PMID- 32228286
OWN - NLM
STAT- MEDLINE
DCOM- 20210416
LR  - 20210416
IS  - 1532-2750 (Electronic)
IS  - 1098-612X (Linking)
VI  - 22
IP  - 12
DP  - 2020 Dec
TI  - Comparison of free thyroxine measurement by chemiluminescence and equilibrium 
      dialysis following (131)I therapy in hyperthyroid cats.
PG  - 1114-1120
LID - 10.1177/1098612X20906929 [doi]
AB  - OBJECTIVES: The first objective was to assess correlation between free thyroxine 
      (fT4) measurements by equilibrium dialysis (fT4ED; Antech Diagnostics) and a 
      chemiluminescent enzyme immunoassay (fT4CEIA; IMMULITE 2000 Veterinary Free T4 
      [Siemens Healthcare Diagnostics Products]) in hyperthyroid, otherwise healthy, 
      cats before (T0), and 1 month (T1) and 11-23 months (T2) after radioactive iodine 
      ((131)I) therapy. The second objective was to determine correlation between 
      thyroid status based on fT4 (by both techniques) and the gold standard, thyroid 
      scintigraphy. METHODS: Thyroid status, including thyroid-stimulating hormone 
      (TSH), total thyroxine (TT4) and fT4 serum concentrations, were assessed in 45 
      client-owned hyperthyroid cats before (T0), and 1 month (T1) and 11-23 months 
      (T2) after (131)I therapy. fT4 was determined by a chemiluminescent enzyme 
      immunoassay (CEIA) and equilibrium dialysis (ED). Quantitative thyroid 
      scintigraphy (with sodium 99m-Tc-pertechnetate) was performed at T2. RESULTS: 
      Spearman correlation between fT4CEIA and fT4ED was 0.81, 0.88 and 0.79 at T0, T1 
      and T2, respectively. fT4CEIA was consistently lower than fT4ED, with a median 
      difference of -5.4 pmol/l (P <0.001) and -4.9 pmol/l (P <0.0001) at T1 and T2, 
      respectively. At T2, all cats were identified as euthyroid based on thyroid 
      scintigraphy. None of the cats were identified as being hypothyroid, based on 
      serum TT4 and TSH measurements. Nine of 22 (40.9%) cats had an fT4CEIA below the 
      reference interval (RI) at T2, whereas only 2/22 (9.1%) cats had an fT4ED 
      concentration below the RI at T2. CONCLUSIONS AND RELEVANCE: Good correlation 
      exists between both assays at T1 and T2, but a significant systematic difference 
      is noted at both time points. This could be an indication for reconsideration of 
      the current RI, although further studies are warranted for assessing test 
      accuracy (in otherwise healthy cats and cats with non-thyroidal illness). At this 
      time, routine use of fT4CEIA after (131)I therapy is not advised in feline 
      patients.
FAU - Stammeleer, Lisa
AU  - Stammeleer L
AUID- ORCID: 0000-0002-9767-9384
AD  - Small Animal Department, Ghent University, Merelbeke, Belgium.
FAU - Buresova, Eva
AU  - Buresova E
AD  - Small Animal Department, Ghent University, Merelbeke, Belgium.
FAU - Stock, Emmelie
AU  - Stock E
AD  - Department of Medical Imaging of Domestic Animals, Ghent University, Merelbeke, 
      Belgium.
FAU - Feenstra, Laurien
AU  - Feenstra L
AD  - Department of Clinical Sciences of Companion Animals, Utrecht University, 
      Utrecht, The Netherlands.
FAU - Vandermeulen, Eva
AU  - Vandermeulen E
AD  - Department of Medical Imaging of Domestic Animals, Ghent University, Merelbeke, 
      Belgium.
FAU - Duchateau, Luc
AU  - Duchateau L
AD  - Biometrics Research Group, Ghent University, Merelbeke, Belgium.
FAU - Van de Maele, Isabel
AU  - Van de Maele I
AD  - Small Animal Department, Ghent University, Merelbeke, Belgium.
FAU - Daminet, Sylvie
AU  - Daminet S
AD  - Small Animal Department, Ghent University, Merelbeke, Belgium.
LA  - eng
PT  - Comparative Study
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20200331
PL  - England
TA  - J Feline Med Surg
JT  - Journal of feline medicine and surgery
JID - 100897329
RN  - 0 (Iodine Radioisotopes)
RN  - 0 (Iodine-131)
RN  - Q51BO43MG4 (Thyroxine)
SB  - IM
MH  - Animals
MH  - Cats/*blood
MH  - Dialysis/methods/*veterinary
MH  - Female
MH  - Hyperthyroidism/veterinary
MH  - Iodine Radioisotopes/*therapeutic use
MH  - Luminescent Measurements/methods/*veterinary
MH  - Male
MH  - Thyroxine/*blood
OTO - NOTNLM
OT  - CEIA
OT  - Hyperthyroidism
OT  - chemiluminescent enzyme immunoassay
OT  - equilibrium dialysis
OT  - fT4
OT  - free thyroxine
EDAT- 2020/04/02 06:00
MHDA- 2021/04/17 06:00
CRDT- 2020/04/02 06:00
PHST- 2020/04/02 06:00 [pubmed]
PHST- 2021/04/17 06:00 [medline]
PHST- 2020/04/02 06:00 [entrez]
AID - 10.1177/1098612X20906929 [doi]
PST - ppublish
SO  - J Feline Med Surg. 2020 Dec;22(12):1114-1120. doi: 10.1177/1098612X20906929. Epub 
      2020 Mar 31.