I am looking for some help on swollen feet. Yesterday, I was on the computer for some time, and when I tried to put my shoes on to go out I discovered that they were too tight. I then looked at my feet and they were swollen. I am concerned. I feel that the computer wasn’t the problem. My feet did not reduce in size much overnight and have begun swelling more today. This has never happened before and I don’t know what to do. Can you give me some advice?
Swelling of the feet is a common symptom, and generations of medical students have had it drilled into them that they must consider serious heart, liver, or kidney disease when evaluating someone with it. In my experience though, most cases of swollen feet seen in the office stem from much more mundane causes, and are not indicative of serious disease.
When we talk about swelling of the feet or lower legs, we are talking about pitting edema, that is a swelling that pits if you press on it with a finger. This is caused by an increase in the interstitial fluid in the feet, the fluid that is neither within the cells nor within the blood vessels. To understand why it occurs, we need to know how the fluid in our bodies stays where it is supposed to be in the first place.
Fluid in our cells accounts for about 40 percent of body weight, that in our blood vessels about 5 percent, and interstitial fluid makes up an additional 15 percent. Fluid in the blood vessels and interstitial fluid always contains sodium, in about the same concentration. The fluid in the cells contains little sodium.
Sodium is regulated by our kidneys. Within a day of so of eating extra sodium, our kidneys will excrete more, and if our sodium consumption drops, our kidneys will conserve it. Since sodium passes freely between the fluid in our blood vessels and the interstitial fluid, three-quarters of the sodium we eat will wind up in the interstitial fluid, at least until the kidneys are able to excrete it, and this extra sodium is always accompanied by extra fluid.
Another factor involved in the distribution of water is the protein in our blood, which cannot pass freely into the interstitial fluid, and therefore tends to hold fluid in the vessels by osmotic pressure. Also hydrostatic pressure, the pressure produced by the weight of the column of fluid in our blood vessels, will tend to force fluid out in areas where the pressure is high, as in the feet or lower legs. Interstitial fluid is constantly being collected and returned to the blood vessels through lymphatic channels.
In heart failure, the kidneys hold onto excessive amounts of sodium, which along with the water that always accompanies it can wind up in the lowest part of the body, the feet. Severe liver disease and some kidney diseases can cause a major drop in the amount of protein in the blood. This changes the osmotic pressure, allowing more sodium and fluid to escape from the blood vessels.
But as I mentioned above, most cases of pitting edema that one sees in the office come from more mundane conditions. Activities that increase the hydrostatic pressure in the feet such as sitting in a chair or airplane seat for many hours allows fluid to build up in the interstitial space, and with inactivity there is no pumping action by the leg muscles to return the fluid up into the chest and the blood vessels.
Varicose veins will cause edema by preventing the smooth return of blood in the veins, and increasing the hydrostatic pressure in the lower legs. Being obese, wearing constrictive clothing around the upper thighs, or knotting stockings around the leg above the knee all increase that pressure, and prevent the return of blood.
Simply eating a large sodium load (a big meal of heavily salted food) can increase the sodium content of the body sufficiently to cause edema for a day of so until the kidneys can excrete it. And obviously many combinations of these factors may be present. A few varicose veins and sitting at the computer more than usual the day after a big meal of Chinese food will do it.
One of the easiest ways to deal with edema is to always keep the feet up when sitting down. Try to keep them above hip level. Try to walk or jog in place for a minute or two every 15 minutes if you have to stay sitting down. Watch the amount of salt you use on food. The average American diet is way too high in salt content anyway. Drink extra water to help flush the sodium out. Finally, if you have varicose veins, using supportive hose when you must be sitting for a prolonged period will help prevent the buildup of edema.
If these simple measures don’t work, then you should check it out with your doctor. A simple exam and some blood tests can rule out the serious causes of edema, and if the problem persists, the occasional use of a mild diuretic, which forces the kidneys to excrete more sodium, will probably take care of the problem.
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