scholarly journals Rationalizing Thyroid Function Testing: Which TSH Cutoffs Are Optimal for Testing Free T4?

2017 ◽  
Vol 102 (11) ◽  
pp. 4235-4241 ◽  
Author(s):  
Meg Henze ◽  
Suzanne J Brown ◽  
Narelle C Hadlow ◽  
John P Walsh
Keyword(s):  
Thyroid Function ◽  
Reference Range ◽  
Health Study ◽  
Free T4 ◽  
Clinical Cohort ◽  
Thyroid Function Testing ◽  
Reflex Testing ◽  
Study Participants ◽  
Function Testing ◽  
Tsh Levels

Abstract Context Thyroid function testing often uses thyrotropin (TSH) measurement first, followed by reflex testing for free thyroxine (T4) if TSH is outside the reference range. The utility of different TSH cutoffs for reflex testing is unknown. Objective To examine different TSH cutoffs for reflex free T4 testing. Design, Setting, and Patients We analyzed concurrent TSH and free T4 results from 120,403 individuals from a single laboratory in Western Australia (clinical cohort) and 4568 Busselton Health Study participants (community cohort). Results In the clinical cohort, restricting free T4 measurement to individuals with TSH <0.3 or >5.0 mU/L resulted in a 22% reduction in free T4 testing compared with a TSH reference range of 0.4 to 4.0 mU/L; using TSH cutoffs of 0.2 and 6.0 mU/L resulted in a 34% reduction in free T4 testing. In the community cohort, the corresponding effect was less: 3.3% and 4.8% reduction in free T4 testing. In the clinical cohort, using TSH cutoffs of 0.2 and 6.0 mU/L, elevated free T4 would go undetected in 4.2% of individuals with TSH levels of 0.2 to 0.4 mU/L. In most, free T4 was marginally elevated and unlikely to indicate clinically relevant hyperthyroidism. Low free T4 would go undetected in 2.5% of individuals with TSH levels of 4 to 6 mU/L; in 94%, free T4 was marginally reduced and unlikely to indicate clinically relevant hypothyroidism. Conclusions Setting TSH cutoffs at 0.1 to 0.2 mU/L less than and 1 to 2 mU/L greater than the reference range for reflex testing of free T4 would reduce the need for free T4 testing, with minimal effect on case finding.

scholarly journals SUN-425 Indiscriminate Thyroid Function Testing on Acute Hospital Admissions Reveals a High Abnormality Rate Requiring Follow Up

2020 ◽  
Vol 4 (Supplement_1) ◽  
Author(s):  
Robert P McEvoy ◽  
Anthony O’Riordan ◽  
Mark J Hannon
Keyword(s):  
Thyroid Function ◽  
American Thyroid Association ◽  
Thyroid Function Tests ◽  
Free T4 ◽  
Patient Age ◽  
Function Tests ◽  
Patient Âgé ◽  
Thyroid Function Testing ◽  
Function Testing

Abstract The population attending the Medical Assessment Unit at our hospital comprises patients attending electively for investigation and acutely unwell patients presenting for unscheduled care. The standard panel of blood tests taken on arrival includes thyroid function tests (TFTs, i.e. TSH and free-T4), despite a recent review questioning the clinical utility of this practice [1]. We performed a retrospective audit to determine what proportion of our patients had abnormal thyroid function on presentation, and whether these abnormal test results were being followed up. Using the iSoft Clinical Manager software, a list was generated of all patients who attended the hospital between January 2018 and June 2018 inclusive. For each attendance, we recorded the date, medical record number, patient age, gender, and TFT result. Abnormal TFT results were classified as overt or subclinical hyper- or hypothyroid, or non-thyroid illness syndrome (NTIS), based on their admission TSH and free-T4. We then examined the hospital and primary care records of patients with abnormal TFTs to determine if they had ongoing thyroid follow up post discharge. In total, 2,298 patients attended over the 6-month study period. The mean patient age was 67.2 years, and 49% were female. Thyroid function tests were ordered on the day of attendance for 1,688 patients (73%). Of these, 181 results (11%) were abnormal: 20 overt hyperthyroid (11%), 72 subclinical hyperthyroid (40%), 12 overt hypothyroid (7%), 35 subclinical hypothyroid (19%), and 42 NTIS (23%). Twenty of these patients died within 3 months of the abnormal TFT result (4 overt hyperthyroid, 3 subclinical hyperthyroid, 3 overt hypothyroid, 6 subclinical hypothyroid, and 4 NTIS). Of the remaining 161 patients, 74 (46%) had not been followed up within 3 months (4 overt hyperthyroid, 34 subclinical hyperthyroid, 3 overt hypothyroid, 15 subclinical hypothyroid, and 18 NTIS). The low percentage of abnormal TFTs (11%) in this audit is in keeping with similar studies where thyroid function testing was performed on unselected hospital populations [1]. Subclinical hyperthyroidism was by far the most common abnormality found. A high percentage of abnormal tests (46%) were not followed up, with poor compliance with thyroid management guidelines [2]. Future work will investigate adoption of an ‘opt-in’ order system [3] and electronic alerts to flag abnormal results for follow-up. [1] Premawardhana LD. Thyroid testing in acutely ill patients may be an expensive distraction. Biochemia medica. 2017; 27(2): 300-307. [2] Ross DS et al. 2016 American Thyroid Association Guidelines for diagnosis and management of hyperthyroidism and other causes of thyrotoxicosis. Thyroid. 2016 Oct; 26(10):1343-1421. [3] Leis B et al. Altering standard admission order sets to promote clinical laboratory stewardship: a cohort quality improvement study. BMJ Qual Saf. 2019; 28(10): 846-52.

Biotin Measurement by Targeted LC-MS/MS: Method Development and Application to the Evaluation of Immunoassay Interference in Thyroid Function Tests

2019 ◽  
Vol 152 (Supplement_1) ◽  
pp. S4-S5
Author(s):  
Jeannie M Stubblefield ◽  
Jessica Becker ◽  
Jennifer Wallace ◽  
Uyen Vong ◽  
Dina Greene ◽  
...  
Keyword(s):  
Thyroid Function ◽  
Method Development ◽  
Thyroid Function Tests ◽  
Serum Samples ◽  
Free T4 ◽  
Function Tests ◽  
Normal Ranges ◽  
Thyroid Function Testing ◽  
Impact Patient Care ◽  
Function Testing

Abstract Introduction While biotin is widely used as a health and beauty supplement, patients rarely report the use of biotin supplements to clinicians. This can negatively impact patient care since biotin can falsely elevate or lower results in immunoassays that use biotinylated components. On the Beckman DxI platform, total T3 (T3), free T3 (FT3), and free T4 (FT4) assays are falsely elevated by excess biotin, while TSH and total T4 (T4) are unaffected. The goals of this study were to develop a method to measure serum biotin, to determine biotin concentrations in samples submitted for thyroid function testing, and to correlate biotin concentrations with immunoassay result patterns suggestive of biotin interference. Methods We developed and validated a targeted LC-MS/MS method to measure serum biotin (AMR: 5.4-500 mcg/L). Two collections of patient samples were tested using automated Beckman DxI assays for TSH (RR: 0.4-5.0 μIU/mL), T3 (RR: 73-178 ng/dL), FT3 (RR: 2.4-4.1 pg/mL), T4 (RR: 4.8-10.8 mcg/dL), and FT4 (RR: 0.6-1.2 ng/dL). The first collection included consecutive samples submitted for TSH and FT4 testing. To increase the probability of identifying samples with biotin interference, a middleware preselection algorithm was used to identify samples with a results pattern suggestive of biotin interference (normal to high TSH with elevated T3, FT3, and/or FT4). Results Two of the 94 samples consecutively submitted for thyroid function tests demonstrated biotin levels >AMR. TSH and FT4 were within normal ranges for one, while the other had normal TSH and elevated FT4 (biotin: 26 mcg/L). The preselection algorithm targeting normal to high TSH with elevated T3, FT3, and/or FT4 results flagged 83 samples, 21.7% of which had measurable biotin (5.71-194.3 mcg/L). Immunoassay results for TSH, T3, FT3, T4, and FT4 were obtained where there was sufficient volume for testing. Of these 38 samples, all samples with biotin >24 mcg/L had elevated results for 2(+) affected assays. Conclusions In this study, a targeted LC-MS/MS method to measure biotin in serum samples was developed and used to estimate the distribution of biotin concentrations in samples submitted for thyroid function testing. Comparison of immunoassay result patterns with biotin concentrations suggested an interference threshold around 24 mcg/L. The evaluation of consecutively submitted samples showed that biotin in excess of this interference threshold in patients receiving thyroid function tests on the Beckman DxI platform is rare. However, combining the preselection algorithm with quantitative biotin measurement by LC-MS/MS demonstrated that biotin interference does occur in these patient samples and should be evaluated when there are confounding results or result patterns suggestive of interference. In addition, the biotin LC-MS/MS method described here has additional clinical utility in the evaluation of suspected interference in any immunoassay that utilizes biotinylated components.

The Pharmacists' Role in Improving Guideline Compliance for Thyroid Function Testing in Patients With Heart Failure

2011 ◽  
Vol 25 (2) ◽  
pp. 195-200 ◽  
Author(s):  
Melanie E. Ziman ◽  
Hien T. Bui ◽  
Craig S. Smith ◽  
Lori A. Tsukiji ◽  
Veda M. Asmatey ◽  
...  
Keyword(s):  
Heart Failure ◽  
Drug Therapy ◽  
Thyroid Function ◽  
Thyroid Function Tests ◽  
Free T4 ◽  
Clinical Role ◽  
Function Tests ◽  
Thyroid Function Testing ◽  
Function Testing

This single-center retrospective pilot program’s objective was to utilize outpatient pharmacists to improve laboratory test adherence in chronic heart failure (CHF) patients overdue for thyroid function testing, thereby demonstrating the value of the outpatient pharmacist and justifying possible clinical role expansion. Thyroid disorders may contribute to CHF development, progression, and exacerbation. Testing is the standard of care in CHF patients per American Heart Association’s 2009 Guidelines. Delinquency was defined as labs not conducted within 1 year in patients with euthyroid history, within 6 months in patients with thyroid dysfunction, abnormal labs at any time without follow-up, or lab absence after thyroid medication initiation, adjustment, or discontinuation. Targeted 80 nonpregnant adult CHF patients with delinquent thyroid function tests were counseled to get thyroid labs at point of sale, via telephone, e-mail, or letter. In collaboration with physicians, pharmacists ordered thyroid-stimulating hormone (TSH) and free T4 (FT4) labs. For patients with abnormal laboratory results, pharmacists coordinated drug therapy and follow-up labs. Data were collected from November 1, 2009 to March 30, 2010. Seventy-two patients (90%) previously delinquent for thyroid function testing received relevant thyroid labs. Ten patients (12.5%) with abnormal thyroid function tests not on prior drug therapy received treatment.

scholarly journals Alternative Sequences of Thyrotropin and Free Thyroxine Assays for Routine Thyroid Function Testing

1998 ◽  
Vol 158 (3) ◽  
pp. 266 ◽  
Author(s):  
Robert A. Nordyke ◽  
Thomas S. Reppun ◽  
Lynn D. Madanay ◽  
Joseph C. Woods ◽  
Alan P. Goldstein ◽  
...  
Keyword(s):  
Thyroid Function ◽  
Free Thyroxine ◽  
Thyroid Function Testing ◽  
Function Testing

scholarly journals Case Report: De Quervain’s Thyroiditis as a Long-Term Sequelae Complication to SARS-CoV-2 Infection

2021 ◽  
pp. 64-70
Author(s):  
Mark Kong ◽  
Sarah La Porte
Keyword(s):  
Case Report ◽  
Thyroid Function ◽  
Elevated Serum ◽  
Subacute Thyroiditis ◽  
Thyroid Function Tests ◽  
Thyroid Function Testing ◽  
Neck Lump ◽  
Function Testing

A 44-year-old man presented with an enlarged painful lower anterior neck lump with elevated serum concentrations of free thyroxine (T4) and tri-iodothyronine (T3), alongside the presence of antithyroid peroxidase antibodies. Prior to presentation, the patient was demonstrating recovery from a SARS-CoV-2 infection that required sedation, intubation, and invasive ventilation in the intensive care unit (ICU) for 11 days. Ultrasound examination of the thyroid demonstrated features of De Quervain’s (subacute) thyroiditis. This corresponded to the clinical picture, and continuous thyroid function tests were arranged. Emerging evidence throughout the SARS-CoV-2 pandemic describes the long-term sequelae of the infection, including developing atypical effects on the thyroid gland. This case report emphasises the association of painful subacute thyroiditis with post-viral infection and its manifestation during recovery from severe SARS-CoV-2, suggesting that follow-up thyroid function testing should be considered in patients discharged from the ICU who develop neck discomfort.

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