Bolsover MP Dennis Skinner is at home resting after being admitted to hospital.
The 84-year-old firebrand Labour politician has a low red blood cell count.
An ECG was also performed on former miner Mr Skinner, who underwent a double heart bypass operation in 2003, and this was found to be OK.
Mr Skinner - who has represented Bolsover since 1970 - was admitted to hospital on Friday.
Chesterfield MP Toby Perkins tweeted: "Get well soon to my neighbour, colleague and friend Dennis Skinner. Hope you're back terrorising the Tories soon."