nginx - read custom header from upstream server

I am using nginx as a reverse proxy and trying to read a custom header from the response of an upstream server (Apache) without success. The Apache response is the following: HTTP/1.0 200 OK Date: Fri, 14 Sep 2012 20:18:29 GMT Server: Apache/2.2.17 (Ubuntu) X-Powered-By: PHP/5.3.5-1ubuntu7.10 Connection: close Content-Type: application/json; charset=UTF-8 My-custom-header: 1 I want to read the value from **My-custom-header** and use it in a if clause: location / { // ... // get My-custom-header value here // ... } Is this possible?