Now that Twitter has announced its filing for a planned IPO, we can all expect the scrutiny knob to be cranked up to the max. This is no doubt why Twitter has gone the confidential route, but that doesn’t mean analysts and the blogosphere at large won’t pick apart every aspect of the company possible from the inside out.

A day after the announcement, the company’s growth rate has already come into question.

Twitter announced that it hit 200 million monthly active users in December.

A far cry from Facebook’s over a billion, but nothing to shake a stick at. However, there might be some unrealistic expectations for the company’s immediate future from within the company. All Things D is reports:

A few months later, CEO Dick Costolo told employees he expected to get to 400 million users by the end of 2013, according to people familiar with the company. Sources say that Twitter now has around 240 million users, which means it has been adding fewer than 4.5 million users a month in 2013. If it continued to grow at that rate, it would end this year around the 260 million mark — meaning that its user base would have grown by about 30 percent, instead of Costolo’s 100 percent goal.

Frankly, it’s hard to see how Twitter would double its users that quickly when it took so long to get to the 200 million mark in the first place. It certainly doesn’t seem to be losing any popularity, but that’s a pretty big goal to live up to.

Image: Dick Costolo (Twitter)