MADRID — On April 11, new broadcaster Cuatro threw a “House” party, a frosh season finale featuring viewers’ two favorite segs — the pilot “Paternity” and “Three Stories.”

Cuatro should celebrate. Airing Tuesday primetime since Jan. 24, medical drama “House” doubled, sometimes tripled its average 5.4% share from the get-go.

March 28’s episode, “Love Hurts,” took a 15.1% share and 2.6 million viewers, and was the timeslot’s numero uno for 16-54s, per Cuatro.

Spain’s “House” boom is no slam dunk.

U.S. movie blockbusters more or less replicate Stateside success in Spain. But U.S. TV watercoolers can turn into turkeys.

The second season of “Desperate Housewives” was down April 18 to 11.6% (2 million viewers), a disappointing 7.6 points below TVE-1 averages.

The jury’s still out on “Lost.” It started out reasonably well here, averaging a 19% share (2.4 million viewers) last summer — but that’s merely average for TVE-1 during the warm-weather months, when there’s much less competition.

It remains to be seen how season two will do, which TVE-1 will air in full season primetime.

This leaves “House” looking like it could be the fourth true-blue hit Yank series in 10 years, after “CSI,” “The Simpsons” and “Ally McBeal.”

“A program’s success should be judged by how much it increases a channel’s audience and how much it costs,” says Glen Spencer Chapman, at Ibersecurities.

Cuatro picked up “House” before tyro rival La Sexta moved on “The Sopranos,” paying a reported $80,000 an episode and firing up prices for U.S. series.

So why is Spain warming to “House”?

“The writing is marvelous, magic. You won’t find anything better in movies today,” says Cuatro programming director Fernando Jerez.

That doesn’t explain the skein’s mixed Euro reception.

Per Paris-based research company WIT, it’s got Brit hearts pulsing, doubling terrestrial upstart Five’s 6% norm. Its Brit star Hugh Laurie may have something to do with that.

Show was anemic airing last summer on Italy’s Italia 1; and is off the broadcaster cardiograph in France, airing on TPS digital satellite channel TF6.

Cuatro wisely back-to-backed “House” segs. Spanish are chaotic and convivial. Even at 10 p.m. friends pop in, children don’t make it to bed. Viewers need two bites to take in a densely false-trailed procedural.

Per Eduardo Garcia Matilla, prexy of research firm Multimedia Corp., “House” attracts “permissive liberals and generation X-ers.”

Yet “House” largely made good in Spain, both Jerez and Matilla insist, because of its lead character, the spiky and uncompromising doctor Gregory House.

Spain encourages individual genius like painter Pablo Picasso. Disastrously governed for centuries, Spaniards buck the rules. Ditto the doctor. Spanish humor is darkly grotesque. Locals can warm to a Vicodin-popping, crippled doctor heroically seeking the truth.

And Spaniards love straight-talking Americans of austere emotions, which it takes a world to open (think Clint Eastwood, western heroes).

So House is their hombre.