Monday, November 17, 2008

The excesses of modern life and kidney stones

The article “A Rise in Kidney Stones Is Seen in U.S. Children” was recently featured in the New York Times.

The article reported what is a perceived increase in kidney stones in children and attempted to explain the phenomenon based on changes in lifestyle. The idea is that, as the genetics of the population have not changed significantly, increases in kidney stones can be attributed to changes in the environment.

Generalizing from what is known about kidney stones in adults, I will briefly expand on the points made in the article so that the reader has a fuller view of how our lifestyle today (a life of excess, if I may) contributes to kidney stones.

Below is a brief list outlining the topics to be discussed over a series of entries:

  1. (Water)

  2. Salt

  3. Protein

  4. Weight

  5. Colas

  6. Exercise

Be aware: while for many people kidney stones are preventable, there are, however, underlying metabolic and medical causes of kidney stones, and kidney stones are a reason for evaluation by your physician.

Kidney stones are the aggregation of crystals in the urine

One way to conceptualize how kidney stones are formed is to think back to the experiment you did in grade school in which while stirring water you slowly added more and more salt. Initially, the additional salt fully dissolved in the water, but a point arose when the water could no longer hold any more salt, when the sodium suddenly precipitated out and crystals developed. While this is an overly simplistic analogy for how kidney stones form (the urine, for instance, contains molecules such as citrate that attempt to prevent the formation of crystals or kidney stones), it can be a useful one.

1. Water

The analogy clearly is useful in understanding how a lack of sufficient water intake predisposes people to the formation of kidney stones and how drinking more water is the best way to prevent kidney stones. The more water we drink, the more we dilute our urine and the greater difficulty crystals have in aggregating.

How much fluid to drink?

The more important question, of course, is how much should people urinate or how dilute should the urine be. The recommendation is that people with kidney stones should pass a little over 2 liters (~1/2 gallon) of urine per day, which amounts to drinking ~ 3 liters of fluid per day. Also, because a concentrated urine at any time of the day still predisposes to kidney stones, the fluid intake should be spaced throughout the day, including at night. Those living in hotter climates or engaged in heavy exercise likely need to drink more, as they are losing much of the water in ways other than through the kidneys, such as through the skin by sweating.

A rule of thumb: if the urine of a person with kidney stones looks like water (clear, not yellow) throughout the day than that person is drinking enough water.

Caution: there are dangers to drinking too much water (please consult with your doctor), and those of us not predisposed to kidney stones do not need to meet those amounts.

(the discussion of other lifestyle elements contributing to kidney stones to be continued in future entries...)

Tuesday, November 11, 2008

Nasal spray decongestants, underrecognized limitations

Mr. Jones came into the office complaining of ongoing nasal congestion since his most recent cold. "Doc, it's been weeks, and I can't get my nose to clear up. The only relief I get is from this nasal spray, and it doesn't seem to do much anymore." He pulled the bottle of nasal spray from his pocket to show me. "But if I don't use it, I can't breathe."

In the throes of an illness, we reach for any and all potential remedies for a little relief, including the nasal spray decongestants conveniently found over the counter at our local pharmacy. Nasal spray decongestants, such as Afrin, work by constricting the blood vessels in the inflamed lining or mucosa of our nose and in so doing attempt to shrink the mucosa, open the passages and help us breathe.

In studies, however, the benefit after a single dose compared to placebo (the placebo always has some benefit, often significant) is only about a ten to fifteen percent improvement in reported symptoms, and this benefit quickly wanes with each subsequent dose. The nasal congestion returns, and after continued use of the spray for a few days, there is no benefit.

Of course, most illnesses last longer than three days, and therefore people find themselves continuing to use the spray. (To compensate and find some relief, people often then increase the frequency of sprays.) Unfortunately, after using the nasal spray for more than a few days, people suddenly discover on trying to stop that they can't.

Rebound Congestion

The mucosa in their nose is even more inflamed and their congestion is even more severe than if they had never used the spray. They have what is called rebound congestion.

People using nasal spray decongestants for prolonged periods of time essentially become addicted to the spray and not because of any 'high," but a stuffed nose from which a person struggles to breathe is truly frustrating.

Do not use this product for more than 3 days.

Many people believe that the warning labels on over the counter medications are meant to be taken with a grain of salt, if not ignored altogether, but that is short-sighted. The warning on the nasal spray decongestant labels can't be written in large enough letters. The sprays are simple over the counter (OTC) medications, but one of the greatest difficulties ENT (ear, nose & throat) doctors face in their practice is getting people off of them.

Names of nasal spray decongestants

The list below is a non-exhaustive list of over the counter nasal spray decongestants in this class and their active ingredients.

Active ingredients:

oxymetazoline - Afrin, Vicks Sinex
phenylephrine - Dristan, Neo Synephrine

What this class of sprays have in common is that they are adrenergic (like adrenaline - what is released into the blood on seeing a bear). While they are topical nasal sprays, there is always a degree of absorption, even if small, across the mucosa of the nose. As a result those with high blood pressure or otherwise predisposed to heart attacks or strokes are also instructed by the label not to use these nasal sprays.

Alternative OTC nasal sprays

Often forgotten saline (salt water) nasal sprays can be quite effective in relieving symptoms of nasal congestion and potentially decreasing the risk of sinus infections, as they moisten the mucus and allow the sinuses to keep draining. (A draining sinus is generally not an infected sinus.) A runny nose is merely a nuisance.

The truth about cold medicines

Despite the commercials for nasal spray decongestants and other cold medications and despite the fact that we live in a world of the internet, high definition TVs and portable telephones, there really is no great over the counter medication for a cold. None are tremendously better than placebo and none are without the potential for side effects. There is something to be said for being on some level accepting of a cold and the stuffy or runny nose that comes with it. If only we always have the luxury to be that patient.

More about cold medicines in a future entry..

Tuesday, November 4, 2008

Strep, antibiotics, and acute rheumatic fever

“My throat is killing me” was the first thing Mr. Jones said on seeing me in the office on Monday. He had developed a sore throat on Friday of the past week, and after suffering through the weekend and not improving, he broke down and made an appointment. While he wasn't sure what I could offer him – he didn't think he had strep throat1 - he was miserable and subconsciously hoped I might give him an antibiotic anyway and he would get better sooner. He wanted relief. Swallowing was still exceptionally painful and, while he admitted loving ice cream, he was clearly tired of eating only ice cream.

I could sense his frustration, but before falsely raising his expectations for antibiotics and disappointing him further I felt compelled to tell him that, while I would do the best I could to help him feel better, antibiotics at that point would unlikely shorten the course even if he had strep throat.

“Thanks Doc,” Mr. Jones joked, feigning for the door before sitting back down.

I explained that strep throat generally resolves on its own within five days (more than a week is unusual), and in the few studies suggesting that antibiotics can shorten the course (only by a day or two), antibiotics were started within the first forty-eight hours of symptoms.

I reassured Mr. Jones, though, that all hope was not lost and that there are in fact potential benefits to being diagnosed late with strep throat and delaying the start of antibiotics. Studies suggest that starting antibiotics late, at least two days after the onset of symptoms, is actually associated with a much lower risk of its recurrence during the same strep season.

“So I'm better off not having started antibiotics?” Mr. Jones asked.

While guidelines do not recommend delaying antibiotics in strep throat, the theory behind doing so is to provide the body the time to better develop antibodies to the bacteria, a stronger immune reaction, and memory for protection the next time the person is exposed.

“Why bother then to take antibiotics at all?”

As discussed, antibiotics started early have the ability to shorten the course of strep throat. Antibiotics also decrease the transmission of strep throat to close contacts, including family members. Studies performed with penicillin (still considered the first line treatment for strep throat), show that patients are minimally contagious within twenty-four hours of starting antibiotics.

“Sure, but...”

The main reason for administering antibiotics in strep throat, however, is to prevent acute rheumatic fever. Acute rheumatic fever is an inflammatory, autoimmune (the body attacking itself) reaction that can develop in untreated strep throat. “…the immune system [normally] works by recognizing constant and variable patterns on ‘foreign’ materials and microbes that don’t originate in the host and targeting these invaders and the cells that harbor them for destruction and elimination.” (from A.B.’s entry “Biology of a Cure for HIV,”) In acute rheumatic fever the immune system confuses the patterns on the bacteria with those on tissues in the body, including the heart. Long term damage to the heart and heart valves are potential, severe complications of acute rheumatic fever. (The fear with a vaccine against strep throat, that the body will attack itself, is a large reason why such a vaccine is not yet available.)

Acute rheumatic fever is thankfully rare in the United States although it is more common worldwide. It primarily affects children between 5 and 15 years of age, but can infrequently strike adults, particularly those previously affected. Some people, due to the genetics of their immune systems, are more predisposed to rheumatic fever in the setting of certain ‘rheumatogenic’ strains of strep bacteria. (The reason for the age discrimination, therefore, may be that most adults predisposed to acute rheumatic fever have already revealed themselves as such as children.)

“Sounds scary, but you just said acute rheumatic fever is rare in the U.S., especially for an adult, and that strep throat will go away in a few days anyway. Again, I'm confused, why should I bother with antibiotics?”

Given the severity of potential complications of acute rheumatic fever, the benefits of antibiotics are thought to outweigh the risks. Amazingly, starting the antibiotics even up to nine days after the onset of symptoms (and by then the sore throat has likely already resolved) still prevents acute rheumatic fever. A study conducted on military recruits discovered the phenomenon.

There is the potential for other rare complications of strep throat in adults, such as an extension of the infection, scarlet fever and streptococcal toxic shock syndrome.

“Yes, but don't forget I'm not so sure I have strep,” Mr Jones added.

After discussing further with Mr. Jones his symptoms, examining him and ruling out potential complications, I had to agree that I didn't think he had strep throat. Not unexpectedly most sore throats are viral, and strep throat makes up maybe less than 10% (one in ten) of sore throats that present to doctors. Do we give antibiotics to everyone? (for further reading on the forces at play in administering antibiotics, "Antibiotics and the common cold")

Mr. Jones, however, had enough symptoms that I couldn't be sure that he didn't have strep throat, and I recommended we evaluate further. Even the most experienced doctors are notoriously unable to reliably diagnose who has strep throat by only history and exam.

How then do doctors evaluate sore throats and determine who has strep and who needs antibiotics? A blog entry for another day, but Mr. Jones ended up on throat culture having strep throat.


1Strep throat (streptococcal pharyngitis): an infection of the throat by a particular type of bacteria, Group A streptococcus.