Leah is a hard-working and serious female cell who wants to do what's right. She disliked Osmosis Jones at first, but she grew warm to him and started to care for him later on. Leah is very kind to her friends.
Osmosis Jones (movie)
She was first seen at her office where she told the mayor about Tom's campaign video and ask him about Frank's health.
Later on, she was sent to get a cold pill named Drix and while she's waiting, she notice that Osmosis was flirting with her, which she wasn't interested in and thought of him as a jerk.
She wasn't seen again until she was at the mayor's office where Drix and Osmosis came in and was curious about Osmosis's story (the one when he first saw a virus named Thrax).
She believes him and tells the mayor to cancel the trip so Frank will get better to be safe, but the mayor doesn't want to cancel the trip because of his re-election.
Later on, she was seen again after realizing that something is wrong and told the mayor that Osmosis was right about Thrax. Realizing that the mayor only care about his re-election rather than their life, she angrily left to find out and later got kidnapped by Thrax.
When she got kidnapped, Ozzy and Drix rescue Leah and confront Thrax who leaves Frank's mouth after causing Frank to sneeze using pollen bombs.
Ozzy is launched out after him by Drix when Ozzy and Thrax fight one of Shane's eyeballs and end up on Shane's false eyelashes, which she was wearing atop her natural ones, after she blinks.
During the fight, Thrax threatens to break his own record by killing Shane, but Ozzy tricks him into getting stuck on Shane's false eyelash and falling into a vessel of alcohol below where he dissolves.
During this time, the situation becomes even more dangerous when the temperature hits 108 degrees, causing Frank to go into cardiac arrest.
Just as doctors begin to give up, Frank is revived when Ozzy returns to Frank via one of Shane's crying tears with the DNA chain containing the missing hypothalamus chromosome.
Ozzy is reinstated into "Immunity" with full privileges, Ozzy and Drix are declared heroes with the Chief of Police giving Ozzy his job back.
While Osmosis was planning on extending Drix's time in Frank with the help from the hemorrhoid, Leah returns his affections and told him "Come here, baby. I'm still joneseń for little us osmosis."
Then, she kisses him on the lips which Osmosis was shocked at, but happily kissed back.
For some unknown reason, Leah does not appear in Ozzy & Drix and is replaced by Maria Amino.
Leah is the only female cell to be one of the main characters.
Leah bears a resemblance to Vicki Vale from Batman, part of the DC Universe.
Sherri Howard, Holly Robinson, Camryn Manheim, Paula Abdul, Nicole Kidman, Halle Berry, Cameron Diaz, the late Anna Nicole Smith, Julie Benz, Reese Witherspoon, Joely Fisher and Meg Ryan were all considered for the role of Leah Estrogen.
Osmosis Jones walks into the Chief's office and says "Brandy! I mean, Leah. Why are you here?" He is speaking to the mayor's aide Leah, who is voiced by Brandy Norwood. The flubbed line was acted so well that it was left in because it felt pleasingly funny.