E. Inventories

Our major classes of inventories were as follows as of March 31, 2013 and December 31, 2012 (in thousands):

	March 31, 2013		December 31, 2012
Raw materials	$	2,882	$	2,652
Work in process	2,022		2,524
Finished goods	6,388		7,275
Total inventories	$	11,292	$	12,451

On a quarterly basis, we analyze our inventory levels to determine whether we have any obsolete, expired, or excess inventory. If any inventory is expected to expire prior to being sold, has a cost basis in excess of its net realizable value, is in excess of expected sales requirements as determined by internal sales forecasts, or fails to meet commercial sale specifications, the inventory is written-down through a charge to cost of goods sold. The determination of whether inventory costs will be realizable requires estimates by management. A critical input in this determination is future expected inventory requirements, based on internal sales forecasts and forecasts received from Takeda. Once packaged, Feraheme/Rienso currently has a shelf-life of five years in the U.S. and between two and three years outside of the U.S., and as a result of comparison to internal sales forecasts, we expect to fully realize the carrying value of our current Feraheme/Rienso inventory. If actual market conditions are less favorable than those projected by management, additional inventory write-downs may be required. Charges for inventory write-downs are not reversed if it is later determined that the product is saleable.