Study shows that suppressed TSH minimally affects heart health

[holyshedballs]

Minimal Cardiac Effects in Asymptomatic Athyreotic Patients Chronically Treated with Thyrotropin-Suppressive Doses of L-Thyroxine*

L. E. SHAPIRO, R. SIEVERT, L. ONG, E. L. OCAMPO, R. A. CHANCE, M. LEE,

M. NANNA, K. FERRICK, AND M. I. SURKS J Clin Endocrinol Metab 82: 2592–2595, 1997

ABSTRACT

Biondi, Fazio, and colleagues recently reported that long term T4 treatment to suppress serum TSH markedly affects cardiac function. T4-treated patients had more symptoms [12.2 6 3.9 (6SD) vs. 4.2 6 2.3 by quantitative questionnaire], higher mean heart rate, increased incidence of atrial extrasystoles, increased interventricular septal thickness and left ventricular mass index (LVMi), and significant diastolic dysfunction. The severity of cardiac abnormalities was highly correlated with scores of a rating scale used for assessing symptoms of thyrotoxicosis. We have duplicated their studies in 17 athyreotic patients (mean age, 45 6 10 yr; range, 27–63 yr) without heart disease or hypertension whose dose of T4 was titrated to suppress serum TSH to less than 0.01 mU/mL. The mean duration of T4 treatment was 9.2 6 5.4 yr. Controls were healthy volunteers matched for sex and age (63 yr). The mean T4 dose was 2.860.9mg/kg (0.192 6 0.058 mg/day). By questionnaire, patients had minimal symptoms, although their symptom score was significantly greater than the control value (4 6 3 vs. 2 6 1; P , 0.05; maximum score, 36).

No differences in mean heart rate or in atrial or ventricular extrasystoles were noted. In patients, indexes of systolic and diastolic function and interventricular septal thickness were similar to control values. The mean LVMi was normal in both groups. However, the mean LVMi in patients (117 6 35 g/m2) was higher than that in controls (92 6 31; P , 0.05). In conclusion, patients were minimally affected by TSH-suppressive doses of T4. They had few symptoms and no increase in extrasystoles or basal heart rate. Based on current knowledge, the increase in LVMi observed in patients without associated significant systolic or diastolic abnormalities does not have clinical or prognostic importance. Therefore, in the absence of symptoms of thyrotoxicosis, patients treated with TSH-suppressive doses of L-T4 may be followed clinically without specific cardiac laboratory studies.

[helvella Administrator]

The paper is available here:

academic.oup.com/jcem/artic...

[Hidden in reply to helvella]

Thank you I have just printed this off for future reference.

[SilverAvocado]

Quite a strange research design to compare the patients to healthy controls, and then say it's the TSH status of the patients that's being studied!

Looks like a useful paper, though

[SilverAvocado in reply to SilverAvocado]

Having read the full paper, I think the title and abstract are a little misleading. This reads more like a masterclass in how to treat with T4 monotherapy, and a detailed side by side comparison of heart health markers for T4 treated parents and healthy controls. I also enjoyed the kindly, slightly paternal protective tone the author takes with regard to their set of treated patients.

It shows that the T4 treated patients have almost identical heart measures to the controls. A few ambiguous measures come up as statistically significant (although when doing a huge number of measures, like they are, you do start to expect some to come up as significant). When looking at the charts of the data, the patient group's figures are a tiny bit worse for most measures. Hardly any were statistically significant, but also the sample size is 17, which is very small, so it's harder to get a significant result.

This is a hugely useful paper for anyone treated with T4 monotherapy, and to an extent for anyone running a suppressed TSH (especially as they emphasise it so much as the title), and for anyone whose doctor has pressured them to reduce a dose or denied an increase due to spurious arguments about heart health.

[holyshedballs in reply to SilverAvocado]

its a few hours since i read it - I'm at work now so from memory but another thing to bear in mind is it says there were no differences in ATRIAL systoles.

it is a good paper to get the balance right no hypo symptoms and no hyper symptoms.