Isarithmic Maps and the Continuity of Reference Interval Functions

1970 ◽  
Vol 52 (2) ◽  
pp. 92 ◽  
Author(s):  
Stig Nordbeck ◽  
Bengt Rystedt
Keyword(s):  
Reference Interval ◽  
Interval Functions ◽  
Continuity Of Reference

EXPRESS: Method dependent variation in TSH and FT4 reference intervals in pregnancy: a systematic review

2021 ◽  
pp. 000456322110269
Author(s):  
O E Okosieme ◽  
Medha Agrawal ◽  
Danyal Usman ◽  
Carol Evans
Keyword(s):  
Systematic Review ◽  
Reference Interval ◽  
First Trimester ◽  
Reference Intervals ◽  
Assay Method ◽  
Specific Reference ◽  
Upper Limits ◽  
Wide Range ◽  
Assay Methods ◽  
In Pregnancy

Background: Gestational TSH and FT4 reference intervals may differ according to assay method but the extent of variation is unclear and has not been systematically evaluated. We conducted a systematic review of published studies on TSH and FT4 reference intervals in pregnancy. Our aim was to quantify method-related differences in gestation reference intervals, across four commonly used assay methods, Abbott, Beckman, Roche, and Siemens. Methods: We searched the literature for relevant studies, published between January 2000 and December 2020, in healthy pregnant women without thyroid antibodies or disease. For each study, we extracted trimester-specific reference intervals (2.5–97.5 percentiles) for TSH and FT4 as well as the manufacturer provided reference interval for the corresponding non-pregnant population. Results: TSH reference intervals showed a wide range of study-to-study differences with upper limits ranging from 2.33 to 8.30 mU/L. FT4 lower limits ranged from 4.40–13.93 pmol/L, with consistently lower reference intervals observed with the Beckman method. Differences between non-pregnant and first trimester reference intervals were highly variable, and for most studies the TSH upper limit in the first trimester could not be predicted or extrapolated from non-pregnant values. Conclusions: Our study confirms significant intra and inter-method disparities in gestational thyroid hormone reference intervals. The relationship between pregnant and non-pregnant values is inconsistent and does not support the existing practice in some laboratories of extrapolating gestation references from non-pregnant values. Laboratories should invest in deriving method-specific gestation reference intervals for their population.

Evaluation of Thyroid Function in Pregnant Women Using Automated Immunoassays

2021 ◽  
Author(s):  
K Aaron Geno ◽  
Matthew S Reed ◽  
Mark A Cervinski ◽  
Robert D Nerenz
Keyword(s):  
Pregnant Women ◽  
Equilibrium Dialysis ◽  
Reference Interval ◽  
First Trimester ◽  
Reference Intervals ◽  
Free Thyroxine ◽  
Specific Reference ◽  
Childbearing Age ◽  
Thyroid Autoantibody ◽  
The Impact

Abstract Introduction Automated free thyroxine (FT4) immunoassays are widely available, but professional guidelines discourage their use in pregnant women due to theoretical under-recoveries attributed to increased thyroid hormone binding capacity and instead advocate the use of total T4 (TT4) or free thyroxine index (FTI). The impact of this recommendation on the classification of thyroid status in apparently euthyroid pregnant patients was evaluated. Methods After excluding specimens with thyroid autoantibody concentrations above reference limits, thyroid-stimulating hormone (TSH), FT4, TT4, and T-uptake were measured on the Roche Cobas® platform in remnant clinical specimens from at least 147 nonpregnant women of childbearing age and pregnant women at each trimester. Split-sample comparisons of FT4 as measured by the Cobas and equilibrium dialysis were performed. Results FT4 decreased with advancing gestational age by both immunoassay and equilibrium dialysis. TSH declined during the first trimester, remained constant in the second, and increased throughout the third, peaking just before delivery. Interpretation of TT4 concentrations using 1.5-times the nonpregnant reference interval classified 13.6% of first trimester specimens below the lower reference limit despite TSH concentrations within trimester-specific reference intervals. Five FTI results from 480 pregnant individuals (about 1.0%) fell outside the manufacturer’s reference interval. Conclusions Indirect FT4 immunoassay results interpreted in the context of trimester-specific reference intervals provide a practical and viable alternative to TT4 or FTI. Declining FT4 and increasing TSH concentrations near term suggest that declining FT4 is not an analytical artifact but represents a true physiological change in preparation for labor and delivery.

scholarly journals Sample Timing, Diagnosis of Subclinical Thyroid Dysfunction and Mortality in Acute Myocardial Infarction: ThyrAMI1 Study

2019 ◽  
Vol 105 (4) ◽  
pp. e1299-e1306 ◽  
Author(s):  
Salman Razvi ◽  
Owain Leng ◽  
Avais Jabbar ◽  
Arjola Bano ◽  
Lorna Ingoe ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Acute Myocardial Infarction ◽  
Thyroid Function ◽  
Thyroid Dysfunction ◽  
Reference Interval ◽  
Reference Ranges ◽  
Diagnosis And Prognosis ◽  
Time Period ◽  
All Cause Mortality ◽  
The Impact

Abstract Objective The objective of this study was to determine the impact of blood sample timing on the diagnosis of subclinical thyroid dysfunction (SCTD) and mortality in patients with acute myocardial infarction (AMI). Patients, Design, and Main Outcome Measures Patients with AMI had thyroid function evaluated on admission between December 2014 and December 2016 and those with abnormal serum thyrotropin (TSH) had repeat thyroid function assessed at least a week later. The association between sample timing and SCTD was evaluated by logistic regression analysis. Secondary outcomes were confirmation of SCTD on repeat testing and all-cause mortality up to June 2018. Results Of the 1806 patients [29.2% women, mean (± standard deviation) age of 64.2 (±12.1) years] analyzed, the prevalence of subclinical hypothyroidism (SCH) was 17.2% (n = 311) and subclinical hyperthyroidism (SHyper) was 1.2% (n = 22) using a uniform TSH reference interval. The risk of being diagnosed with SCTD varied by sample timing in fully-adjusted models. The risk of SCH was highest between 00.01 and 06.00 hours and lowest between 12.01 and 18.00 hours, P for trend <.001, and risk of SHyper was highest between 12.01 hours and 18.00 hours and lowest between 00.01 hours and 06.00 hours. Furthermore, time of the initial sample was associated with the risk of remaining in a SCH state subsequently. Mortality in SCH patients was not elevated when a uniform TSH reference interval was utilized. However, when time period–specific TSH reference ranges were utilized, the mortality risk was significantly higher in SCH patients with HR (95% CI) of 2.26 (1.01–5.19), P = .04. Conclusions Sample timing impacts on the diagnosis and prognosis of SCH in AMI patients. If sample timing is not accounted for, SCH is systemically misclassified, and its measurable influence on mortality is lost.

Assessment of copper accumulation in archived liver specimens from cats

2020 ◽  
pp. 1098612X2096135
Author(s):  
Punyamanee Yamkate ◽  
Randi M Gold ◽  
Panagiotis G Xenoulis ◽  
Katja Steiger ◽  
David C Twedt ◽  
...  
Keyword(s):  
Infectious Disease ◽  
Hepatic Steatosis ◽  
Dry Weight ◽  
Reference Interval ◽  
Copper Accumulation ◽  
Zonal Distribution ◽  
Tissue Samples ◽  
Hepatic Copper ◽  
Liver Copper ◽  
Flame Atomic Absorption

Objectives The aim of this study was to assess hepatic copper concentrations and zonal distribution in cat liver specimens. Methods For this study, 121 archived, formalin-fixed, paraffin-embedded liver specimens from cats were used. Tissue sections were stained for copper with rhodanine and scored from 0 (no copper accumulation) to 5 (panlobular copper accumulation). The tissue specimens were then deparaffinized and hepatic copper concentrations were measured using flame atomic absorption spectroscopy. Results Tissue samples were categorized into four groups based on histopathologic findings: (1) no significant histopathologic hepatic changes (n = 66); (2) hepatic steatosis (n = 18); (3) inflammatory or infectious disease (n = 24); and (4) neoplasia (n = 13). Of the 121 specimens, 13 (11%) stained positive for copper, with three having a score ⩾3. Thirty-seven specimens (31%) had copper concentrations above the reference interval ([RI] <180 µg/g dry weight liver). Copper concentrations in cats with hepatic inflammatory or infectious disease were significantly higher than cats with hepatic steatosis ( P = 0.03). Copper-staining score and concentration were positively correlated ( rs = 0.46, P <0.001). Conclusions and relevance Despite the fact that 31% of specimens had copper concentrations above the RI, only 11% showed positive copper staining and only 2.5% had a score ⩾3. Our findings suggest that hepatic copper concentrations greater than the upper limit of the RI are relatively common in cats. Further studies to determine the factors that influence hepatic copper staining in cats and to establish contemporary RIs for hepatic copper in healthy cats are warranted.

EXPRESS: Serum Carbohydrate Antigen72-4 levels decrease with age in females but not males in Beijing, China

2021 ◽  
pp. 000456322110269
Author(s):  
Tongmei Duan ◽  
Xun Chen ◽  
Jing Wu ◽  
Ronghai Li ◽  
Huijuan Guo ◽  
...  
Keyword(s):  
Age Groups ◽  
Reference Interval ◽  
Carbohydrate Antigen ◽  
Female Group ◽  
Healthy Population ◽  
Age Difference ◽  
Significant Difference ◽  
The Difference ◽  
And Gender ◽  
Beijing China

Objective: Carbohydrate antigen 72-4 (CA72-4) is widely used in the diagnosis and monitoring of many cancers. However, there are few studies on the differences of CA72-4 levels in terms of age and gender. Methods: 10957 healthy subjects were divided into two groups according to gender and three age groups. The serum CA72-4 were detected. Statistical analysis was performed by SPSS. Results: The CA72-4 level in female group was significantly higher than that in male group. The level of CA72-4 gradually decreased with age. Compared with the age >60 group, the CA72-4 levels were increased in the age 46-60 group and 16-45 group (P >0.05, respectively). To better observe the age difference, the age 16-45 and 46–60 group were combined into the age 16-60 group. In comparison to the age >60 group, the CA72-4 level of age 16-60 group was significantly increased (P =0.000). In the age >60 group, there was no difference between genders. Nevertheless, the difference between the sexes in the age 16-60 group was significant (P =0.023). Conclusions: The reference interval of CA72-4 for local healthy population was established. CA72-4 levels gradually decreased with the increase of age, and CA72-4 level in females aged 16-60 years (0-18.0 U/mL) was higher than in males (0-14.5 U/mL), however there was no gender difference in the age group above 60 years old (0-14.5 U/mL). Moreover, male CA72-4 was no significant difference among all age groups, while the potential mechanism of female changes with age needed further study.

Sign in / Sign up

Export Citation Format

Share Document