Thyroxine alone may reverse hypertension
in some patients with hypothyroidism
(July 2002)
The background of
the study. Some patients with hypothyroidism have hypertension.
This study evaluated the pathogenesis of hypertension in patients
with hypothyroidism, and the extent to which it decreased during
treatment with thyroxine (T4) and combined T4 and calcium-channel
antagonist drug therapy (felodipine).
How the study was done. The main
study group consisted of 30 patients with hypothyroidism (mean serum
thyrotropin [TSH] concentration, 81 mU/L) and hypertension (mean
blood pressure, 160/109 mm Hg). Other study groups (all age- and
sex-matched) were 15 patients with hypothyroidism (mean serum TSH
concentration, 81 mU/L) and normal blood pressure (mean, 121/86
mm Hg), 15 patients with hypertension (mean blood pressure, 155/108
mm Hg) and normal thyroid function, and 30 normal subjects (mean
blood pressure, 125/78 mm Hg).
Blood pressure was measured at base line in all study subjects,
after treatment with T4 in the two groups of patients with hypothyroidism,
after treatment with felodipine in the patients with hypertension,
and also after the addition of felodipine in the 15 patients with
hypothyroidism and hypertension who remained hypertensive during
T4 therapy.
The results of the study. As compared
with the normal subjects, the patients with hypothyroidism and hypertension
and those with hypothyroidism alone had a lower heart rate and increased
vascular resistance to blood flow. The patients with hypertension
alone also had increased vascular resistance. The changes were reversed
during T4 or felodipine therapy, respectively, in the latter two
groups.
Among the 30 patients with hypothyroidism and hypertension, 15
had normal blood pressure during T4 therapy (mean blood pressure,
118/83 mm Hg). The other 15 patients had persistent hypertension
during T4 therapy (mean blood pressure, 151/105 mm Hg), and all
15 had normal blood pressure after felodipine therapy was added
(mean, 114/83 mm Hg).
The conclusions of the study. Patients
with hypothyroidism, especially those with hypertension, have increased
vascular resistance, which may be reversed by T4 therapy.
The original article. Dernellis
J, Panaretou M. Effects of thyroid replacement therapy on arterial
blood pressure in patients with hypertension and hypothyroidism.
Am Heart J 2002;143:718-24.
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