Electrocardiogram Reference Range Indicator

SummaryAge-related trends in serum free thyroxine (FT4) and free triiodothyronine (FT3) concentrations were measured in 7248 euthyroid subjects (age-range 3 months to 106 years). 5700 were patients referred to hospitals for investigation of suspected thyroid dysfunction, but who were diagnosed euthyroid. 1548 were healthy blood donors (age-range 18-63 years) with no indication of thyroid dysfunction. FT4 concentrations were little affected by the age, the sex or the state of health of the subjects in either group. Serum FT3 concentrations were significantly affected by both age and health factors. The upper limit of the euthyroid reference range for young subjects up to 15 years was about 20% higher (10.4 pmol/1) than for adult subjects older than 25 years (8.8 pmol/1). The change in the upper limits typical of young subjects to that typical of adults occurred steadily over the decade 15–25 years. After this age, little further change occurred, especially in healthy subjects. Additionally, the lower limit of the euthyroid range for FT3 was extended by the inclusion in the reference group of patients referred to hospitals. Compared with the lower limit of the FT3 range for healthy subjects (5 pmol/1), the corresponding limit for referred subjects (young or adult) was 3.5–3.8 pmol/1. Broadening of the FT3 reference range was probably brought about by a significant number of patients in the hospital-referred group with the “1OW-T3 syndrome” of mild non-thyroidal illness. Accordingly, FT3 was inferior to FT4 in the discrimination of hypothyroidism, as FT4 was unaffected by this phenomenon. Effects of age and non-thyroidal illness on serum FT3 concentrations require great care when selecting subjects for a laboratory euthyroid reference range typical of the routine workload. Constraints on the choice of subjects for FT4 reference ranges are less stringent.

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Evaluation of normal reference range for thyroid uptake of technetium-99 m in a single centre UK population

Endocrine Abstracts ◽

10.1530/endoabs.50.p402 ◽

2017 ◽

Author(s):

Mavin Macauley ◽

Mohamed Shagwi ◽

Kim Howe ◽

Andrew Curry ◽

Elizabeth Howell ◽

...

Keyword(s):

Reference Range ◽

Single Centre ◽

Normal Reference Range ◽

Normal Reference ◽

Thyroid Uptake

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Low free T3 levels within the reference range independently predict cardiovascular mortality in the general population

Endocrine Abstracts ◽

10.1530/endoabs.56.oc1.5 ◽

2018 ◽

Author(s):

Joao Sergio Neves ◽

Catarina Viegas Dias ◽

Lia Leitao ◽

Miguel Bigotte Vieira ◽

Rita Magrico ◽

...

Keyword(s):

General Population ◽

Cardiovascular Mortality ◽

Reference Range ◽

Free T3

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Could Thyroid Disorders Be Better Understood and Dealt as a Thyroid Syndrome

International Journal of Innovative Research in Medical Science ◽

10.23958/ijirms/vol05-i08/900 ◽

2020 ◽

Vol 5 (08) ◽

pp. 326-328

Author(s):

Dr. Sushma Patil ◽

Dr. Vikrant Patil

Keyword(s):

Reference Range ◽

Well Being ◽

Thyroid Disorders ◽

Thyroid Function Tests ◽

Thyroid Disorder ◽

Serum Concentrations ◽

Comorbid Conditions ◽

Free T4 ◽

Research Perspective ◽

Wide Range

Thyroid disorders are common worldwide. Thyroid dysfunction, both hypo- and hyperthyroidism may increase the risk of cardiovascular disorders. Current thyroid function tests may have limitations since they only measure the total or free T4 and/or T3 and TSH serum concentrations in peripheral blood and not the effect of T4 or T3 serum on different specific target tissues. Several comorbid conditions can interfere with the absorption or increase the clearance of levothyroxine. Among patients treated with thyroid replacement, under or overmedicated may-be at risk for adverse health consequences. A wide range of drugs may interfere with levothyroxine absorption, metabolism, and action. Patients report a lack of well-being, despite reaching euthyroid reference range of TSH, with psychological distress. If we will consider Thyroid related conditions as a syndrome then research perspective at the pathophysiology, interrelation between symptoms and comorbidities will be much broader that can lead researchers to get insights of different pathways in which thyroid gland functioning can be perceived and dealt therapeutically. The deliberation of thyroid disorder as a syndrome can affluence our knowledge of correlating cofounders, action of thyroid hormones on target tissues, underlying cause and thyroid health.

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