Document Detail

The interaction of free fatty acids in radioimmunoassays for reverse triiodothyronine.
MedLine Citation:
PMID:  7096540     Owner:  NLM     Status:  MEDLINE    
We have investigated the effect of FFA on the RIA of rT3 because of our previous findings of a correlation between serum rT3 values and increased FFA concentrations during prolonged exercise and reports of interference by FFA in other thyroid hormone assays. Apparent rT3 values increased by 19% and 34% in in vivo studies of acute lipolysis in subjects 5 min post exercise or 10 min post heparin, respectively, while T3 and T4 concentrations were unchanged. Varying concentrations of palmitic acid were added in vitro to four normal sera, and the increase in FFA concentration correlated significantly with the increase in apparent rT3 values. The mean +/- SE of the regression slope was 9.3 +/- 1.8 ng/dl rT3/mM FFA (r = 0.96 +/- 0.02). The addition of linoleic acid produced a similar effect. T3 and T4 concentrations were unchanged. The interaction of FFA in the rT3 RIA was unrelated to the procedure used to separate the assay, to the concentration of 8-anilino-1-napthalene-sulfonic acid in the assay buffer, to FFA binding directly to the antisera or to use of a particular antisera. The magnitude of the effect was similar in charcoal-treated sera, and the addition of 2 mM palmitic acid to the assay standard curve decreased the y intercept but did not alter the slope, suggesting an interaction of rT3 with FFA, rather than change in affinity of the antisera.
M O'Connell; D C Robbins; C Bogardus; A G Burger; E Danforth
Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The Journal of clinical endocrinology and metabolism     Volume:  55     ISSN:  0021-972X     ISO Abbreviation:  J. Clin. Endocrinol. Metab.     Publication Date:  1982 Sep 
Date Detail:
Created Date:  1982-09-17     Completed Date:  1982-09-17     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0375362     Medline TA:  J Clin Endocrinol Metab     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  577-82     Citation Subset:  AIM; IM    
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MeSH Terms
Energy Intake
False Positive Reactions
Fatty Acids, Nonesterified / blood*
Heparin / diagnostic use
Linoleic Acid
Linoleic Acids / blood
Palmitic Acid
Palmitic Acids / blood
Physical Exertion
Radioimmunoassay* / methods
Triiodothyronine / blood*
Triiodothyronine, Reverse / blood*
Grant Support
Reg. No./Substance:
0/Fatty Acids, Nonesterified; 0/Linoleic Acids; 0/Palmitic Acids; 2197-37-7/Linoleic Acid; 57-10-3/Palmitic Acid; 5817-39-0/Triiodothyronine, Reverse; 6893-02-3/Triiodothyronine; 9005-49-6/Heparin

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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