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Pinna
3,3'-Diiodothyronine concentrations in the sera of patients with nonthyroidal illnesses and brain tumors and of healthy subjects during acute stress.Pinna G, Hiedra L, Meinhold H, Eravci M, Prengel H, Brodel O, Graf KJ, Stoltenburg-Didinger G, Bauer M, Baumgartner A. J Clin Endocrinol Metab. 1998 Sep;83(9):3071-7.
"In this article we
describe the development of a highly sensitive, accurate, and
reproducible RIA for the measurement of 3,3'-diiodothyronine
(3,3'-T2) in human serum and brain tissue. The detection limits
were 1.8 fmol/g and 1.5 pmol/L in human brain tissue and serum,
respectively. Serum concentrations of 3,3'-T2 were measured in 4
groups of patients with nonthyroidal illnesses (NTI), i.e. brain
injuries (n = 15), sepsis (n = 24), liver disease (n = 22), and
brain tumors (n = 23). The mean serum concentration of 3,3'-T2 in
62 healthy controls was 46.6 +/- 20.0 pmol/L. 3,3'-T2 levels
declined significantly with increasing age. They were
significantly lower in patients with brain injury (34.2 +/- 19.4
pmol/L; P = 0.006), were at the upper limit of normal in patients
with sepsis (57.0 +/- 36.9 pmol/L; P = 0.06), and were elevated
in patients with liver disease (72.6 +/- 56.7 pmol/L; P = 0.04)
and brain tumors (89.0 +/- 40.9 pmol/L; P = 0.01). The serum
levels of T3 were significantly lower than those in controls in
all 4 patient groups. Serum concentrations of 3,3'-T2 were
significantly enhanced in 9 patients with hyperthyroidism (85.4
+/- 43.0 pmol/L; P = 0.01) and were reduced in 12 patients with
hypothyroidism (14.9 +/- 9.2 pmol/L; P = 0.001). In both normal
brain tissue, obtained either intraoperatively or excised
postmortem, and brain tumors, the concentrations of 3,3'-T2
ranged between 50-300 fmol/g. In healthy controls, 2 different
forms of acute stress (sleep deprivation and delivering a
lecture) significantly increased serum levels of T4 and T3, but
did not affect those of 3,3'-T2 or 3,5-T2. In conclusion, our
results show that, contrary to expectation, a low T3 syndrome in
NTI is not always associated with low serum concentrations of
3,3'-T2. The production of 3,3'-T2 in NTI seems to be regulated
in a disease-specific manner, resulting in unchanged, reduced, or
elevated hormone concentrations."
Elevated 3,5-diiodothyronine concentrations in the sera of patients with nonthyroidal illnesses and brain tumors.Pinna G, Meinhold H, Hiedra L, Thoma R, Hoell T, Graf KJ, Stoltenburg-Didinger G, Eravci M, Prengel H, Brodel O, Finke R, Baumgartner A. J Clin Endocrinol Metab. 1997
May;82(5):1535-42. "This study reports the development of a highly sensitive and reproducible RIA for the measurement of 3,5-diiodothyronine (3,5-T2) in human serum and tissue. The RIA employs 3-bromo-5-[125I]iodo-L-thyronine (3-Br-5-[125I]T1) as tracer, which was synthesized carrier free by an interhalogen exchange from 3,5-dibromo-L-thyronine (3,5-Br2T0). The detection limits were 1.0 fmol/g and 0.8 pmol/L in human brain tissue and serum, respectively. T3, diiodothyroacetic acid, and 3-monoiodothyronine cross-reacted with a 3,5-T2 antibody to the extent of 0.06%, 0.13%, and 0.65%, respectively. Serum concentrations of 3,5-T2 were measured in 62 healthy controls and 4 groups of patients with nonthyroidal illness, i.e. patients with sepsis (n = 24), liver diseases (n = 23), head and/or brain injury n = 15), and brain tumors (n = 21). The mean serum level of 3,5-T2 in the healthy subjects was 16.2 +/- 6.4 pmol/L. Concentrations of 3,5-T2 were significantly elevated in patients with sepsis (46.7 +/- 48.8 pmol/L; P < 0.01), liver diseases (24.8 +/- 14.9 pmol/L; P < 0.01), head and/or brain injury (24.1 +/- 11.3 pmol/L; P < 0.05), and brain tumors (21.6 +/- 4.8 pmol/L; P < 0.01). In all 4 patient groups, serum levels of T3 were significantly reduced, confirming the existence of a low T3 syndrome in these diseases. Serum concentrations of 3,5-T2 were significantly elevated in patients with hyperthyroidism (n = 9) and were reduced in patients with hypothyroidism (n = 8). The levels of T4, T3, and 3,5-T2 were measured in normal human tissue samples from the pituitary gland and various brain regions and in brain tumors. In normal brain tissue, the concentrations of 3,5-T2 ranged between 70-150 fmol/g, and the ratio of T3 to 3,5-T2 was approximately 20:1. In brain tumors, however, T3 levels were markedly lower, resulting in a ratio of T3 to 3,5-T2 of approximately 1:1. Recent findings suggest a physiological, thyromimetic role of 3,5-T2, possibly stimulating mitochondrial respiratory chain activity. Should this prove to be correct, then the increased availability of 3,5-T2 in nonthyroidal illness may be one factor involved in maintaining clinical euthyroidism in patients with reduced serum levels of T3 during nonthyroidal illness."
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