You just learned from your doctor that you need surgery. Thankfully you’ve got good medical coverage. But how many details about your condition should you share with your employer?

"Although you often need to talk with your benefits department about upcoming surgery in order to obtain approval for payment, that information is confidential and should not be shared with your manager," says career management coach and former HR director Bettina Seidman. "A request for time off for sick leave is all that is necessary."

Still, under certain circumstances a supervisor can legally ask a staff member medical questions, according to JustAnswer.com legal expert Paul Moretti. "The employer has a right to be aware if an employee has some condition that could flare up while the employee is at work," he says.

"Also, when an employee makes a request for leave under the Family and Medical Leave Act and/or a request under the Americans with Disabilities Act, the employer is entitled to get the medical records of the employee proving their qualifications under these acts," Moretti says.

The Family and Medical Leave Act allows anyone who works for a company with more than 50 employees to take up to 12 weeks of "job-protected, unpaid leave" for a serious medical condition, the birth or adoption of a child, or to care for an immediate family member who has a serious health problem.

The Americans with Disabilities Act (ADA) "requires that employers make reasonable accommodation to the known physical or mental limitations of otherwise qualified individuals with disabilities," according to the Justice Department. The ADA’s guidelines apply to organizations with more than 15 employees.

But the ADA leaves the definition of a disability open to interpretation, stating only that it includes "a physical or mental impairment that substantially limits one or more major life activities."

Moretti says that once a company has acquired sensitive personal information about one of its employees, it "places a duty of confidentiality on the employer. What this means is the employer cannot disclose this information without consent of the employee – other than the reasons for which it was gathered – and if the employer does release this information for unauthorized reasons, the employee can sue the employer for the breach of the duty of confidentiality."

Personal information that’s not related to a medical condition or disability can be equally touchy.

Your sexual orientation, financial situation, career goals, religious beliefs, and family history are among the private topics that potentially can interfere with your work environment, says human resources veteran Sheila Wyatt.

"There are still a number of people who, as employers, have not been able to eliminate all their biases or prejudices," she points out.

That close-mindedness can extend to co-workers as well, even those you consider friends who would never reveal what they know about you.

"In general, remember that your co-workers are just that; they are not your best friends, and their agendas may not coincide with yours," Seidman says.

Author and university professor Antonio Vianna, who spent more than 25 years as an HR professional, suggests a simple way that employers and employees might avoid all confidentiality problems: "Do not ask and do not share any information that does not directly relate to being able to perform the job."