Thyroid-stimulating Hormone Testing Research Articles

FT4 Should Replace TSH in Diagnosing Abnormal Thyroid Function

In this paper, I argue that the method for diagnosing abnormal thyroid function should be the free serum thyroxine (FT4) test. The current and most widely used method for diagnosis is the thyroid stimulating hormone (TSH) test. The FT4-first testing approach is more accurate and more cost-effective and should replace the TSH test.

Thyroid Status, Quality of Life, and Mental Health in Patients on Hemodialysis.

In the general population, there is increasing recognition of the effect of thyroid function on patient-centered outcomes, including health-related quality of life and depression. Although hypothyroidism is highly prevalent in hemodialysis patients, it is unknown whether thyroid status is a risk factor for impaired health-related quality of life or mental health in this population. We examined the association of thyroid status, defined by serum thyrotropin, with health-related quality of life and depressive symptoms over time in a prospective cohort of 450 patients on hemodialysis from 17 outpatient dialysis facilities from May of 2013 to May of 2015 who underwent protocolized thyrotropin testing, Short-Form 36 surveys, and Beck Depression Inventory-II questionnaires every 6 months. We examined the association of baseline and time-dependent thyrotropin categorized as tertiles and continuous variables with eight Short-Form 36 domains and Beck Depression Inventory-II scores using expanded case mix plus laboratory adjusted linear mixed effects models. In categorical analyses, the highest baseline thyrotropin tertile was associated with a five-point lower Short-Form 36 domain score for energy/fatigue (P=0.04); the highest time-dependent tertile was associated with a five-point lower physical function score (P=0.03; reference: lowest tertile). In continuous analyses, higher baseline serum thyrotropin levels (+Δ1 mIU/L) were associated with lower role limitations due to physical health (β=-1.3; P=0.04), energy/fatigue (β=-0.8; P=0.03), and pain scores (β=-1.4; P=0.002), equivalent to five-, three-, and five-point lower scores, respectively, for every 1-SD higher thyrotropin. Higher time-dependent thyrotropin levels were associated with lower role limitations due to physical health scores (β=-1.0; P=0.03), equivalent to a three-point decline for every 1-SD higher thyrotropin. Baseline and time-dependent thyrotropin were not associated with Beck Depression Inventory-II scores. In patients on hemodialysis, higher serum thyrotropin levels are associated with impaired health-related quality of life across energy/fatigue, physical function, and pain domains. Studies are needed to determine if thyroid-modulating therapy improves the health-related quality of life of hemodialysis patients with thyroid dysfunction.

Routine serum thyroid-stimulating hormone testing-optimizing pre-conception health or generating toxic knowledge?

Monitoring subclinical hypothyroidism (SCH) in women is believed to be important in terms of preventing overt hypothyroidism and optimizing the health and cognitive development of their children. Current systematic reviews have suggested an association between maternal SCH and adverse obstetric and neonatal outcomes. However, initiating the administration of thyroxine during pregnancy has failed to demonstrate appreciable health benefits. Hence there are calls by professional endocrine societies for optimizing serum thyroid-stimulating hormone (TSH) levels pre-conception. The strategy of ensuring that serum TSH levels are below 2.5 mIU/l during the pre-conception period has generated considerable uncertainty partly because the recommended level of <2.5 mIU/l is lower than those previously used to define the condition and partly due to uncertainty about the best screening programme clinicians can use in this context. Recalibrating the expected normal peri-conceptional range of serum TSH (<2.5 mIU/l), will have a significant impact on clinical services due to an inevitable increase in numbers of women diagnosed with SCH who will need to be investigated, treated and monitored. Serum TSH fulfils the criteria for a screening test and oral thyroxine is an inexpensive drug. Therefore, there is no reason to believe that screening cannot be undertaken in all women planning to conceive. Yet this approach will miss women whose pregnancies are unplanned and generate anxiety, further tests and many more prescriptions for thyroxine, coupled with the need for lifelong monitoring in affected women. A number of existing and ongoing randomized trials have evaluated the use of thyroxine in women with infertility or miscarriage with detectable thyroid auto-antibodies. These are unlikely to answer the question whether routine pre-conception testing for SCH in asymptomatic women is beneficial. Routine screening of women at risk of pregnancy and optimization of their thyroid status could result in significant health benefits for their offspring. Alternatively this approach could prove to be an expensive way of generating toxic knowledge resulting in anxiety, increased drug use and potential harm. Only large, appropriately designed studies can reveal the answer.

Temporal trends in thyroid-stimulating hormone (TSH) and thyroid peroxidase antibody (ATPO) testing across two phases of iodine fortification in Tasmania (1995-2013).

Tasmania is an island state of the Australian Commonwealth with a well-documented history of mild iodine deficiency. Between 2001 and 2009, Tasmania experienced two incremental phases of iodine fortification. To examine trends in thyroid-stimulating hormone (TSH) and thyroid peroxidase antibody (ATPO) testing and their relationship to different phases of iodine nutrition in the Tasmanian population between 1995 and 2013. Retrospective longitudinal study. The major primary care and largest public hospital pathology providers in Tasmania submitted data for all TSH and ATPO tests performed between 1995 and 2013. Data linkage methodology was used to determine trends in TSH and ATPO testing. A total of 1.66million TSH assessments, involving 389,910 individual patients, were performed in Tasmania between 1995 and 2013. There was approximately a fourfold increase in the overall rate of TSH testing during this period with the rate of incident TSH assessment remaining relatively stable over the study period. The incidence of overt suppression and elevation of TSH (TSH≤0.1mIU/L and ≥10mIU/L) declined 62.3% and 59.7%, respectively, with a trend for increased incidence of borderline TSH elevation ≥4.0mIU/L. The incidence of thyroid autoimmunity as determined by the proportion of abnormal ATPO results remained stable, with the absolute number of positive test results increasing during the study period. Iodine supplementation of this mildly iodine-deficient population was not associated with an obvious increase in incidence of overt thyroid dysfunction or autoimmunity. Whilst the volume of TSH testing increased over the study period, the increase was driven by patients undergoing follow-up TSH assessments.

Promoting resource stewardship: Reducing inappropriate free thyroid hormone testing.

Free thyroxine (fT4) and free triiodothyronine (fT3) tests are often ordered when not clinically warranted. Preventing laboratory overuse by reducing inappropriate fT4 and fT3 testing is one strategy to promote resource stewardship. (1) To characterize the frequency of inappropriate fT4 and fT3 testing and (2) to implement a quality improvement strategy aimed at reducing the number of these tests performed. Quality improvement tools were used to create sequential change ideas: (1) education of physicians regarding appropriate indications for ordering fT4/fT3 and (2) implementation of a hospital-wide laboratory and forced-function system with a reflex fT4. This study was conducted at an academic ambulatory care hospital in Toronto, Canada. The main outcomes were the differences in weekly median number of thyroid-stimulating hormone, fT4, and fT3 tests performed during the preintervention, education, and reflex periods using the Kruskal-Wallis test and analysis for special cause variation with statistical process control charts. The median number of fT4/fT3 processed per week was significantly reduced from 90/39 at baseline to 78/34 posteducation and 59/14 postreflex (P<.0001). Comparing preintervention to the reflex period, there was 34% reduction in fT4 and 64% reduction in fT3. The number of processed thyroid-stimulating hormone tests was stable with only 2% variation. Statistical process control charts demonstrated special cause variation following implementation of the reflex system for both fT4 and fT3. Inappropriate testing of free thyroid indices occurs frequently. The implementation of a reflex fT4 strategy after education was feasible in reducing overall testing by 49% and was effective in promoting resource stewardship.

Electronic Detection of Delayed Test Result Follow-Up in Patients with Hypothyroidism.

Delays in following up abnormal test results are a common problem in outpatient settings. Surveillance systems that use trigger tools to identify delayed follow-up can help reduce missed opportunities in care. To develop and test an electronic health record (EHR)-based trigger algorithm to identify instances of delayed follow-up of abnormal thyroid-stimulating hormone (TSH) results in patients being treated for hypothyroidism. We developed an algorithm using structured EHR data to identify patients with hypothyroidism who had delayed follow-up (>60days) after an abnormal TSH. We then retrospectively applied the algorithm to a large EHR data warehouse within the Department of Veterans Affairs (VA), on patient records from two large VA networks for the period from January 1, 2011, to December 31, 2011. Identified records were reviewed to confirm the presence of delays in follow-up. During the study period, 645,555 patients were seen in the outpatient setting within the two networks. Of 293,554 patients with at least one TSH test result, the trigger identified 1250 patients on treatment for hypothyroidism with elevated TSH. Of these patients, 271 were flagged as potentially having delayed follow-up of their test result. Chart reviews confirmed delays in 163 of the 271 flagged patients (PPV = 60.1%). An automated trigger algorithm applied to records in a large EHR data warehouse identified patients with hypothyroidism with potential delays in thyroid function test results follow-up. Future prospective application of the TSH trigger algorithm can be used by clinical teams as a surveillance and quality improvement technique to monitor and improve follow-up.

Laboratory Evaluation of Vocal Fold Paralysis and Paresis

This study aimed to assess the value of comprehensive laboratory evaluation in patients with vocal fold paralysis or paresis. This is a retrospective chart review. Records of 231 patients with vocal fold paralysis or paresis were reviewed to determine whether there is a significant increase in the number of abnormal test results compared with rates of abnormal results for these tests in the general population and whether testing resulted in clinically important diagnosis. Laboratory data were collected from charts from initial visits from 2010 to 2014 and compared with national data. When controlled for age and sex, white blood cell count was found to have a significantly higher rate of abnormal test results (P < 0.001) in patients with vocal fold paralysis or paresis than the general population. Although hemoglobin, thyroid-stimulating hormone, and thyroid antibody tests were more likely to be abnormal in our patient population, the trend was not statistically significant. Further, the prevalence of syphilis and myasthenia gravis was found to be higher in these subjects than their respective national prevalences, and the incidence of Lyme disease was found to be higher than the national prevalence of Lyme disease. Several patients were diagnosed with medically important conditions such as diabetes, thyroid dysfunction, syphilis, myasthenia gravis, and Lyme disease based on these tests. This study suggests that comprehensive testing of patients with vocal fold movement disorders results in diagnoses that would be missed without a comprehensive evaluation, some of which are important medically, although their causal relationship to vocal fold paralysis or paresis was not investigated or established.

Managing thyroid disease in general practice.

Serum thyroid-stimulating hormone (TSH) testing is the best screening tool for thyroid dysfunction. When TSH levels are in the reference range, additional tests such as free thyroxine, free triiodothyronine or thyroid antibodies rarely add value, except in patients with pituitary disease, when TSH is unreliable. Overt hypothyroidism and subclinical hypothyroidism with TSH levels >10 mU/L can be treated without further investigation. The health impact of subclinical hypothyroidism with mildly elevated levels of TSH (4-10 mU/L) remains uncertain, particularly in older people; treatment or observation are reasonable options. Thyroxine remains standard treatment for hypothyroidism, with optimal dosage determined by clinical response and serum TSH. Hyperthyroidism is commonly caused by Graves' disease, thyroiditis or toxic nodular goitre. The cause should be established before offering treatment. Radionuclide scanning is the imaging modality of choice. Positive TSH-receptor antibodies indicate Graves' disease. Thyroid ultrasound is indicated for assessment of palpable goitre and thyroid nodules. It is not part of routine assessment of hyperthyroidism or hypothyroidism. Overzealous use of ultrasound identifies clinically unimportant thyroid nodules and can lead to overdiagnosis of thyroid cancer. For thyroid nodules, the key investigation is ultrasound-guided fine needle aspiration biopsy, depending on size and sonographic appearance. Biopsy should not be performed routinely on small nodules <1 cm. It remains controversial whether pregnant women should be screened for thyroid disease. Reference intervals for thyroid function tests during pregnancy are not well established, and it is uncertain whether thyroxine treatment for pregnant women with serum TSH levels between 2.5 and 4.0 mU/L is beneficial. Iodine supplementation is recommended during pregnancy.

How well does the capillary thyroid-stimulating hormone test for newborn thyroid screening predict the venous free thyroxine level?

ObjectivesTo determine, in newborn infants referred with elevated capillary thyroid-stimulating hormone (TSH), a threshold below which a frankly subnormal venous free thyroxine (fT4) level of <10 pmol/L is unlikely, so...

American Association Of Clinical Endocrinologists And American College Of Endocrinology Position Statement On Thyroid Dysfunction Case Finding

Hypothyroidism and hyperthyroidism can be readily diagnosed and can be treated in a safe, cost-effective manner. Professional organizations have given guidance on how and when to employ thyroid-stimulating hormone testing for the detection of thyroid dysfunction. Most recently, the United States Preventive Services Task Force did not endorse screening for thyroid dysfunction based on a lack of proven benefit and potential harm of treating those with thyroid dysfunction, which is mostly subclinical disease. The American Association of Clinical Endocrinologists (AACE) is concerned that this may discourage physicians from testing for thyroid dysfunction when clinically appropriate. Given the lack of specificity of thyroid-associated symptoms, the appropriate diagnosis of thyroid disease requires biochemical confirmation. The Thyroid Scientific Committee of the AACE has produced this White Paper to highlight the important difference between screening and case-based testing in the practice of clinical medicine. We recommend that thyroid dysfunction should be frequently considered as a potential etiology for many of the nonspecific complaints that physicians face daily. The application and success of safe and effective interventions are dependent on an accurate diagnosis. We, therefore, advocate for an aggressive case-finding approach, based on identifying those persons most likely to have thyroid disease that will benefit from its treatment.

Should Free Thyroxine Go Back into the Routine Thyroid Profile?

Many clinical chemistry laboratories offer thyroid-stimulating hormone (TSH) alone as a first-line test of thyroid function, and only reflex a free thyroxine (fT4) test if the TSH result is abnormal (i. e., outside of the laboratory reference range). In secondary hypothyroidism, a low fT4 may be accompanied by a low or a normal TSH level. A testing strategy that measures baseline TSH only risks missing cases of secondary hypothyroidism in which the TSH level is normal. The current authors examined 26,106 consecutive thyroid function test (TFT) results in our initial analysis. If the TFT results were compatible with hypopituitarism, with fT4 below the reference range (9-20 pmol/L) and a TSH result ≤5 mU/L (reference range: 0.5-5 mU/L), the laboratory performed further tests of pituitary function. The cost of identifying pituitary insufficiency by measuring both fT4 and TSH was estimated for our population (in 2004 and 2013) and compared with 2 other relevant studies. A total of 121 patients had a normal TSH with a low fT4. 8 new cases of secondary hypopituitarism were identified when fT4 was combined with TSH as the front-line TFT profile. Of these, 5 were found to have pituitary adenomas, 2 of which were macroprolactinomas. The reagent cost of identifying each case by inclusion of fT4 in the TFT profile decreased from £11,568 (€16,089) in 1998 to £1451 (€2018) in 2013. 8 cases of pituitary insufficiency would not have been identified with a strategy of TSH testing alone, which calls for the addition of fT4 to the routine TFT profile. The cost per case of identifying those with pituitary insufficiency by additional measurement of fT4 has become cheaper with time.

Abstract 11545: Moving to a Highly Walkable Neighborhood and Incidence of Hypertension: A Propensity-score Matched Cohort Study

Introduction: Despite growing interest in the built environment and its impact on cardiovascular health, little is known about whether moving to a neighborhood more conducive to walking influences one’s risk of hypertension, a key risk factor of cardiovascular diseases. Objective: To conduct the first cohort study examining the association between moving to a highly walkable neighborhood and the risk of incident hypertension among a population-based sample of adults in Ontario, Canada. Methods: From the Canadian Community Health Survey (2001-2010), we identified a propensity-score matched cohort of 1057 pairs of Canadian adults who moved from a low (Walk Score&lt;90) walkability neighborhood to either a high (Walk Score≥90) or another low walkability neighborhood. The Walk Score (www.walkscore.com) is a walkability index shown to be valid in multiple geographic locations and at multiple spatial scales. The matched groups were well balanced on 16 important factors, including age, income, marital status and body-mass index. Incident hypertension was ascertained by linking the cohort to administrative health databases using a validated algorithm. Thyroid stimulating hormone testing and annual health examinations were used as the control events. Results: We observed a 42% lower risk of incident hypertension among those who moved from a low to high walkability neighborhood vs. those who moved from a low to another low walkability neighborhood (p=0.03) (Figure below). The incidence rate of hypertension was 8.6 per 1,000 person-years among the low to high walkability movers compared to 14.9 per 1,000 person-years among the low to low walkability movers. There were no significant differences in the control event rates between the two mover groups. Conclusions: Moving to a highly walkable neighborhood was associated with a significant protective effect on hypertension incidence, suggesting that the built environment can positively influence cardiovascular health.

Aggressive case finding: a clinical strategy for the documentation of thyroid dysfunction.

Ideas and Opinions18 August 2015Aggressive Case Finding: A Clinical Strategy for the Documentation of Thyroid DysfunctionJames V. Hennessey, MD, Irwin Klein, MD, Kenneth A. Woeber, MD, Rhoda Cobin, MD, and Jeffrey R. Garber, MDJames V. Hennessey, MDFrom Harvard Medical School, Beth Israel Deaconess Medical Center, and Harvard Vanguard Medical Associates, Boston, Massachusetts; New York University School of Medicine and Icahn School of Medicine at Mount Sinai, New York, New York; University of California, San Francisco Medical School, San Francisco, California; and American Association of Clinical Endocrinologists Thyroid Scientific Taskforce, Jacksonville, Florida.Search for more papers by this author, Irwin Klein, MDFrom Harvard Medical School, Beth Israel Deaconess Medical Center, and Harvard Vanguard Medical Associates, Boston, Massachusetts; New York University School of Medicine and Icahn School of Medicine at Mount Sinai, New York, New York; University of California, San Francisco Medical School, San Francisco, California; and American Association of Clinical Endocrinologists Thyroid Scientific Taskforce, Jacksonville, Florida.Search for more papers by this author, Kenneth A. Woeber, MDFrom Harvard Medical School, Beth Israel Deaconess Medical Center, and Harvard Vanguard Medical Associates, Boston, Massachusetts; New York University School of Medicine and Icahn School of Medicine at Mount Sinai, New York, New York; University of California, San Francisco Medical School, San Francisco, California; and American Association of Clinical Endocrinologists Thyroid Scientific Taskforce, Jacksonville, Florida.Search for more papers by this author, Rhoda Cobin, MDFrom Harvard Medical School, Beth Israel Deaconess Medical Center, and Harvard Vanguard Medical Associates, Boston, Massachusetts; New York University School of Medicine and Icahn School of Medicine at Mount Sinai, New York, New York; University of California, San Francisco Medical School, San Francisco, California; and American Association of Clinical Endocrinologists Thyroid Scientific Taskforce, Jacksonville, Florida.Search for more papers by this author, and Jeffrey R. Garber, MDFrom Harvard Medical School, Beth Israel Deaconess Medical Center, and Harvard Vanguard Medical Associates, Boston, Massachusetts; New York University School of Medicine and Icahn School of Medicine at Mount Sinai, New York, New York; University of California, San Francisco Medical School, San Francisco, California; and American Association of Clinical Endocrinologists Thyroid Scientific Taskforce, Jacksonville, Florida.Search for more papers by this authorAuthor, Article, and Disclosure Informationhttps://doi.org/10.7326/M15-0762 Annals Author Insight Video - James V. Hennessey, MD In this video, James V. Hennessey, MD, offers additional insight into his Ideas and Opinions piece, "Aggressive Case Finding: A Clinical Strategy for the Documentation of Thyroid Dysfunction." SectionsAboutFull TextPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinkedInRedditEmail Thyroid dysfunction is common, is readily diagnosed, and is treated in a cost-effective manner. Recently, the U.S. Preventive Services Task Force did not recommend screening for thyroid dysfunction in nonpregnant adults because of a lack of evidence that screening of asymptomatic patients affects clinical outcomes (1, 2). In contrast, over the last decade, 7 professional organizations, including the American Association of Clinical Endocrinologists, American Thyroid Association, and Latin American Thyroid Society, have given guidance on how and when to use thyroid-stimulating hormone (TSH) testing for the millions of Americans with undiagnosed thyroid dysfunction (Table) (3, 4).Table 1.Recommendations of 8 ...

Postoperative Treatment in a Patient After Hemithyroidectomy: the Therapeutic Challenges of a Hidden Thyrotropinoma

Objectives: We report the unusual case of a patient with a thyrotropinoma, discovered after a hemithyroidectomy for a suspicious thyroid nodule, and its therapeutic challenges. Materials and methods: In a patient who underwent hemithyroidectomy for cold thyroid nodule, hyperthyroid symptoms persisted, despite stopping levothyroxine treatment. Further investigation was carried out through the following laboratory tests: thyroid-stimulating hormone (TSH) test; free thyroxine (fT4) test; and the thyrotropin releasing hormone (TRH) test. A pituitary magnetic resonance imaging (MRI) scan and genetic analysis was also carried out. The test results confirmed the diagnosis of a thyrotropinoma. Results: Treatment with long-acting somatostatin analogues normalised thyroid hormones and symptoms of hyperthyroidism. Conclusion: The diagnostic approach to the thyroid nodule should include a detailed clinical and biochemical examination. Initial biochemical evaluation by TSH alone does not allow detecting inappropriate TSH secretion that may increase the risk of thyroid malignancy. In case of a thyrotropinoma, the ideal treatment consists of combined care of central and peripheral thyroid disease.

Thyroid function testing in primary care: overused and under-evidenced? A study examining which clinical features correspond to an abnormal thyroid function result.

Diagnostic testing is increasing in primary care, including for thyroid disease. This study examined which clinical features were associated with an abnormal thyroid stimulating hormone (TSH) result. This was a cross-sectional study in one general practice of 16,487 patients in Exeter, Devon, UK. We examined the primary care records relating to every TSH test taken in the year from August 2012, and extracted symptoms and/or the indication for testing. Associations with an abnormal result were tested using multivariable logistic regression. A cohort study was then performed of 100 patients newly recorded with each of the six features associated with an abnormal test result in the cross-sectional study, and the proportions tested for TSH and the results of that testing identified. Two thousand thirty-five patients (12% of the practice population) had TSH testing in the year. Of these 35 (1.7%) had a TSH >4.5 mIU/l, suggesting hypothyroidism, and 7 (0.3%) had TSH <0.01 mIu/l suggesting hyperthyroidism. Features associated with an abnormal TSH were: pregnancy, odds ratio 41 (95% confidence interval 9.3-180), constipation 9.7 (2.1-45), palpitations 23 (3.4-150), hair loss, 21 (2.0-230), weight gain, 18 (1.6-190) and diarrhoea, 13 (1.2-130); in separate analyses only pregnancy and constipation were associated with a raised TSH, and the remaining four features with a low TSH. The diagnostic yield of thyroid disease in this study was 2.1% suggests testing could be better targeted without missing diagnoses. The symptoms associated with thyroid disease differ from those generally reported. This may represent fewer patients presenting with advanced disease.

Tiroid Fonksiyon Testlerinin Gebelikteki Değişimi ve Trimester Spesifik Referans Aralıklarının Tanıya Katkısı

Objective: Non pregnant reference ranges are not appropriate in pregnancy because of the pregnancy associated changes in thyroid physiology. The aim of the study is to determine thyroid hormone status in trimesters of pregnancy and to show the clinical significance of using pregnancy associated values in thyroid stimulating hormone (TSH), free triiodothyronine (fT3) and free thyroxine (fT4) tests. Material and Methods: 319 pregnant women followed by the gynaecology and obstetrics clinic of our hospital were prospectively included. All tests were measured by Abbott Architect i400SR analyzer with chemiluminescent microparticle immunoassay (CMIA) method. The results were given as median and 2.5-97.5 percentiles. Results: The study population was composed of 319 women with a mean±SD age of 26.8±4.8 years; 96 pregnant were in the 1st trimester (9-13 weeks), 84 in the 2nd trimester (16-20 weeks) and 139 in the 3rd trimester (24-28 weeks). Median (2.5-97.5 percentile) values for TSH were found as 1.062 (0.035-2.955), 1.527 (0.334-2.70) and 1.740 (0.540-4.420) mIU/L for the 1st, 2nd and 3rd trimesters respectively. When using non-pregnant cut-off values, subclinic hypothyroid patients would be misdiagnosed; 2/96 (2.08%), 2/84 (2.38%) and 4/139 (2.87%) in the 1st, 2nd and 3rd trimesters respectively. Pregnant values found in this study were also different from the American Thyroid Association (ATA) recommended cut-off's. Use of ATA cut-off's, (4/96) 4.16% in the 1st; (2/84); 2.38% in the 2nd and (12/139) 8.6% in the 3rd trimester would be misdiagnosed. Conclusion: We can conclude that thyroid function test levels can change during pregnancy and laboratory specific reference ranges should be established to avoid misinterpretation for all trimesters.

The role of hypothyroidism in the etiology and progression of dilated cardiomyopathy in Doberman Pinschers.

BackgroundHypothyroidism and dilated cardiomyopathy (DCM) are both common diseases in Doberman Pinschers. A possible influence of hypothyroidism on the etiology and progression of DCM is controversial.ObjectivesEvaluation of the role of hypothyroidism in etiology and progression of DCM.AnimalsA total of 175 Doberman Pinschers.MethodsIn this longitudinal prospective study, echocardiography and 24‐hour ambulatory ECG recordings were performed in all dogs as screening tests for DCM. Total thyroxine (TT4) and thyroid ultrasonography served as initial screening tests for hypothyroidism and low TT4 values were followed up by a thyroid stimulating hormone (TSH) test or free total thyroxine (fT 4)/cTSH measurements. Additionally, a follow‐up study of dogs affected by both DCM and hypothyroidism under optimal treatment for hypothyroidism was conducted.ResultsA total of 107 dogs were healthy, 45 dogs had DCM, 11 hypothyroidism, and 12 dogs had both DCM and hypothyroidism. TT 4 values as well as the thyroid volumes were equivalent in the healthy dogs and in those with DCM. Neither ventricular premature complexes nor echocardiographic parameters differed between healthy and hypothyroid dogs. Dogs with DCM had a 2.26‐fold (CI0.95 = 1.1–4.8) higher risk of also being affected by hypothyroidism. Despite optimal thyroid treatment of dogs with hypothyroidism and DCM, there was a progression of the heart disease.Conclusions and Clinical ImportanceThis study did not confirm a role of hypothyroidism in the etiology or progression of DCM. Treatment of hypothyroidism did not improve the clinical outcome.

118 Assessment of Serum Thyroid Stimulating Hormone Testing and Urine Drugs of Abuse Screening in Emergency Department Psychiatric Patients

118 Assessment of Serum Thyroid Stimulating Hormone Testing and Urine Drugs of Abuse Screening in Emergency Department Psychiatric Patients

Incidental finding: elevated TSH level

The use of thyroid-stimulating hormone (TSH) testing in routine laboratory screening and testing of TSH before administration of contrast medium, resulted in an increased number of incidentally detected elevated TSH levels. In the case of slightly increased values in asymptomatic patients, repeated measurement of TSH is recommended for confirmation. Confirmed elevated TSH levels should lead to additional measurements of the peripheral thyroid hormones, determination of thyroid autoantibodies and performance of thyroid gland ultrasound examination. The most common reasons for acquired subclinical and overt hypothyroidism are autoimmune diseases of the thyroid gland and in many cases substitution therapy with levothyroxine is then necessary. In subclinical hypothyroidism it remains unclear at which TSH levels the initiation of substitution therapy makes sense. In the case of simultaneously elevated peripheral thyroid hormones rare diseases, such as secondary hyperthyroidism and thyroid hormone resistance should be considered.

Thyroid Hormone Transport into Cellular Tissue

New research is demonstrating that thyroid hormone transport across cellular membranes plays an important role in intracellular triiodothyronine (T3) levels of peripheral and pituitary tissues and is proving to have considerable clinical significance. Reduced T4 and T3 transport into the cells in peripheral tissues is seen with a wide range of common conditions, including insulin resistance, diabetes, depression, bipolar disorder, hyperlipidemia, chronic fatigue syndrome, fibromyalgia, neurodegenerative diseases, migraines, stress, anxiety, chronic dieting and aging, while the intracellular T3 level in the pituitary often remains unaffected. The pituitary has different transporters than every other tissue in the body. The thyroid transporters in the body are very energy dependent and are affected by numerous conditions, including low energy states, toxins and mitochondrial dysfunction, while the pituitary remains unaffected. Because the pituitary remains largely unaffected and is able to maintain intracellular T3 levels while the rest of the body suffers from significantly reduced intracellular T3 levels, there is no elevation in thyroid-stimulating hormone (TSH) despite the presence of wide-spread tissue hypothyroidism, making the TSH and other standard blood tests a poor marker to determine the presence or absence of hypothyroidism. Because the T4 transporter is more energy dependent than the transporter for T3, it is also not surprising that T4 preparations are generally ineffective in the presence of such conditions, while T3 replacement is shown to be beneficial. Thus, if a patient with a normal TSH presents with signs or symptoms consistent with hypothyroidism, which may include low basal body temperature, fatigue, weight gain, depression, cold extremities, muscle aches, headaches, decreased libido, weakness, cold intolerance, water retention, slow reflex relaxation phase or PMS, a combination of both clinical and laboratory assessment, which may include a T3/reverse T3 ratio and the level of sex hormone binding globulin (SHBG), should be used to determine the likely overall thyroid status and if a therapeutic trail of straight T3 or a T4/T3 combination is indicated and not based solely on standard thyroid function tests.