This is the 12316th most frequent Turkish word.
hastalarından
"From his/her/their patients."
In this sentence, 'hastalarından' indicates ownership and is part of a prepositional phrase, meaning 'from his/her patients'.
Doktor, hastalarından biriyle ilgileniyor.
The doctor is attending to one of his/her patients.
Here, 'hastalarından' functions as an ablative plural noun, indicating that the thanks came 'from his/her patients'.
O, hastalarından teşekkür aldı.
He/She received thanks from his/her patients.
In this case, 'hastalarından' specifies 'among his/her patients' and is used to describe a subset.