(USA TODAY) -- There are numbers to track cholesterol and numbers to assess blood pressure, body temperature and weight. But can a number give an accurate read on your mental health?

The medical team behind a screening tool called Whats MyM3 says it can -- and it can tell if you're at increased risk for depression, anxiety disorder, bipolar disorder and post-traumatic stress disorder (PTSD).

WhatsMyM3 (originally My Mood Monitor) can help adults, even if not in treatment, "monitor their own symptoms and have a view of what's going on" with mood and anxiety, says psychiatrist Steven Daviss of M3 Information of Bethesda, Md. Daviss is chairman of psychiatry at Baltimore Washington Medical Center.

WhatsMyM3 is available as a mobile app ($2.99 for iPhone, iPad and Android) or free on the Web (WhatsMyM3.com). M3Clinician is a version for physicians. The company has no financial or other relationship with the pharmaceutical industry, says president Michael Byer.

About one in five adults have some sort of mental illness, the Substance Abuse and Mental Health Services Administration says, yet only about 60% of adults with mental illness get treatment each year.

Many of those who need treatment are seen in a primary-care setting, yet emotional health "never really comes up for discussion" and goes untreated, says psychiatrist Robert Post, former chief of biological psychiatry at the National Institute of Mental Health and one of the WhatsMyM3 developers.

All three versions use a 27-item questionnaire. Responses generate an individual score; 33 or greater indicates a significant risk of mood and anxiety disorders. Four subscores reflect risk for each of the four major conditions, Post says.

Although other mental health apps are on the market, they usually focus on just one area, such as depression, Post says, and may miss others, such as bipolar disorder or anxiety.

Some in the field already are using the tool. Mental Health America, an education and advocacy group, put Whats MyM3 on its website, says CEO David Shern, a psychiatrist. "It helps give you a normative sense of what's in bounds and out of bounds" for mental health. "That can be helpful for anybody who's curious about or worried about how they're doing."