Hello Sir Yes they can be interrelated....An under-active thyroid may disable the LES(lower esophageal sphinctor), allowing food and digestive acids to re-enter the esophagus from the stomach. In addition, hypothyroidism has been shown to delay gastric emptying, which allows more acid to flow upward into the esophagus..fallow bellow advices with your hypothyroidism medications try eating several small meals instead of three large ones whenever you can...Avoid foods that irritate your stomach, especially those that are spicy, acidic, fried or fatty... avoid coffee,tea etc... Stress may make your gastritis symptoms worse...Stress may be hard to avoid, but you can learn to cope with it. If you have trouble relaxing, consider calming activities, such as meditation, yoga etc...sleep with head raised position and have dinner at least 2 hours before sleep..take over the counter medications with above..consulting doctor if symptoms persists. Regards