The Johns Hopkins University Hospital and School of Medicine has announced plans for an $83.9-million construction and renovation program at its East Baltimore campus, the second phase of a massive rebuilding project that will either renovate or replace the entire 90-year-old medical facility.

Included in the project are plans for a psychiatry and neurosciences center that would make Hopkins the first major medical institution in the nation to bring psychiatry, neurology and neurosurgery together under one roof.

The $37.5-million center will occupy most of a nine-story tower to be constructed of a nine-story tower to be constructed on the site of the hospital's Women's Clinic and will become a regional facility for treatment of people with psychiatric and central nervous system disorders. The Women's Clinic building will be torn down.

Plans also call for a combined unrology and nephrology institute combining the surgical specialty of urology with its medical counterpart, nephrology in a single institute for the treatment of renal disorders - those involving the kidneys, bladder, prostate and related organs.

That institute will be relocated in a completely renovated Marburg building, one of the three original Hopkins structures on the National Register of Historic Buildings.

Also included in the renovation program are a new heart center that will bring together pediatric and adult cardiologists and cardiac surgeons, their clinics and equipment and a new preclinical teaching laboratories, lecture halls, a multimedia learning center and a dining and commons area for student and faculty.

Announcement of phase two of the Hopkins renovation program comes a year after the completion of phase one a $55-million project that was begun in the early 1970s. Among the major elements in that plan were a new cancer center, a patient tower and a teaching tower, containing offices and conference rooms for staff members.

Plans for the massive rebuilding effort orginated in the late 1960s when the hospital and school of medicine seriously considered abandoning its inner city location to relocate in the suburbs. After some debate, officials decided to keep the medical facility at its original location, but when they did, it became apparent that most buildings would either have to be substantially renovated or razed and replaced.

Approval for phase two was recently granted by the Maryland Health Planning and Development Agency, and construction is expected to start in the spring. Approximately $53.3 million of the cost will be paid by the hospital while $30.6 million will be covered by the university.

Among the other major segments of the building program are expansion of surgery and outpatient facilities, doubling the space in the infant special care unit at the Children's Center renovation or replacement of all the hospital's 17 general operating rooms, enlargement of facilities for rehabilitation medicine and the department of anesthesiology, construction of new autopsy rooms and modernization of laboratories in the pathology building.

One of the nation's most prestigious medical schools and hospitals, Johns Hopkins is unusual in that it provides more than a quarter of its total day care to people who live outside the area of Baltimore and its suburbs.

Despite the extensive renovation officials said the hospital's patient capacity will be slightly reduced in an effort to keep operating costs down. Currently the hospital has 1,097 beds. The medical school enrolls 400 MD candidates and 142 doctorate and master's degree candidates. There is a full-time faculty of 668.