Thyroid hormone and blood pressure

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The role of thyroid hormone in blood pressure homeostasis: evidence from

short-term hypothyroidism in humans.

http://www.ncbi.nlm.nih.gov/pubmed/11994331?dopt=Abstract

Fommei

E, Iervasi

G.

Source

National Council of Research, University of Pisa, Italy.

Abstract

Arterial hypertension is known to be frequently associated with thyroid

dysfunction, with a particularly high prevalence in chronic hypothyroidism.

However, to our knowledge no comprehensive study addressed causal mechanisms

possibly involved in this association. We here report the physiological

relationships between blood pressure and neuro-humoral modifications induced by

acute hypothyroidism in normotensive subjects. Twelve normotensive patients

with previous total thyroidectomy were studied. Ambulatory 24-h blood pressure

monitoring was performed, and free T(3), free T(4), TSH, PRA, aldosterone,

cortisol, adrenaline, and noradrenaline were assayed 6 wk after oral L-T(4)

withdrawal (phase 1) and 2 months after resumption of treatment (phase 2).

During the hypothyroid state (TSH, 68.1 +/- 27.7 microIU/ml; mean +/- SD),

daytime arterial systolic levels slightly, but significantly, increased (125.5

+/- 9.7 vs. 120.4 +/- 10.8 mm Hg; P < 0.05), and daytime diastolic levels

(84.6 +/- 7.9 vs. 76.4 +/- 6.8 mm Hg; P < 0.001), noradrenaline (2954 +/-

1578 vs. 1574 +/- 962 pmol/liter; P < 0.001), and adrenaline (228.4 +/- 160

vs. 111.3 +/- 46.1 pmol/liter; P < 0.05) also increased. PRA remained

unchanged (0.49 +/- 0.37 vs. 0.35 +/- 0.21 ng/ml.h; P = NS), whereas both

aldosterone (310.3 +/- 151 vs. 156.9 +/- 67.5 pmol/liter; P < 0.005) and

cortisol (409.2 +/- 239 vs. 250.9 +/- 113 pmol/liter; P < 0.02)

significantly increased. By using univariate logistic regression daytime

arterial diastolic values, noradrenaline and aldosterone were found to be

significantly related to the hypothyroid state (P < 0.02, P < 0.036, and

P < 0.024, respectively). In conclusion, our data show that thyroid

hormones participate in the control of systemic arterial blood pressure

homeostasis in normotensive subjects. The observed sympathetic and adrenal

activation in hypothyroidism, which is reversible with thyroid hormone

treatment, may also contribute to the development of arterial hypertension in

human hypothyroidism.

PMID:

11994331

[PubMed - indexed for MEDLINE]

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