Urine Reagent Strips for Assessing Hypohydration — Do They Work?

Hydrated or not?

Hydration status is an important issue in sports medicine.  Both ends of the spectrum — hypo and hyperhydration — increase risk for morbidity and mortality in the athlete.  As we all know, maintaining euvolemia is an important step in the prevention of heat illness, as the evaporative effect of sweating is one of the body’s mechanisms for heat dissipation.  Conversely, as my colleague and CJSM author Dr. Tamara Hew-Butler has argued on different platforms, a zeal to overhydrate can lead to hyperhydration, hyponatremia, and in extreme cases, death.

There is another way we concern ourselves with hydration status in sports medicine, and that is when assessing athletes who compete in weight classes, or when doing urine drug testing as a screen at a doping control station in competition.  Typically, such assessments are done using different testing modalities on urine specimens.

I am a Medical Delegate for the Federation Internationale de Natation (FINA) and am involved in doping control at long-distance swimming events.  Urine drug screens cannot reliably be done on dilute urine specimens.  In most settings we use refractometry but in some more remote or less developed venues, we may need to use urine reagent strips [WADA has different standards of specific gravity (SG) suitable for urine testing depending on whether refractometry or urine reagent strips are used].

More commonly, here in central Ohio, is the need to assess for hypohydration in the popular sport of wrestling [wrestlers — and other athletes competing in weight classes — will frequently sweat and minimize fluid intake prior to a competitive weigh-in to ‘make weight’ in the class in which they want to compete].  In Ohio high school wrestling, urine reagent strips only are used, and the standard is any sample with SG >1.025 results in a disqualification, with a minimum time period of 48 hours before reassessment.

Having an interest in all these dimensions of testing an athlete’s hydration status, I read with great interest the Brief Report that was published in the November 2019 CJSM: Urine Reagent Strips Are Inaccurate for Assessing Hypohydration: A Brief Report. Read more of this post