A Santa Monica doctor who touted a controversial menopause therapy on the Oprah Winfrey Network and received testimonials for her work from such celebrity patients as model Cindy Crawford and actress-author Suzanne Somers has been disciplined by California’s medical board for gross negligence.

This story also ran on People.com . This story can be republished for free ( details ). In a settlement approved late last month, the Medical Board of California put Dr. Prudence Hall on probation for four years, faulting her for being “unaware” of potential risks posed by the plant-based hormones — including cancer — and failing to monitor her patients properly.

Hall used numerous hormones to treat two women, according to the board, missing an aggressive uterine cancer in one patient and treating the other based on an “incorrect diagnosis in a manner such that [Hall] stood to gain financially.”

“My jaw was on the floor. This is just egregious,” said Dr. Jen Gunter, a San Francisco Bay Area OB-GYN who reviewed the medical board’s report. “You hear about all these self-described functional medicine doctors providing these treatments. Never in my wildest dreams did I think it would be in this ballpark.”

A statement issued by Hall’s publicist Monday did not address the specifics of the board’s findings but generally defended the doctor’s results and commitment to patients.

“Dr. Hall continues to devote her career and life to helping patients achieve optimal health and wellness,” the statement said.

“She utilizes advances in modern medicine plus proven natural therapies. Safely incorporating results of the latest medical research has allowed her to achieve exceptional results for her patients.”

The statement added that Hall “joins respected physicians worldwide who are also using” this type of hormone therapy.

The hormone therapies prescribed by Hall are supposedly customized to individual patients’ needs and are generally not approved by the Food and Drug Administration. They are known as “bioidentical” because their molecular structure is the same as the natural hormones found in a woman’s body, including estrogen and progesterone.

Hall has claimed to have treated more than 40,000 patients with them over 30 years. Under the terms of her settlement with the board, she is no longer allowed to promote herself as a specialist in hormone therapy, an OB-GYN or an endocrinologist, and she must submit her medical practice to oversight by an outside physician who will report to the board. She is allowed to continue treating women for menopause management and other health issues.

Her case stands as a possible warning to many other physicians and providers who have embraced such unproven hormone treatments. Popularized by testimonials from celebrity women, these made-to-order hormones are used by up to 2.5 million women in the United States, according to one study.

Representatives for Crawford and Somers said they chose not to comment at this time.

Hall has been hailed by supporters as a “pioneer” in this type of personalized bioidentical hormone therapy, appearing on national television and infomercials and promoting such treatments as a virtual fountain of youth.

“It’s not about age; it’s about how healthy your hormones are,” Hall told Sarah Ferguson, the Duchess of York, in a conversation on the Oprah Winfrey Network in 2011. “It’s new to think we don’t have to grow old and grow ill.”

In her appearances, Hall offers an appealing message to women entering their 50s and 60s who are looking for “natural” relief from hot flashes, night sweats, loss of libido, aging skin or other concerns.

The hormone treatments she provides are “like water to a plant,” Hall told Somers on an episode of Somers’ television program, “The Suzanne Show.” “How could water be bad for a plant? … Hormones do not cause cancer.”

Dr. David Gorski, a surgical oncologist, professor of surgery at Wayne State University School of Medicine and a longtime critic of unproven alternative medicine, rejected Hall’s analogy. “I’m not a gardener by any stretch of the imagination,” he said, “but even I know that too much water can kill a plant.”

Many other clinicians and researchers say there’s no evidence to back up the claims by Hall and other doctors that these customized treatments are more effective or safer or that they act any differently in the body than FDA-approved hormone replacement therapies.

Some bioidentical hormones, unlike the ones primarily used by Hall, are FDA-approved. They are manufactured in pharmaceutical plants using standard formulas and have been shown to relieve menopausal symptoms — though they have not been tested in large, long-term trials — according to a report in Harvard Women’s Health Watch.

The customized therapies used by Hall and other doctors are mixed in compounding pharmacies and generally are not tested for safety and efficacy, according to Harvard Women’s Health Watch and other reports.

Compounded bioidenticals are big business. In 2013, U.S. sales of these products were estimated in one study at $845 million, compared with a $3.7 billion market for traditional, FDA-approved hormone replacement medications.

“There’s a definite concern that for some women they may be dangerous,” said Dr. Janet Pregler, director of the Iris Cantor-UCLA Women’s Health Center. “Often these [hormones] are presented as risk-free, when we as physicians know that nothing you put in your body is risk-free.”

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Women flocked to bioidentical hormone treatment after the Women’s Health Initiative, a massive federally funded study on a widely used hormone replacement therapy for menopausal women, was halted prematurely in 2002 over concerns about an elevated risk of breast cancer, heart disease and stroke.

Hall, according to medical board investigators, put a patient with a family history of uterine cancer on a regimen of bioidentical hormones after the woman complained of “zero libido” and menstrual migraines. She also prescribed iodine and two adrenal hormone supplements. The patient started to bleed — a potential warning sign of uterine cancer — but Hall prescribed her more hormones, according to the medical board.

Ultimately, the patient developed a cancerous mass in her uterus — but board investigators alleged that Hall failed to detect it, after performing ultrasounds on the patient that she was not certified to analyze. She charged the patient $7,000 over three years for the treatment, according to the board.

In the two cases for which she was disciplined — which occurred between 2011 and 2015 — the medical board found that Hall treated women who were not yet in menopause but whom she incorrectly diagnosed as being in perimenopause. Those are the years immediately before menopause that can create uncomfortable symptoms such as hot flashes and low libido. Their lab tests showed hormone values within normal limits, the board said.

The second patient had numerous other conditions including diabetes and a history of psychiatric disorders, according to the board. The board said Hall diagnosed the patient with hypothyroidism when no clinical evidence supported such a diagnosis — and that later aberrations that surfaced in lab testing had actually been caused by the physician’s treatment.

Hall presented herself to patients as a specialist in “hormone balance,” or endocrinology,” but does not have any post-medical school training by an accredited fellowship in either medical or reproductive endocrinology, according to the board.

It’s not the first time California’s medical board has disciplined a doctor for prescribing such bioidentical hormones. In 2009, the board put Dr. Michael Platt of Rancho Mirage on five years’ probation after charging him with negligence and incompetence for his treatments of several patients. The doctor, author of “The Miracle of Bio-identical Hormones,” later was forced to surrender his license.

Experts say such doctors take advantage of patients’ vulnerability as they age.

“We all fear getting older and loss of sexuality, and the way society makes women feel, women are more vulnerable to it, for sure,” said Gunter, the Bay Area OB-GYN. “I don’t blame the patients for going to the doctor and putting trust in them. I blame the doctors for saying this can somehow help them.”

Sheila Cosgrove Baylis of People magazine contributed to this report.

KHN’s coverage of these topics is supported by California Health Care Foundation and The David and Lucile Packard Foundation