Background: Overt hypothyroidism is associated with elevation of diastolic blood pressure; however the association of subclinical hypothyroidism (SH) with arterial blood pressure (ABP) alteration is unknown.
Objective: The aim of the present study was to evaluate ambulatory blood pressure monitoring (ABPM), over 24 hours, in normotensive patients with SH in comparison to euthyroid (EU) normotensive individuals.
Methods: A cross-sectional study was performed with 50 participants (SH = 30 and EU = 20) that did not differ regarding risk factors for hypertension. The ABPM was carried out with a DINAMAPA TM monitor, using the oscillometric method validated by AAMI (Association for the Advancement of Medical Instrumentation) and by the BHS (British Hypertension Society).
Results: The mean serum TSH and FT4 were respectively 6.9 +/- 2.2 microUI/ml and 1.1 +/- 0.2 ng/dl in SH patients. Although there was no difference in the mean values of systolic and diastolic blood pressure between the two groups, there was a positive correlation between the mean values of diastolic blood pressure (DBP) and serum TSH levels in SH patients (r:0.477; p = 0.004). These correlations were detected at daytime (r:0.498; p = 0.002) and sleep-time (r:0.322; p = 0.032) measurements.
Conclusion: The blood pressure was not different between patients with or without SH; however, the results suggest that the progression of subclinical hypothyroidism to higher levels of TSH may increase the cardiovascular risk by increasing diastolic blood pressure.