyperthyroidism in the elderly increases the risk of dementia and Alzheimer's disease.
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Lundgren E, Rastad J, Thrufjell E, Akerström G, Ljunghall S. Population-based screening for primary hyperparathyroidism with serum calcium and parathyroid hormone values in menopausal women. Surgery 1997; 121:287-94. [PMID: 9092129 DOI: 10.1016/s0039-6060(97)90357-3] [Citation(s) in RCA: 179] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND Population-based screenings for primary hyperparathyroidism have failed to systematically use intact parathyroid hormone (PTH) values for diagnosis, to explore prevalence and diagnostic criteria of normocalcemic hyperparathyroidism, and to attempt surgical verification of the disorder. METHODS A total of 5202 women (ages, 55 to 75 years) attending a population-based mammography screening were investigated for primary hyperparathyroidism. In women lacking a family history of hypercalcemia, significant renal impairment, or low urinary calcium excretion hyperparathyroidism was diagnosed on the basis of predetermined criteria encompassing lower intact serum PTH levels in hypercalcemia (serum PTH 25 ng/L or greater; reference range, 12 to 55 ng/L) than in two intervals of normocalcemia (serum PTH 35 or greater, greater than 55 ng/L). RESULTS Prevalence of hyperparathyroidism was 2.1% (n = 109). At diagnosis total serum calcium and serum PTH levels were 2.32 to 3.19 mmol/L and 34 to 300 ng/L, respectively, and 66% of the women exhibited normocalcemia. Repeated examination showed persistent normocalcemia in 30 patients, and all but two of them had normal ionized plasma calcium levels. Significantly higher serum calcium, serum PTH, and urine calcium--but not serum creatinine--levels were found in patients with hyperparathyroidism compared with matched control subjects from the screened population. Within an ongoing stratified treatment program, 59 of 60 patients who underwent operation exhibited pathologic parathyroid tissue (mean weight, 591 mg). CONCLUSIONS Substantial prevalence of sporadic primary hyperparathyroidism is demonstrated in a risk group. Although criteria for hyperparathyroidism recognition included patients with truly mild biochemical derangement, operative findings suggested underdiagnosis of the disorder.
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Abstract
There is abundant evidence that the endothelium plays a crucial role in the maintenance of vascular tone and structure. One of the major endothelium-derived vasoactive mediators is nitric oxide (NO), an endogenous messenger molecule formed in healthy vascular endothelium from the amino acid precursor L-arginine. Endothelial dysfunction is caused by various cardiovascular risk factors, metabolic diseases, and systemic or local inflammation. One mechanism that explains the occurrence of endothelial dysfunction is the presence of elevated blood levels of asymmetric dimethylarginine (ADMA)--an L-arginine analogue that inhibits NO formation and thereby can impair vascular function. Supplementation with L-arginine has been shown to restore vascular function and to improve the clinical symptoms of various diseases associated with vascular dysfunction.
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RICH C, BIERMAN EL, SCHWARTZ IL. Plasma nonesterified fatty acids in hyperthyroid states. J Clin Invest 2000; 38:275-8. [PMID: 13631057 PMCID: PMC293153 DOI: 10.1172/jci103799] [Citation(s) in RCA: 173] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Journal Article |
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Porcu E, Medici M, Pistis G, Volpato CB, Wilson SG, Cappola AR, Bos SD, Deelen J, den Heijer M, Freathy RM, Lahti J, Liu C, Lopez LM, Nolte IM, O'Connell JR, Tanaka T, Trompet S, Arnold A, Bandinelli S, Beekman M, Böhringer S, Brown SJ, Buckley BM, Camaschella C, de Craen AJM, Davies G, de Visser MCH, Ford I, Forsen T, Frayling TM, Fugazzola L, Gögele M, Hattersley AT, Hermus AR, Hofman A, Houwing-Duistermaat JJ, Jensen RA, Kajantie E, Kloppenburg M, Lim EM, Masciullo C, Mariotti S, Minelli C, Mitchell BD, Nagaraja R, Netea-Maier RT, Palotie A, Persani L, Piras MG, Psaty BM, Räikkönen K, Richards JB, Rivadeneira F, Sala C, Sabra MM, Sattar N, Shields BM, Soranzo N, Starr JM, Stott DJ, Sweep FCGJ, Usala G, van der Klauw MM, van Heemst D, van Mullem A, H.Vermeulen S, Visser WE, Walsh JP, Westendorp RGJ, Widen E, Zhai G, Cucca F, Deary IJ, Eriksson JG, Ferrucci L, Fox CS, Jukema JW, Kiemeney LA, Pramstaller PP, Schlessinger D, Shuldiner AR, Slagboom EP, Uitterlinden AG, Vaidya B, Visser TJ, Wolffenbuttel BHR, Meulenbelt I, Rotter JI, Spector TD, Hicks AA, Toniolo D, Sanna S, Peeters RP, Naitza S. A meta-analysis of thyroid-related traits reveals novel loci and gender-specific differences in the regulation of thyroid function. PLoS Genet 2013; 9:e1003266. [PMID: 23408906 PMCID: PMC3567175 DOI: 10.1371/journal.pgen.1003266] [Citation(s) in RCA: 172] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Accepted: 11/12/2012] [Indexed: 12/15/2022] Open
Abstract
Thyroid hormone is essential for normal metabolism and development, and overt abnormalities in thyroid function lead to common endocrine disorders affecting approximately 10% of individuals over their life span. In addition, even mild alterations in thyroid function are associated with weight changes, atrial fibrillation, osteoporosis, and psychiatric disorders. To identify novel variants underlying thyroid function, we performed a large meta-analysis of genome-wide association studies for serum levels of the highly heritable thyroid function markers TSH and FT4, in up to 26,420 and 17,520 euthyroid subjects, respectively. Here we report 26 independent associations, including several novel loci for TSH (PDE10A, VEGFA, IGFBP5, NFIA, SOX9, PRDM11, FGF7, INSR, ABO, MIR1179, NRG1, MBIP, ITPK1, SASH1, GLIS3) and FT4 (LHX3, FOXE1, AADAT, NETO1/FBXO15, LPCAT2/CAPNS2). Notably, only limited overlap was detected between TSH and FT4 associated signals, in spite of the feedback regulation of their circulating levels by the hypothalamic-pituitary-thyroid axis. Five of the reported loci (PDE8B, PDE10A, MAF/LOC440389, NETO1/FBXO15, and LPCAT2/CAPNS2) show strong gender-specific differences, which offer clues for the known sexual dimorphism in thyroid function and related pathologies. Importantly, the TSH-associated loci contribute not only to variation within the normal range, but also to TSH values outside the reference range, suggesting that they may be involved in thyroid dysfunction. Overall, our findings explain, respectively, 5.64% and 2.30% of total TSH and FT4 trait variance, and they improve the current knowledge of the regulation of hypothalamic-pituitary-thyroid axis function and the consequences of genetic variation for hypo- or hyperthyroidism. Levels of thyroid hormones are tightly regulated by TSH produced in the pituitary, and even mild alterations in their concentrations are strong indicators of thyroid pathologies, which are very common worldwide. To identify common genetic variants associated with the highly heritable markers of thyroid function, TSH and FT4, we conducted a meta-analysis of genome-wide association studies in 26,420 and 17,520 individuals, respectively, of European ancestry with normal thyroid function. Our analysis identified 26 independent genetic variants regulating these traits, several of which are new, and confirmed previously detected polymorphisms affecting TSH (within the PDE8B gene and near CAPZB, MAF/LOC440389, and NR3C2) and FT4 (within DIO1) levels. Gender-specific differences in the genetic effects of several variants for TSH and FT4 levels were identified at several loci, which offer clues to understand the known sexual dimorphism in thyroid function and pathology. Of particular clinical interest, we show that TSH-associated loci contribute not only to normal variation, but also to TSH values outside reference range, suggesting that they may be involved in thyroid dysfunction. Overall, our findings add to the developing landscape of the regulation of thyroid homeostasis and the consequences of genetic variation for thyroid related diseases.
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Research Support, U.S. Gov't, Non-P.H.S. |
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Koulouri O, Moran C, Halsall D, Chatterjee K, Gurnell M. Pitfalls in the measurement and interpretation of thyroid function tests. Best Pract Res Clin Endocrinol Metab 2013; 27:745-62. [PMID: 24275187 PMCID: PMC3857600 DOI: 10.1016/j.beem.2013.10.003] [Citation(s) in RCA: 172] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Thyroid function tests (TFTs) are amongst the most commonly requested laboratory investigations in both primary and secondary care. Fortunately, most TFTs are straightforward to interpret and confirm the clinical impression of euthyroidism, hypothyroidism or hyperthyroidism. However, in an important subgroup of patients the results of TFTs can seem confusing, either by virtue of being discordant with the clinical picture or because they appear incongruent with each other [e.g. raised thyroid hormones (TH), but with non-suppressed thyrotropin (TSH); raised TSH, but with normal TH]. In such cases, it is important first to revisit the clinical context, and to consider potential confounding factors, including alterations in normal physiology (e.g. pregnancy), intercurrent (non-thyroidal) illness, and medication usage (e.g. thyroxine, amiodarone, heparin). Once these have been excluded, laboratory artefacts in commonly used TSH or TH immunoassays should be screened for, thus avoiding unnecessary further investigation and/or treatment in cases where there is assay interference. In the remainder, consideration should be given to screening for rare genetic and acquired disorders of the hypothalamic-pituitary-thyroid (HPT) axis [e.g. resistance to thyroid hormone (RTH), thyrotropinoma (TSHoma)]. Here, we discuss the main pitfalls in the measurement and interpretation of TFTs, and propose a structured algorithm for the investigation and management of patients with anomalous/discordant TFTs.
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Review |
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Auer J, Scheibner P, Mische T, Langsteger W, Eber O, Eber B. Subclinical hyperthyroidism as a risk factor for atrial fibrillation. Am Heart J 2001; 142:838-42. [PMID: 11685172 DOI: 10.1067/mhj.2001.119370] [Citation(s) in RCA: 172] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
OBJECTIVES Atrial fibrillation is a well-known manifestation of hyperthyroidism. We studied whether subclinical hyperthyroidism with low serum thyrotropin concentrations and free thyroid hormone concentrations within the normal range in clinically euthyroid persons is a risk factor for subsequent atrial fibrillation. METHODS We studied 23,638 persons. The subjects were classified according to their serum thyrotropin concentrations: group 1 comprised those with normal values of serum thyrotropin concentration (>0.4-5.0 mU/L) and free tri-iodothyronine and free thyroxine concentrations were within the normal range (22,300 subjects), group 2 comprised those with both low serum thyrotropin values (</=0.03 mU/L) and elevated free tri-iodothyronine and free thyroxine concentrations (725 subjects), and group 3 comprised those with low values of serum thyrotropin (<0.4 mU/L) and free triiodothyronine and free thyroxine concentrations were within the normal range (613 subjects). RESULTS Atrial fibrillation was present in 513 persons (2.3%) in group 1 with normal values for serum thyrotropin, 100 (13.8%) in group 2 with overt hyperthyroidism, and 78 (12.7%) in group 3 with subclinical hyperthyroidism. The prevalence of atrial fibrillation in patients with low serum thyrotropin concentrations (<0.4 mU/L) was 13.3% compared with 2.3% in patients with normal values for serum thyrotropin (P <.01). The relative risk of atrial fibrillation in subjects with low serum thyrotropin and normal free tri-iodothyronine and free thyroxine concentrations, compared with those with normal concentrations of serum thyrotropin, was 5.2 (95% CI 2.1-8.7, P <.01). CONCLUSION A low serum thyrotropin concentration is associated with a >5-fold higher likelihood for the presence of atrial fibrillation with no significant difference between subclinical and overt hyperthyroidism.
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Comparative Study |
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Nakamura H, Noh JY, Itoh K, Fukata S, Miyauchi A, Hamada N. Comparison of methimazole and propylthiouracil in patients with hyperthyroidism caused by Graves' disease. J Clin Endocrinol Metab 2007; 92:2157-62. [PMID: 17389704 DOI: 10.1210/jc.2006-2135] [Citation(s) in RCA: 171] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Although methimazole (MMI) and propylthiouracil (PTU) have long been used to treat hyperthyroidism caused by Graves' disease (GD), there is still no clear conclusion about the choice of drug or appropriate initial doses. OBJECTIVE The aim of the study was to compare the MMI 30 mg/d treatment with the PTU 300 mg/d and MMI 15 mg/d treatment in terms of efficacy and adverse reactions. DESIGN, SETTING, AND PARTICIPANTS Patients newly diagnosed with GD were randomly assigned to one of the three treatment regimens in a prospective study at four Japanese hospitals. MAIN OUTCOME MEASURES Percentages of patients with normal serum free T(4) (FT4) or free T(3) (FT3) and frequency of adverse effects were measured at 4, 8, and 12 wk. RESULTS MMI 30 mg/d normalized FT4 in more patients than PTU 300 mg/d and MMI 15 mg/d for the whole group (240 patients) at 12 wk (96.5 vs. 78.3%; P = 0.001; and 86.2%, P = 0.023, respectively). When patients were divided into two groups by initial FT4, in the group of the patients with severe hyperthyroidism (FT4, 7 ng/dl or more, 64 patients) MMI 30 mg/d normalized FT4 more effectively than PTU 300 mg/d at 8 and 12 wk and MMI 15 mg/d at 8 wk, respectively (P < 0.05). No remarkable difference between the treatments was observed in patients with initial FT4 less than 7 ng/dl. Adverse effects, especially mild hepatotoxicity, were higher with PTU and significantly lower with MMI 15 mg/d compared with MMI 30 mg/d. CONCLUSIONS MMI 15 mg/d is suitable for mild and moderate GD, whereas MMI 30 mg/d is advisable for severe cases. PTU is not recommended for initial use.
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Comparative Study |
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Yau WW, Singh BK, Lesmana R, Zhou J, Sinha RA, Wong KA, Wu Y, Bay BH, Sugii S, Sun L, Yen PM. Thyroid hormone (T 3) stimulates brown adipose tissue activation via mitochondrial biogenesis and MTOR-mediated mitophagy. Autophagy 2019; 15:131-150. [PMID: 30209975 PMCID: PMC6287687 DOI: 10.1080/15548627.2018.1511263] [Citation(s) in RCA: 164] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 07/26/2018] [Accepted: 08/08/2018] [Indexed: 12/14/2022] Open
Abstract
The thyroid hormone triiodothyronine (T3) activates thermogenesis by uncoupling electron transport from ATP synthesis in brown adipose tissue (BAT) mitochondria. Although T3 can induce thermogenesis by sympathetic innervation, little is known about its cell autonomous effects on BAT mitochondria. We thus examined effects of T3 on mitochondrial activity, autophagy, and metabolism in primary brown adipocytes and BAT and found that T3 increased fatty acid oxidation and mitochondrial respiration as well as autophagic flux, mitophagy, and mitochondrial biogenesis. Interestingly, there was no significant induction of intracellular reactive oxygen species (ROS) despite high mitochondrial respiration and UCP1 induction by T3. However, when cells were treated with Atg5 siRNA to block autophagy, induction of mitochondrial respiration by T3 decreased, and was accompanied by ROS accumulation, demonstrating a critical role for autophagic mitochondrial turnover. We next generated an Atg5 conditional knockout mouse model (Atg5 cKO) by injecting Ucp1 promoter-driven Cre-expressing adenovirus into Atg5Flox/Flox mice to examine effects of BAT-specific autophagy on thermogenesis in vivo. Hyperthyroid Atg5 cKO mice exhibited lower body temperature than hyperthyroid or euthyroid control mice. Metabolomic analysis showed that T3 increased short and long chain acylcarnitines in BAT, consistent with increased β-oxidation. T3 also decreased amino acid levels, and in conjunction with SIRT1 activation, decreased MTOR activity to stimulate autophagy. In summary, T3 has direct effects on mitochondrial autophagy, activity, and turnover in BAT that are essential for thermogenesis. Stimulation of BAT activity by thyroid hormone or its analogs may represent a potential therapeutic strategy for obesity and metabolic diseases. Abbreviations: ACACA: acetyl-Coenzyme A carboxylase alpha; AMPK: AMP-activated protein kinase; Acsl1: acyl-CoA synthetase long-chain family member 1; ATG5: autophagy related 5; ATG7: autophagy related 7; ATP: adenosine triphosphate; BAT: brown adipose tissue; cKO: conditional knockout; COX4I1: cytochrome c oxidase subunit 4I1; Cpt1b: carnitine palmitoyltransferase 1b, muscle; CQ: chloroquine; DAPI: 4',6-diamidino-2-phenylindole; DIO2: deiodinase, iodothyronine, type 2; DMEM: Dulbecco's modified Eagle's medium; EIF4EBP1: eukaryotic translation initiation factor 4E binding protein 1; Fabp4: fatty acid binding protein 4, adipocyte; FBS: fetal bovine serum; FCCP: carbonyl cyanide-4-(trifluoromethoxy)phenylhydrazone; FGF: fibroblast growth factor; FOXO1: forkhead box O1; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; GFP: green fluorescent protein; Gpx1: glutathione peroxidase 1; Lipe: lipase, hormone sensitive; MAP1LC3B: microtubule-associated protein 1 light chain 3; mRNA: messenger RNA; MTORC1: mechanistic target of rapamycin kinase complex 1; NAD: nicotinamide adenine dinucleotide; Nrf1: nuclear respiratory factor 1; OCR: oxygen consumption rate; PBS: phosphate-buffered saline; PCR: polymerase chain reaction; PPARGC1A: peroxisome proliferative activated receptor, gamma, coactivator 1 alpha; Pnpla2: patatin-like phospholipase domain containing 2; Prdm16: PR domain containing 16; PRKA: protein kinase, AMP-activated; RPS6KB: ribosomal protein S6 kinase; RFP: red fluorescent protein; ROS: reactive oxygen species; SD: standard deviation; SEM: standard error of the mean; siRNA: small interfering RNA; SIRT1: sirtuin 1; Sod1: superoxide dismutase 1, soluble; Sod2: superoxide dismutase 2, mitochondrial; SQSTM1: sequestosome 1; T3: 3,5,3'-triiodothyronine; TFEB: transcription factor EB; TOMM20: translocase of outer mitochondrial membrane 20; UCP1: uncoupling protein 1 (mitochondrial, proton carrier); ULK1: unc-51 like kinase 1; VDAC1: voltage-dependent anion channel 1; WAT: white adipose tissue.
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Hall R, Amos J, Ormston BJ. Radioimmunoassay of human serum thyrotrophin. BRITISH MEDICAL JOURNAL 1971; 1:582-5. [PMID: 5548300 PMCID: PMC1795217 DOI: 10.1136/bmj.1.5749.582] [Citation(s) in RCA: 163] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The double antibody radioimmunoassay of serum thyroid-stimulating hormone (TSH) allows measurement of circulating levels of the hormone in most normal subjects. The serum TSH level in normal subjects is 1.6 +/- 0.8muU/ml. Patients with non-toxic goitre and acromegaly have normal TSH levels. Values are always raised in hypothyroid patients (with primary thyroid disease) and are significantly lowered in those with hyperthyroidism. Of the many stimuli used in an attempt to raise TSH levels in normal adult subjects only three-synthetic thyrotrophin-releasing hormone, ethinyloestradiol, and carbimazole plus iodides-have been effective. The major clinical application of the TSH immunoassay lies in the diagnosis of minor degrees of hypothyroidism. An impaired response of serum TSH to synthetic thyrotrophin-releasing hormone should also help in the diagnosis of hypopituitarism affecting TSH production.
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