Dr Isaac Warwanamiza said he had seen 82 dead since Sunday, including 23 government soldiers, the highest death toll reported since hostilities broke out last week in the Democratic Republic of Congo.
Medical services were struggling to cope with the scale of the casualties among government troops and the M23 fighters who launched their rebellion last year, Dr Warwanamiza said.
Three UN peacekeepers were wounded on Saturday in the fighting, and a UN official said two M23 colonels had been killed.
The frontline is only nine miles north of Goma. M23 rebels briefly overtook the city late last year, and Congolese and UN troops have been fighting to dislodge rebels from heights overlooking the city since Wednesday.
Observers estimate Congolese forces have advanced less than a mile and have yet to achieve their immediate objective - cutting off M23 from a border crossing where the rebel group is believed to get supplies from Rwanda.
An army chaplain at the military hospital in Goma confirmed Congolese troops had suffered heavy casualties.
Lea Masika said another 59 wounded had been brought into the hospital, bringing the total of wounded there to 720.