NEW YORK (Reuters Health) - Men who work in the steel industry and are exposed to high temperatures have an increased risk of developing urinary lithiasis, according to study findings reported by researchers in Brazil.

Dr. Cassio Andreoni, and colleagues from the Federal University of Sao Paulo, retrospectively examined the incidence of urinary lithiasis and metabolic changes in 10,326 men working in the steel industry who were exposed to high temperatures.

In the first stage, the subjects were divided into two groups - those who worked in areas with temperatures greater than 45 degrees C (n = 1289) and those who worked at normal room temperatures (n = 9037).

In the second stage, a metabolic evaluation was performed on 59 workers without urolithiasis. These subjects were divided into two groups: hot-area workers (n = 34) and room temperature workers (n = 25).

The investigators evaluated calcium, creatinine, and uric acid in serum. They also assessed the volume, calcium, uric acid, citrate, and oxalate in 24-hour urine samples.

Of the 10,326 workers, 181 (1.75%) had at least one episode of urinary stones, the investigators report in the May issue of Urology. Of these, 103 (8.0%) were in the hot-area group and 78 (0.9%) were in the room-temperature group (p < 0.001).

The metabolic evaluation demonstrated that men in the hot-area group presented more frequently with hypocitraturia than those in the room-temperature group (55.8% versus 28.0%, respectively p = 0.03). Men in the hot-area group also presented more frequently with low urinary volume (79.4% versus 48.0%, respectively; p = 0.01).

"To minimize the risk of urinary lithiasis among 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," Dr. Andreoni's team explains. "With regard to hypocitraturia, the use of diluted potassium citrate in the water the workers drink could be recommended; lemonade could represent another source of citrate."

Urology 2005:65:858-861

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