Amazonian Daynara de Paula, 20, one of Brazil's breakout women swimmers of the past year, has tested positive for the diuretic Furosemide. The test dates from the South American Games in Medellin, Colombia, last month, the positive finding reported by the Brazilian Olympic committee and the Brazilian swim federation (CBDA). 

The swimmer has opted to step aside from racing at the Troféu Maria Lenk next week. If, as is likely, the finding results in a two-year suspension in accordance with the rules of FINA and the WADA Code it signs up to, de Paula will also forfeit all results of the six months prior to anti-doping test. De Paula, who finished 8th in the final of the 50m butterfly at Rome2009 world titles last summer, won five gold medals in Medellin: 50m and 100m butterfly, and three relays. 

The explanation of Sandra Soldan, ex-triathlete and representing the Brazil federation as medical officer, leaves much to be desired. She tells Brazilian papers today that the swimmer mentioned tablets that she bought at a chemist, adding: "She [de Paula] went before the COB [Brazilian Olympic Committee] yesterday to provide explantion. The positive for Furosemide is strange because there is no benefit to be had from it."

As anyone in sport and sports medicine knows very well, diuretics, which cause the downfall of a fair number of Chinese swimmers at the world championships in 1998, are used to flush the system of more damning evidence and that is why they are listed on the prohibited substances chart. Diuretics are used by some as a means of fast weight reduction (sports with weight divisions come to mind), by others as a way of cleaning the system of evidence that anabolic agents and other banned substances have been used.

To be fair to Soldan, her comment is made in this context: De Paula is 1.75 tall and weighs 52kg. Hardly the most likely candidate for a diuretic. Her full explanation will doubtless be sought when the case comes to fruition.

FINA is due to determine the level of penalty in the next few days, the CBDA noted yesterday. A suspension of up to two years is almost inevitable.

Here is a measure de Paula's progress of late:

• 50m butterfly: 2009: 25.85; 2008; 26.57; 2007: 27.93
• 100m butterfly: 2009: 57.68; 2008: 59.20; 1:01.83

Big jumps, but of their time nothing all that extraordinary: they coincided with the arrival of suits that boosted performance. The suits are now banned, and in Medellin, De Paula won her butterfly crowns in 26.77 and 1:00.44, down on her 2008 best and well down on her 2009 best.