What body functions are affected by hashimoto's thyroiditis?

All of them.: While the inflammation (the -itis part of thyroiditis) affects only the thyroid, if this causes the thyroid levels to drop, every tissue in the body can be affected - simplistically this can cause a slow down of the heart, the GI tract, the liver, the muscles, and the brain. Because the cells are slower to convert food energy to heat or work energy there is less energy to get things done.

Purely depends on: Whether the thyoiditis produces too much or too little thyroid hormone too much- shaky, nervous, jittery, hair loss frequent bowel movements, sweaty, fast heart beats too little hormone- constipation, dry skin, fatigue, hair loss normal hormone level= no sx's due to the thyroiditis.