Water Loading Before Appointments
In my previous blog I discussed falsifying weight by wearing weights. This time I would like to discuss a much more common circumstance in which a patient falsifies their weight by trying to drink a lot of water before they are weighed. Often this is done because they know their weight is down (since they have been secretly restricting or exercising), or they are afraid their weight is down and are anxious that the doctor or parents not find out.
Although it seemed unlikely that a person could drink enough to make a great deal of difference to a single weight, we have had a patient urinate off ten pounds of fluid (!) as she went from our office to the hospital, where she was being admitted for medical instability.
Once again, as with wearing weights, trying to "water load," as it is called, is an act of desperation. Even so, we cannot allow it and need to be aware of the mechanics of it.
What can a parent do? Water loading is not about your child being "dishonest" or "deceitful". Don't accuse them or argue about it, just do not let them drink a water bottle on the way to the doctor's office before they are weighed. Do not let them go to the bathroom in the doctor's office right before they are seen. A great deal of water gets drunk in the hall bathroom, either in the stall from a bottle carried in a purse or back pack, or from putting the mouth under the faucet (as in the patient above). And please, no stops at Starbucks before going to the doctor's!
What can a doctor do? All patients should be weighed in a gown, after a void and the specific gravity of their urine should be measured (by the way, for you Maudsley parents out there, you can buy little testing strips and test the urine yourself). If the number is 1.000 to about 1.005, water loading is almost certainly present. If it is "borderline" 1.010 or even 1.015 and it has been running a more concentrated 1.020 or 1.025, ask the child to wait 20 minutes and give another sample. Re-weigh them. If the urine stays at 1.000 or 1.005 even after this, do not give them access to water until they have released the fluid and you have checked their weight again each time.
Why do this? Why does it matter? It matters because you need to have an accurate idea of what is really going on with a child you are trying to keep stable. I recently saw a patient who served as a good example. He reported that "everything went great this week", even though I knew his parents (at my request) had begun supervising all of his meals and that, before this, he had been hiding food. His weight seemed the same (stable). His urine specific gravity was a borderline 1.015, but his previous ones had been 1.020 and 1.025. So I waited thirty minutes, had him give me another sample and re-weighed him. His weight was down nearly two pounds. When confronted he revealed that he had been throwing away his school lunches and increasing his exercise. In a panic he water-loaded to try and keep "from getting in trouble" with his team. These are things that can be difficult to find out about, but which are essential to know.
Additionally, children who drink very large quantities of water can actually dilute the sodium in their blood so rapidly they have what we call "hyponatremic seizures." Seizures, I think we all can agree, are not where we want to go.