Leishman had told a close family friend he hoped to be back at work in a few weeks, but his brother was more cautious.
"I think he's certainly got a bit of resting up to do. It's an exhausting business, as you can imagine. He'll probably find out later in the week what the best advice is."
Leishman had been buoyed by the messages of goodwill he had received, his brother said.
"It's been fantastic, and it's really lifted him up."
A broadcaster since 1970, Leishman has been a longtime fixture of New Zealand's television landscape. Most recently he has hosted Golf Club and The Golf Show.
He has also covered Olympic and Commonwealth Games for TVNZ, as well as yachting, tennis, league and rugby.