Im 25 healthy/in-shape yet blood pressure is always high (systolic 140-143). i do have a mild underactive thyroid (tsh 5.3). could they be related?

Get treatment: Whether the two issues are related on not, both warrant being treated. Start with you primary care provider and if need be get consultations with endocrinologist and cardiologist. Wish you good health! - Have a diet rich in fresh vegetables, fruits, whole grains, milk and milk products, nuts, beans, legumes, lentils and small amounts of lean meats. Avoid saturated fats. Drink enough water daily, so that your urine is mostly colorless. Exercise at least 150 minutes/week and increase the intensity of exercise gradually. Do not use tobacco, alcohol, weed or street drugs in any form. Practice safe sex, if you have sex.