Hypothyroidism as a Potential Risk Factor in Hypertensive Patients

There have been previous studies examining the association between thyroid dysfunction and cardiovascular disease. Hypothyroidism is related to an increased risk of functional cardiovascular abnormalities, particularly for hypertension. The aim was to characterize the prevalence of hypothyroidism as a risk factor for arterial hypertension in a community-based study in San Luis, Argentina. Cross-sectional, retrospective and descriptive studies were designed. A total of 1,023 individuals were recorded at a cardiologic center (2006- 2008). Data abstracted from clinical history included: age, sex, hypertension (HTA >140/90 mm Hg), and serum thyroid function tests: TSH, T4 and T3. The investigation involved 698 patients with HTA (74.2% women), 367 with hypothyroidism (81.5% women) and 247 with hypothyroidism-HTA (79,8% women). Ages ranged from 22 to 92 years (mean: 49.9± 11.9) and mean weight 84.3±17.0 kg. Age was positively correlated with body weight (r=+ 0.312, P=0.003). TSH mean: 7.67±1.6 µIU/ml (Men: 6.28±1.2 µIU/ml, Women: 7.92±2.1 µIU/ml). The mean systolic (SBP) and diastolic blood pressure (DBP) were 160.8±25.4 mm Hg and 98.8±13.9 mm Hg, respectively. Increasing SBP-DBP for range of TSH was studied. The positive association between TSH and SBP (r:+0.155,P=0.042) were found. The association between age (four categories) versus SBP in hypothyroidism patients (r=+0.267, P=0.0001) and the highest percentage was in the age range 51-60 years. DBP was also positively associated with age (r=+0.200, P= 0.0001), highest percentage in age range 41-50 years. There was an important increase in SBP (160.75±19.39-175.43± 21.00 mmHg) and TSH (3.71±2.05-12.06±9.23 µUI/mL) in hypothyroid patients by age. DBP was highest in the 4th decade (104.70±11.87 mmHg). The positive association between TSH hypothyroidism-HTA and age were found (r:+0.353,P=0.0001). Serum T4 (7.78±2.40-6.75±2.15 µgr/dL) and T3 (1.24±0.35-0.88±0.26 ng/mL) decreased with age. High prevalence of hypothyroidism in our hypertensive patients was detected (20.8% and 5.6% subclinical). Decrease of serum T4 and T3 suggest the lack of blood pressure regulation which could be responsible for the hypertensive state. We found a positive association between TSH and SBP that could have implications for cardiovascular health. These findings indicate that hypothyroidism may be an important predictor of higher mean SBP. In conclusion, in these population patients we found a close association between hypertension and hypothyroidism.