ASSOCIATION BETWEEN THYROID DYSFUNCTION AND BLOOD PRESSURE CONTROL IN HYPERTENSIVE PATIENTS ATTENDING OUTPATIENT DEPARTMENTS

Abstract

Background: Thyroid dysfunction, particularly hypothyroidism, has been associated with changes in cardiovascular hemodynamics, including systemic blood pressure. In hypertensive individuals, underlying thyroid abnormalities may contribute to poor blood pressure control and increased cardiovascular risk. However, the extent of this correlation remains under-investigated in outpatient settings in Pakistan.

Objective:  To determine the correlation between thyroid dysfunction and blood pressure among known hypertensive individuals.

Methods:  A cross-sectional study was carried out at Department of Medicine, Dow University of Health Sciences (DUHS), Dr. Ruth K. M. Pfau Civil Hospital, Karachi, 3-6 months post CPSP synopsis approval. A convenient sample of 193 hypertensive patients, between the age of 18 and 80 years, on antihypertensive monotherapy at least for 1 year, were selected through non-probability consecutive sampling. Pregnant women were excluded. Demographic and clinical details were noted after taking an informed consent. The blood pressure has been measured 3 times at interval of 5 min after resting for 10 min, and has been taken the mean value of second and third readings. Serum TSH, FT3, FT4 and lipid profile, HbA1c and hemoglobin were measured from blood samples (Roche Cobas e411, ECLIA method). The data were input into Excel and analyzed in SPSS v26. Quantitative variables were expressed in mean ± SD or median (IQR), categorical variables as frequencies and percentages. Pearson correlation was employed for TSH and blood pressure correlation. Age, BMI, metabolic syndrome, renal function and the extent of medication adherence were adjusted for by stratification and multivariate regression. Statistical significance was considered as a p-value ≤ 0.05.
Results: Of the 193 hypertensive patients, the mean age was 55.8 ± 10.9 years and 52.8% were women. More than half of the participants (61.1%) had been hypertensive for more than 5 years and 84.5% were on antihypertensive drugs However, only 48.2% of these individuals had controlled hypertension. A known thyroid disease was present in 16.6% of them, and laboratory results showed subclinical hypothyroidism in 18.7%, overt hypothyroidism in 5.2%, and hyperthyroidism in 6.8% of patients. TSH was negatively correlated with FT3 (r = -0.155; P = 0.039), FT4 (r = -0.140; P = 0.059) and positively correlated with SBP (r = 0.0347; P = 0.003), and DBP (r = 0.182; P = 0.002). Sedentarism, diabetes (26.9%) and cardiac disease (12.4%) were common comorbidities.

Conclusion:  A significant positive correlation was found between TSH levels and both systolic and diastolic blood pressure in hypertensive patients, suggesting that thyroid dysfunction may influence blood pressure control. Routine thyroid function assessment could be beneficial in the comprehensive management of hypertension.