Just Pissing It Away

It's been quiet in my corner of the blogosphere, but I lay the blame squarely on the fact that my latest round of exams has kept me extremely busy. Ths plus side of all this is that I get to come back to lots of news, all ripe for comment!

Like this article published today analyzing a couple studies from early 2000 about certain drugs prescribed for high blood pressure being potentially tied to bone loss, particularly in older men.

Most of the time, our sound bite-focused media doesn't get the whole story out there. This article is no exception.

Diuretics are commonly called "water pills," particularly by older people. I really, really hate that term. It isn't even remotely appropriate for describing how diuretics function. I suppose that the analogy comes from the idea that drinking more water causes increased urination, and taking diuretics causes increased urination; hence, diuretics are "water in pill form," except that that totally fails to explain how they work to lower blood pressure. Normally I don't think it's necessary for patients to know the mechanisms of action for the drugs they take--such details are excessively complicated. But we strive to explain things in the simplest way we can without sacrificing accuracy. Antidepressants, for example, are said to "balance or correct problems in brain chemistry." This is simple, but true at the base level.

Diuretics don't add anything to your body, and they certainly don't hydrate you. They have varying mechanisms of action, but what they really do is increase the body's excretion of certain elements that float around in the body in ion form. Sodium, potassium, and calcium are three good examples--they are commonly called "electrolytes," especially if you like reading the labels on your sports drinks. Generally, sodium loss is desirable in patients with high blood pressure. All of these ions must be present in proper concentrations for the body's various functions to work properly. Too much and too little are both bad. Diuretics are a convenient way to get rid of excess electrolytes.

The diuretic the article is talking about is furosemide, though there are other diuretics in the same family that have the same effect. Furosemide flushes out sodium, potassium, and calcium by preventing the kidneys from re-absorbing it at a specific point (the loop of Henle, if you're curious). Many patients on furosemide are also prescribed potassium supplements to counter the potassium loss. The calcium loss is not as frequently addressed, but it really should be; then again, most people don't get enough calcium anyway.

But saying diuretics in general are responsible for worsening bone loss is not only alarmist, it's false. Hydrochlorothiazide, or HCTZ, actually results in calcium retention. Sometimes this is a problem, as it can cause calcium levels in the blood to get too high. But for some patients with high blood pressure who are also at risk for osteoporosis, HCTZ is a great drug; it helps them retain extra calcium, improving bone density! This doesn't mean that everyone at risk for osteoporosis should be on HCTZ; increasing dietary calcium and vitamin D are a much better idea. But when treating patients with high blood pressure, it is often best to use drugs that "kill two birds with one stone." Likewise, it doesn't mean that patients at risk for bone loss shouldn't get furosemide. This is what trained physicians and pharmacists are for--evaluating the complicated mess of risks, benefits, and drug interactions that make modern medical therapy so difficult to manage.

And that's the bottom line--medicine is complicated. One 200-word article in a newspaper is never going to explain all the ins and outs of any particular treatment or drug; that's why scholarly journal articles are long, detailed, and extensively referenced. So consider very carefully where you get your information; chances are that if it was packaged for the general public and sold at the newsstand, you're not getting the whole story.