“Your body doesn’t have the energy it needs ... You create antibodies that attack your glands,” Saldana, 38, told the magazine.
The couple have twin 1-year-old sons, and Saldana also has several movie projects lined up, including follow-ups to “Avatar,” “Guardians of the Galaxy” and “Star Trek Beyond,” which is out today.
The diagnosis has meant a major life adjustment, Saldana said in the interview.
“I had a great time in my twenties,” she said. “Then your doctor says you’re losing calcium in your bones ... I would hear those conversations with my mom and grandma, thinking I’d never get there. I’m going to live forever! But all of a sudden it hits you.”
ABC News Chief Women's Health Correspondent, Dr. Jennifer Ashton, said the symptoms of Hashimoto's thyroiditis and other thyroid disorders can be "profound" and "can affect everything head to toe."
"Some of the most popular ones, or more common ones, for Hashimoto's are fatigue, weight gain, you can see menstrual irregularities, irregular periods, or even constipation," she said.
Ashton added that people who experience "a number" of the symptoms for a "persistent amount of time" should go to their doctor for a blood test.
"Specifically, you have to look for thyroid antibodies," she said.