Gestation-specific reference intervals for fetal cardiac Doppler indices from 12 to 40 weeks of gestation

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 (2.5â97.5 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 4.40â13.93 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.

Download Full-text

Evaluation of Thyroid Function in Pregnant Women Using Automated Immunoassays

Clinical Chemistry ◽

10.1093/clinchem/hvab009 ◽

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.

Download Full-text

Effect of 1 mg/kg oral prednisolone on biochemical analytes in ten dogs: a cross-over study

Comparative Clinical Pathology ◽

10.1007/s00580-021-03246-9 ◽

2021 ◽

Author(s):

Helena Pettersson ◽

Carl Ekstrand ◽

Anna Hillström ◽

Inger Lilliehöök

Keyword(s):

Clinical Relevance ◽

Control Period ◽

Iron Concentration ◽

Oral Prednisolone ◽

Reference Intervals ◽

Specific Reference ◽

Test Results ◽

Prednisolone Treatment ◽

Anti Inflammatory ◽

And Control

AbstractPrednisolone is used for treatment of inflammatory, allergic, neoplastic, and immune-mediated diseases in dogs. As a glucocorticoid, prednisolone has biochemical effects, which may interfere with the interpretation of biochemistry test results. The aim of this study is to investigate the effects of prednisolone treatment in an anti-inflammatory dose on common biochemical analytes in dogs and to evaluate the clinical relevance of the changes. Ten beagle dogs, enrolled in a cross-over study, were treated with oral prednisolone (1 mg/kg 24 h) for 10 days. Blood samples were collected at day 0, 1, 3, 6, 9, 10, 12, 16, and 20. Data was analyzed using a general linear model with time and treatment as fixed factors. Pairwise comparisons were done between prednisolone and control period for each dog and sampling. Significant results were further evaluated for clinical relevance using laboratory-specific reference intervals and reference change values (RCVs), when available. Statistically significant changes were observed for ALP activity and iron concentration, which increased to levels exceeding the RCV, and several results were outside reference intervals. Phosphate and bile acids increased significantly, while amylase, lipase, and cholesterol decreased significantly, but with mean/median results remaining within reference intervals. Anti-inflammatory prednisolone treatment did not induce significant changes in ALT, GLDH, GGT, cPLI, glucose, or calcium. Treatment with an anti-inflammatory dose of prednisolone induced changes in several analytes. Only the increases in ALP and iron were of such magnitude that they are expected to affect the clinical interpretation of test results.

Download Full-text

Age- and Gender-Specific Reference Intervals for Fasting Blood Glucose and Lipid Levels in School Children Measured With Abbott Architect c8000 Chemistry Analyzer

Indian Journal of Clinical Biochemistry ◽

10.1007/s12291-012-0195-x ◽

2012 ◽

Vol 27 (2) ◽

pp. 141-146 ◽

Cited By ~ 4

Author(s):

Waleed Tamimi ◽

Esam Albanyan ◽

Yasmin Altwaijri ◽

Hani Tamim ◽

Fahad Alhussein

Keyword(s):

Blood Glucose ◽

School Children ◽

Fasting Blood Glucose ◽

Reference Intervals ◽

Specific Reference ◽

Lipid Levels ◽

Age And Gender ◽

And Gender ◽

Gender Specific ◽

Abbott Architect

Download Full-text

Inclusive and safe clinical trials Establishing race and time-specific reference intervals

10.26904/rf-136-1428679809 ◽

2021 ◽

Keyword(s):

Clinical Trials ◽

Reference Intervals ◽

Specific Reference ◽

Time Specific

Download Full-text

Serum TBA and GCA Levels Across Pregnancy and the Gestational Age-Specific Reference Intervals for Pregnant Chinese

Clinical Laboratory ◽

10.7754/clin.lab.2020.201043 ◽

2021 ◽

Vol 67 (06/2021) ◽

Author(s):

Rong Wang ◽

Hongmin Jiang ◽

Yongjun Wang ◽

Yuanqing Yang

Keyword(s):

Gestational Age ◽

Reference Intervals ◽

Specific Reference

Download Full-text

Comparing Ethnicity-Specific Reference Intervals for Clinical Laboratory Tests from EHR Data

The Journal of Applied Laboratory Medicine ◽

10.1373/jalm.2018.026492 ◽

2018 ◽

Vol 3 (3) ◽

pp. 366-377 ◽

Cited By ~ 3

Author(s):

Nadav Rappoport ◽

Hyojung Paik ◽

Boris Oskotsky ◽

Ruth Tor ◽

Elad Ziv ◽

...

Keyword(s):

Race And Ethnicity ◽

Laboratory Tests ◽

Clinical Laboratory ◽

Local Population ◽

Reference Intervals ◽

Medical Decision ◽

Specific Reference ◽

Healthy Individuals ◽

Electronic Health Record Data ◽

Novel Approach

Abstract Background The results of clinical laboratory tests are an essential component of medical decision-making. To guide interpretation, test results are returned with reference intervals defined by the range in which the central 95% of values occur in healthy individuals. Clinical laboratories often set their own reference intervals to accommodate variation in local population and instrumentation. For some tests, reference intervals change as a function of sex, age, and self-identified race and ethnicity. Methods In this work, we develop a novel approach, which leverages electronic health record data, to identify healthy individuals and tests for differences in laboratory test values between populations. Results We found that the distributions of >50% of laboratory tests with currently fixed reference intervals differ among self-identified racial and ethnic groups (SIREs) in healthy individuals. Conclusions Our results confirm the known SIRE-specific differences in creatinine and suggest that more research needs to be done to determine the clinical implications of using one-size-fits-all reference intervals for other tests with SIRE-specific distributions.

Download Full-text