Purpose: Masked hypertension (MH) is the association of normal office blood pressure (BP) with high ambulatory or home BP. This condition is associated with increased cardiovascular target organ damage, as true hypertension. Because the relation with hypothyroidism is controversial, we investigated it in a pilot longitudinal and controlled study.
Methods: We consecutively enrolled 64 newly diagnosed hypothyroid patients, 38 subclinical (s-HYPO), and 26 overt (o-HYPO). The control group consisted of 50 euthyroid subjects seen at outpatient clinics. All participants underwent office and 24-h ambulatory BP measurement.
Results: BP monitoring revealed a higher prevalence of MH both in s-HYPO (26.3 %) and in o-HYPO (15.4 %) than in euthyroid subjects (10 %, p = 0.05); true hypertension also was more frequent in o-HYPO (11.5 %) and s-HYPO (10.5 %) than in controls (8 %, p = 0.03). The odds ratio for hypertension versus normotension confirmed a significantly increased risk of MH in hypothyroid patients versus euthyroid subjects (3.29, 1.08-10.08; p = 0.02). In a subgroup of patients reevaluated after restoration of euthyroidism, an improvement of BP profile was observed, especially in s-HYPO subgroup, with a decreased prevalence of MH (from 25 to 10.7 %) and true hypertension (from 10.7 to 3.4 %).
Conclusions: Hypothyroidism may be an important predictor of higher BP values, with an increased risk of MH. Because MH is a cardiovascular risk and can be reversed by thyroid hormone replacement, its presence should represent an indication for thyroid hormone replacement therapy also in patients with s-HYPO.
Keywords: 24-h Blood pressure monitoring; Hypertension; Hypothyroidism; Masked hypertension.