Men who work in the steel industry and are exposed to high temperatures are prone to develop kidney or urinary stones, Brazilian researchers said on Wednesday.

Dr. Cassio Andreoni, and colleagues at the Federal University of Sao Paulo, analyzed the medical records of 10,326 men working in the steel industry.

The subjects were divided into two groups - the 1289 who worked in areas with temperatures greater than 45 degrees C, and 9037 who worked at normal temperatures.

Overall, 181 men (2 percent) had at least one episode of urinary stones, the investigators report in the medical journal Urology. Of these, 103 worked hot areas (representing 8 percent of that group) and 78 were in the room-temperature group (0.9 percent).

The investigators then looked more closely at the body chemistry of 59 workers - 34 hot-area workers and 25 normal-temperature workers.

The team found that low levels of citrate in urine occurred more often in men in the hot-area group than those in the room-temperature group (56 percent versus 28 percent). Men in the hot-area group were also twice as likely to have low urine volumes. Both these conditions are involved in stone formation.

To minimize the risk of kidney stones for people who work in a high-temperature environment, “it is important to encourage the workers to increase their ingestion of liquids during the period of heat exposure,” Andreoni’s team advises.

They also say that, to offset low citrate levels, “the use of diluted potassium citrate in the water the workers drink could be recommended; lemonade could represent another source of citrate.”

SOURCE: Urology, May 2005.