Rapidly Acting Thyroid Hormones and Their Cardiac Action

Triiodothyroacetic acid in health and disease

“…However, relatively high TA 3 doses, up to 5 mg daily (~70 µg/kg/day), were needed to reduce serum cholesterol levels in these studies, with usually only transient effects (Oliver & Boyd 1957, Boyd & Oliver 1960). In non-controlled studies, at doses not affecting BMR, more episodes of transient thoracic pain and increased exercise intolerance have been reported in hypothyroid and euthyroid subjects independent of the TA 3 dose, which subsided after TA 3 withdrawal (Oliver & Boyd 1957, Ibbertson et al 1959, Boyd & Oliver 1960. In contrast to these early studies, Brenta and coworkers (Brenta et al 2003) already observed a reduction in cholesterol levels using a dose of 20 µg TA 3 /kg/day in healthy subjects.…”

“…Normalization of BMR is generally observed in a dose range of 50-75 µg/kg/day (Table 4). In general, the effects of TA 3 occur more rapidly compared to T 3 (Zondek et al 1956, Ibbertson et al 1959. Thus, TA 3 effectively restores euthyroidism in hypothyroid patients, but is less potent than LT 4 and LT 3 .…”

“…Mechelany and coworkers (Mechelany et al 1991) have shown that TA 3 reduced serum creatine kinase levels. TA 3 also increased urinary creatine levels in hypothyroid subjects, suggesting an increase in glomerular filtration rate (Lerman & Pitt-Rivers 1956, Rall et al 1956, De Graeff et al 1957, Ibbertson et al 1959.…”

“…In general, TA 3 doses of 10-30 µg/kg/day improved the myxedematous appearance and restored several parameters that reflect tissue TH status, including plasma cholesterol levels, urinary creatine excretion, electrocardiographic abnormalities and body weight, whereas no effect on BMR was observed (Lerman & Pitt-Rivers 1955, 1956, Trotter 1955, 1956, De Graeff et al 1957, Ibbertson et al 1959, Boyd & Oliver 1960. Normalization of BMR is generally observed in a dose range of 50-75 µg/kg/day (Table 4).…”

“…i.p., intraperitoneal; i.v., intravenous; s.c., subcutaneous; stim., TRH-stimulated. Oliver & Boyd (1957), Boyd & Oliver (1960), Medeiros-Neto et al (1980), Beck-Peccoz et al (1988), Lind et al (1989), Bracco et al (1993), Brenta et al (2003) ↓ Hypo ~10 µg/kg/day; 2-3 month Lerman & Pitt-Rivers (1955, 1956, Trotter (1955Trotter ( , 1956, Rall et al (1956), Zondek et al (1956), De Graeff et al (1957, Ibbertson et al (1959), Boyd & Oliver (1960), Hill et al (1960), Lerman (1961) Trotter (1955Trotter ( , 1956), Lerman & Pitt-Rivers (1956), Rall et al (1956), Zondek et al (1956), De Graeff et al (1957, Ibbertson et al (1959), Hill et al (1960), Boyd & Oliver (1960), Lerman (1961), Sherman et al (1997) Protein oxidation = Eu 45 µg/kg/day; 3 week Bracco et al (1993) (Continued) 234:2 and sleeping energy expenditure, presumably due to a reduction of endogenous TH production, whereas protein oxidation was unaffected (Bracco et al 1993). These parameters significantly increased in subjects treated with 2.4-4.8 µg LT 4 /kg/day (Bracco et al 1993).…”