Story highlights Manning is serving a 35-year sentence for espionage

She announced that she is female the day after her sentencing

Manning is suing to receive hormone treatment "to express her female gender"

Chelsea Manning, convicted of espionage and imprisoned at Fort Leavenworth, has filed a lawsuit in federal court, claiming she "has been denied access to medically necessary treatment" for her gender disorder.

The inmate once known as Bradley Manning announced in August 2013 , the day after her court sentencing, that she is female. Manning is suing to follow grooming standards such as growing her hair longer and using cosmetics, and to receive hormone treatment "in order to express her female gender," said the suit filed Tuesday in district court in Washington.

"She brings this action to compel defendants [Defense Secretary Chuck Hagel and the federal government] to treat her serious medical needs consistent with their obligation under the Constitution," said the suit. If the requests are denied, said Manning's lawyers, she "will suffer continued pain, depression and anxiety and is at an extremely high risk of self-castration and suicidality."

A Kansas judge in April granted the former Army intelligence analyst's request to formally be known as Chelsea Elizabeth Manning.

"I've been working for months for this change, and waiting for years," she said in a statement at the time. There was no immediate reaction from the government on Manning's new lawsuit. The Obama administration is expected to give a written response to the lawsuit in coming weeks.

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Manning is serving a 35-year sentence at Fort Leavenworth, an Army prison in eastern Kansas.

She was convicted last year of stealing and disseminating 750,000 pages of documents and videos to WikiLeaks in what has been described as the largest leak of classified material in U.S. history. Manning was found guilty of 20 of the 22 charges against her, including violations of the U.S. Espionage Act.

At the time of her announcement that she planned to live as a woman, Manning asked for support and said she wanted to begin hormone therapy as soon as possible.

"I requested that the military provide me with a treatment plan consistent with the recognized professional standards of care for trans [gender] health. They quickly evaluated me and informed me that they came up with a proposed treatment plan.

"However, I have not yet seen their treatment plan, and in over eight months, I have not received any response as to whether the plan will be approved or disapproved, or whether it follows the guidelines of qualified health professionals," Manning said. She said that lack of treatment continues to this day.

Her supporters had indicated a lawsuit would be a likely option.

Manning said she was diagnosed in 2010 with gender dysphoria, which her lawyers describe as "the medical diagnosis given to individuals whose gender identity-- their innate sense of being male or female-- differs from the sex they were assigned at birth, causing clinically significant distress."

Prisoners and male-to-female transsexuals, like Manning in particular, are at high risk of self-mutilation including castration, according to her legal team from the ACLU.

Manning said Army officials have been too slow in responding to her requests for clinical treatment, grooming preferences and ultimate transfer to a civilian prison where she believes those requests would be better addressed.

"No decision to transfer Pvt. Manning to a civilian detention facility has been made," said Pentagon press secretary Rear Adm. John Kirby in May, "and any such decision will, of course, properly balance the soldier's medical needs with our obligation to ensure she remains behind bars."

There was no indication when the district court would try the case or render a decision. The case is Manning v. Hagel (14-cv-1609).