Rainer was born in Graz, Austria-Hungary. In 1918, at age 18, he was measured at 122.55 cm (4 ft 0.25 in). A typical defining characteristic of dwarfism is an adult height below 147 cm (4 ft 10 in). Then, likely as a result of a pituitary tumor, he had a dramatic growth spurt so that by 1932 at the age of 32 he had reached a height of 218 cm (7 ft 2 in). As a result of his gigantism he became bedridden for the rest of his life. When he died in 1950 (age 51) he had reached a height of 234 cm (7 ft 8 in). His feet measured 33.3 cm (13.1 inches). His hands measured 24.8 cm (9.8 inches).
- Guinness World Records, 2004.
- Bellows, Alan. "The Man Who Was a Dwarf and a Giant", DamnInteresting.com, 1 December 2005.
- Hirsch, Obar. Two Types of Gigantism Due to Similar Tumors. Discussion of Growth* Confinia Neurologica, Vol. 21, No. 4 (1961)
- Adam Rainer at The Tallest Man