MTV did not have an immediate comment on Portwood or her condition, but the website said she had been hospitalized.
Radar later cited a police report, which read: "Late this morning (11:34 a.m.), Anderson [Ind.] Police responded to a call at a residence in the 1300 block of Pleasant Meadow Drive. According to the caller, 21-year-old Amber L. Portwood was depressed and threatening to end her life. The victim, who did not appear to be injured, was transported to a local medical facility for further evaluation."
A focal point of Portwood's role on the show has been the on-again-off-again relationship with her former fiance, Gary Shirley, who is also father of her toddler, Leah.
In December, the MTV reality star was charged with two felony counts of domestic battery, one felony count of neglect of a dependent and one misdemeanor count of domestic battery stemming from striking Shirley in front of their daughter.
She pleaded guilty to the felony counts of domestic battery last week and was sentenced to 2 years of probation. Her other charges were dropped as part of her plea deal.
In the third season, which begins July 5, the couple seems to be together again. (A source told Radar that Shirley had visited Portwood in the hospital.)
In the episode that MTV sent to TV critics for screening, Portwood is seen breaking up with another boyfriend, Chris, and later reconciling with Shirley.
"Teen Mom" is one of MTV's most popular series, averaging about 3 million viewers last season.