A dangerously underweight and dehydrated woman who had undergone scans that showed dozens of pills in her stomach was discharged from an Adelaide hospital nine days before she died from laxative abuse, a coronial inquest has heard.

Claudia La Bella, 28, weighed just 35 kilograms when she died on June 29, 2014, from complications associated with laxative abuse.

However, at the time of her death, her husband, family and friends thought she had died from ovarian cancer.

In 2012, Mrs La Bella falsely told her loved ones that she had been diagnosed with terminal ovarian cancer and only had a few years to live.

She claimed she needed to take laxative tablets as part of her treatment to flush the toxins from the chemotherapy out of her system.

In her opening address, counsel assisting the coroner Kathryn Waite said Mrs La Bella was taking up to 800 laxative tablets a day.

"She had been witnessed by families and friends taking handfuls of tablets at a time," she said.

The inquest, before coroner Mark Johns, heard Mrs La Bella and her husband John La Bella would spend about $500 per week buying the laxatives from their local chemist.

In his evidence to the court, Mr La Bella said his wife would attend appointments she said were for cancer treatment but she would never allow him to come with her.

"I trusted her, she's an adult, not a child, I took her word," he said.

He said he had picked her up from hospital on a number of occasions because she told him she could not drive after having surgery.

Mr La Bella told the court he would make weekly trips to Chemist King at Hectorville to purchase handfuls of boxes of the laxatives his wife requested.

"There was always a supply in the pantry area," he said.

"In the beginning no more than two or three [packets of laxatives were in their pantry], as it progressed, 15."

La Bella was frail, skeletal at time of hospital visit

The court heard the Dulcolax laxatives she was consuming were bought in packs of 200, which had a recommended daily dosage of two to three tablets per day, for no more than a week.

On June 18, 2014, Mrs La Bella was admitted to the Royal Adelaide Hospital with severe abdominal pain, vomiting and diarrhea.

Ms Waite told the inquest Mrs La Bella, who had never been diagnosed with anorexia, was skeletal, severely underweight and dangerously dehydrated.

"Witnesses note that she is frail and can barely walk, she was dehydrated," she said.

A CT scan was performed which revealed "dozens of partially digested pills" in her stomach, which Mrs La Bella claimed were painkillers.

Ms Waite said the following day Mrs La Bella told her treatment team she wanted to self-discharge because she wanted to go home.

"The doctor had serious concerns and strongly advised against it but ultimately he sees no reason to detain her under the powers he can implement using an inpatient treatment order," she said.

"He sees no objective evidence of a mental illness posing risking of harm to herself or others.

"However, Mrs La Bella is required to sign a risk consent form prior to being allowed to discharge herself in such a dangerous state of health."

Family did not know real cause of death

The court heard she was given a treatment plan on her discharge and told to follow up with her GP.

"It would appear during this hospital stay no-one has mentioned cancer," Ms Waite said.

"Mrs La Bella's family is frequently with her, there is no evidence that the family speak with the doctors nor that they are ever taken aside by the treating team to discuss Mrs La Bella's condition."

Mr La Bella told the court it was not until he read the coroner's report after his wife's death that he found out the real reason behind her death.

During the inquest, the court will hear evidence from Mrs La Bella's GP, the doctor who treated her at the RAH as well as the pharmacist and retail manager at Chemist King.

Ms Waite said expert psychiatrist Dr Maria Naso, who has reviewed the case, would tell the court had Mrs La Bella been detained at the RAH she would not have died when she did.

"Mrs La Bella had been discharged from hospital close to death, she was a young woman, 28 years old with no diagnosis as to what was causing her decline," she said.

She said Dr Naso had found in addition to anorexia, Mrs La Bella suffered from the factitious disorder Munchausen syndrome where a person repeatedly acts as if they have an illness when they are not really sick.