When you (or loved ones) are taking prescription or over the counter medications…there is a lot you should be worried about, and a lot that your pharmacist may not be telling you.

Most people are aware, for example, that several medications taken together can sometimes cause harmful interactions. Most also know that drug allergies can pose significant hazards. (These are topics of other articles in this series). And, many people know that young children, elderly adults, pregnant women, nursing women, and severely debilitated people may all be at higher risk for adverse drug events.

But what most people don’t know is that a simple blood test can be one of the most important pieces of information in determining the correct dose of many medications…and the results of that test are almost never available to your pharmacist, especially if your pharmacist fills your prescription in a retail drugstore. (And, that’s a bummer.)

The test I’m talking about, of course, is the ’serum creatinine test’ (’SEAR-’em cree-AT-tuh-neen tehst’. It’s a difficult name to pronounce and a difficult test to understand…but one that you NEED to know about if you or loved ones are taking over-the-counter or prescription medications.)

A serum creatinine test gives a physician or pharmacist an estimate of kidney function.

Serum creatinine is the ‘bean counter’ of modern medicine… letting folks know if the beans (the kidneys) are working as well as they should.

Why is that important?

Well, kidney function is extremely important in determining the correct doses of many medications since the kidneys (along with the liver) assist in the removal of medications from the body.

Almost all medications (and/or their chemical by-products) are either removed by the liver, by the kidneys, or, in many cases, by both the kidneys and liver working together.

So, simply put, when the beans are not working well, many medications will accumulate in the body and increase the risk of drug side effects. And that’s an even bigger bummer. (The same is true for liver problems, and we will talk about that in another article in this series.)

As a result, patients with reduced kidney function often need LOWER doses of many medications.

So how does this all work?

Well, creatinine is a chemical that occurs and circulates naturally in the human body. It is the result of normal protein break-down. And, like many medications, creatinine is normally removed from the blood by the beans. So, when the kidneys are not working well, the level of creatinine circulating in the bloodstream will start to go up…just like the blood level of many medications.

Physicians and pharmacists are routinely and easily able to determine how much creatinine is in the blood with the results of a serum creatinine test. (This test is part of a very common panel of blood tests. And, if the serum creatinine is high, many drugs need to have a lower dose.) The normal value for serum creatinine is about 0.4 to 1.5 mg/dl…but that can vary a bit from lab to lab.

So remember: ‘kidneys no work…serum creatinine go UP’.

Now, serum creatinine is not the best measure of kidney function (there are other tests that are much more accurate), but results of the serum creatinine test are usually the most readily available…and cheapest…and are generally accurate enough for most purposes…so serum creatinine is the de facto standard for estimating kidney function…most of the time.

The gold standard test that doctors use for measuring kidney function is called ‘creatinine clearance’ (cree-AT-tuh-neeeen CLEAR-uhhh-nce) However, not many patients get this particular test because it is pretty darn inconvenient…and smelly. You have to collect all of your urine for 24 hours and keep it in the fridge. Not a lot of volunteers for this test…

Creatinine clearance is the volume of blood that the kidneys clear of creatinine in a given amount of time (and it is usually reported as milliliters per minute).

So, when kidney function decreases, creatinine clearance (the amount of blood that the kidneys are successfully ‘cleaning’) also decreases.

So remember: ‘kidneys no work…creatinine clearance go DOWN’. (Note: this is easy to remember because it is the exact opposite of what you were initially thinking, and the opposite of what happens with serum creatinine. Most of medicine is like this.)

Now for the super tricky part just for those gunning for an A. There is a way to ‘guestimate’ creatinine clearance using serum creatinine…isn’t that neat. And, that’s probably the best way to determine renal function if a measured creatinine clearance is not available.

What you do is run the serum creatinine value through a fancy equation that will give you an estimated creatinine clearance, which is itself an estimate of kidney function. (Estimates of estimates of estimates…that’s the kind of exacting science I live for.)

For adults, that equation is the famous ‘Cockcroft-Gault equation corrected for ideal body weight and gender’…the equation everyone loves to hate. The Cockcroft-Gault equation (presumably named after Drs. Cockcroft and Gault…or maybe just Dr. Cockroft-Gault, or maybe Lara Croft), is generally considered very reliable since it has never been well validated in young patients, old patients, thin patients, fat patients…basically all the patients it gets used on. So go figure. Double bonus points if you can remember this:

For men, creatinine clearance =

((140- Age) ‘ IBW) / (72 ‘ SCr)

For women, creatinine clearance =

((140- Age) ‘ IBW ‘ 0.85) / (72 ‘ SCr)

Where Age is in years, IBW is ideal body weight in kilograms, and SCr is serum creatinine in mg/dl.

Now once you run this a few times, you’ll find that creatinine clearance for young healthy people is about 100 ml/min (we’ll just leave off the ‘ml/min’ part from now on).

And, dead people have a creatinine clearance of about 0, depending on how healthy they are.

Everyone else falls somewhere in between.

(Now someone in the back of the room is saying, ‘I just ran this on myself and I have a creatinine clearance of 150′. Well aren’t you special? In fact, young good-looking people can have creatinine clearances of 130, 140, or more…but it doesn’t do a whole lot of good since 100 is perfectly acceptable. In fact, it’s just another case of overachiever overkill.)

Now, if someone has a creatinine clearance of 80, that means that they have about…80% kidney function.

And, if someone has a creatinine clearance of 50, that means that they have about…50% kidney function. (Are you following all of this?)

Many drugs that are eliminated by the kidney will require moderate dosage reductions once a patient’s renal function is in the 40-60 range.

Patients in the 20-40 range will typically require very large reductions in dose.

And, patients who are in the ‘less than 20′ range will often need HUGE dosage reductions for medications eliminated by the kidney (or better yet, they’ll need to take medications that are removed by some other organ altogether…if such an alternative is available).

One last tidbit to consider. Renal function declines as people age. No getting around that. But, the rate of decline is different for different people. By the time you’re 50 years old, there is a reasonable chance you’ll have moderate renal function (or worse)…by the time you’re 80, you’ll almost certainly have some important degree of renal impairment… and you probably won’t even know it or feel it.

Now that you know more renal physiology than you ever, EVER wanted to know…let’s get back to the main thread of this article…medication safety.

If you (or a loved one) are at risk for having decreased kidney function (and I’ll tell you who such folks are in just a second), you need to step up to the plate and get a handle on this issue (because there is a very good chance that your physician and pharmacist either didn’t have renal function data or didn’t consider it when coming up with a dosage for you).

Here are the steps I recommend for everyone taking prescription or over-the-counter medications:

1) For everyone: If you have access to the results of a recent serum creatinine test (it is probably part of your annual physical and you may have gotten a copy), memorize it or write it down and then say to your physician or pharmacist when you get a medication, ‘Say, I think my serum creatinine is about X. So, does this medication need any dosage adjustment in order to be safe for me?

2) If you are in one of the following categories, you should expect your physician and pharmacist to have considered your renal function before dosing a medication:

• known kidney disease;
• age greater than 50;
• history or heart attack, angina, stroke, or other artery blockages;
• history of diabetes (any type);
• history of high blood pressure;
• prior exposure to chemotherapy drugs;
• prior prolonged exposure to IV antibiotics;
• frequent use of pain medications (especially non-steroidal anti-inflammatory drugs, but others as well).

So you might say to your physician or pharmacist, ‘Is this drug removed by the kidney, because I have condition X that could decrease kidney function and I just want to be safe.’ If the drug is removed by the kidney, you might also ask the physician or pharmacist to tell you what your serum creatinine is…and if he or she does not have this information, a big red flag should be going up in your head.

3) If you are not in one of the categories in question 2 and you don’t have a serum creatinine available, don’t worry. You’re probably safe. But you may want to ask your physician if there is a serum creatinine in your chart and if so, what it is.

4) If you are on dialysis of any sort, serum creatinine is not all that useful for dosing medications. Just make sure your physician and pharmacist are aware that you are on dialysis and perhaps ask, ‘Now is this the usual dose for someone on dialysis?’

These are some of the steps I hope you will consider the next time you get a prescription or over-the-counter medication so you can be sure that that you (or your loved one) are getting the right dose.

This must be a mistake! How could his drug costs rise from $150 a month to $1101 in just three weeks? My hands shook while I read the pharmacy bill.

There was no mistake. The bill I held recorded the drugs ordered by my fathers Alzheimers’ care unit. In only three weeks at this eldercare facility, his drug expenses had soared an incredible 734%. Ironically, his quality of life had plunged about the same percent. Walking and talking when he entered, he now spent his days confined to a wheelchair, unable to walk, drugged into a persistent stupor.

“I’ve got to do something.” The thought haunted me all day.

Then, that evening, an incidental trip to the grocery delivered the help I needed. It came in the form of a thick paperback book, The PDR Pocket Guide to Prescription Drugs (PDR Pocket Guide).

The PDR Pocket Guide provides tons of information for all prescription drugs on the market when it was printed. Specifics include:

• generic equivalents,
• why the drug is prescribed,
• how it should be taken,
• when it should not be taken,
• side effects and special warning, and
• possible interactions with other drugs and food.

The PDR Pocket Guide is available through Amazon.com, or you might find a copy like I did at your local grocery or bookstore. Jam-packed with almost 1700 pages of information, this paperback is a surprisingly affordable $6.99.

Using the pharmacy’s bill as a list of medications, I read the PDR report for each drug my father was using. What I found astonished me.

Two of fifteen drugs prescribed were being used “off-label” (not FDA approved for the condition it is used to treat). One of those was specifically contraindicated for use with Alzheimer’s patients. Two more were from drug families that I had previously identified as causing allergic reactions in my father.

When I was young, my father used to kid me by saying, “Up with this I will not put!” Up with this I wasn’t about to put either, so I called his doctor.

“My father is allergic to Furosemide.”

He bristled. “Where did you get an idea like that?”

“Furosemide is a sulfa drug. He’s allergic to sulfa drugs.”

“I never heard anything like that about Furosemide,” he barked. “Who told you that?”

“The PDR Pocket Guide.”

“Well, the PDR has a lot of stuff you don’t need to know.” His arrogance grated on my nerves.

“No more Furosemide.” Now I wasn’t asking, I was demanding. “You’ve seen his rash. He didn’t have it when he came to the care unit.”

“You’re not qualified to say what he should or should not have.”

“What am I doing,” I wondered, “arguing with a doctor who should be helping?” I wish I’d spoken the words I thought next. “Bye-bye! You’re fired!”

But, in that moment, I resolved to be fully in control of all my father’s drugs. I would learn everything I could and provide drugs direct to the facility. . .or not. There would be no more ordering drugs without my specific authorization

I enlisted the expertise of a pharmacist I found just down the street. She graciously took time from her crowded day to answer all my questions and explain anything I didn’t understand. She took a brief history of my father’s illness, made note of his allergies, and offered money-saving suggestions. She focused on providing excellent service. In short, she was, and is, an angel.

I immediately began to look for another physician to take over my father’s care, but I was too slow. Within a few weeks, my father died of complications from a massive insulin overdose.

Was my experience unusual? Probably not, according to a study from the Medical Expenditure Panel Survey (MEPS). On the subject of the increased cost of pharmaceuticals for people over-65, the study’s author, Marie Stagnitti, MPA, reports:

Every year from 1997-2000, the average out of pocket expense for prescription medicines for those with a purchase and age 65 and older was more than three times as high as the average out of pocket expense on prescription medicines for those with a purchase and under age 65.

The potential for overmedication in the elderly is clear in Stagnitti’s chart showing an average 23.5 prescriptions in both 1999 and 2000 for the over-65 group that used prescription drugs. The number of prescription drugs used by the under-65 group seemed high to me as well: 9.5 for 1999 and 10.1 prescriptions for the year 2000.

Overmedication is not only crushingly expensive for our elderly, it represents a real and present danger. You can do something about it. Please, learn about and oversee medications. You will help elders save money. You might even save a life.

Prescription drugs can save your life. But interactions between prescription drugs and other drugs or with illnesses or conditions you have can lead to significant consequences. Drug interactions may make your drug less effective, cause unexpected side effects, or increase the action of a particular drug.

Keep in mind that this table does not show you:

-all the interactions with the drug in the left column

-other things that might interact with drugs in the middle column

-all the effects of the interaction between the two drugs (as shown in the right column)

How Can I prevent these interactions?

Here are several suggestions for limiting the possibility of experiencing these effects:

* Make sure that all of your doctors know all of the medications you’re taking, including over-the-counter drugs. Elderly persons in particular may see several different specialists. All your doctors should know about anything you’re taking

* Make sure you know all the medications you’re taking. If you’re on several, you should keep their names and doses jotted down on an index card in your wallet or purse. That way, you can reference them if you happen to end up in the emergency room or if you begin working with a new healthcare provider.

* Read the labels. Before using any product, including an over-the-counter medication, read the label for interactions. If you don’t know whether one of the medications you’re taking fits a category of drugs you shouldn’t use, ask the pharmacist for assistance.

* Make friends with your pharmacist. If you always go to the same pharmacy, your pharmacist will have all your drugs on record and can alert you to potential interactions. If possible, finding a pharmacy where there are only one or two pharmacists who are always on duty will improve the chances of them catching problems.

* Even topical medications can interact. You may be receiving an antibiotic ointment for a skin condition - ask your healthcare provider about whether you need to wear sunscreen (to prevent the sun interacting with the medication and giving you a burn!) while using it.

* Other things to think about:

1. Herbal supplements, even if purchased in the store, may not have a complete list of interactions available. Speak with your physician about whether these herbal supplements might harm you - if you’re not sure, it’s not worth the risk.

2. If you enjoy alcoholic beverages, ask your pharmacist about possible interactions with your medications; you may need to give them a miss until you are through with your medication

3. Even things that don’t seem like “real” medicine (antacids, vitamins, diet pills, fiber supplements) may make it difficult for you to absorb your medications or interfere with their function; your pharmacist can be a good resource in determining what to take.

I recently had a reader send me this comment:

“As a full-time dad I have to deal with just about every minor illness my two children pickup, everything from a bump on the head to chicken pox. I found the Highway to Health ebook very useful and it’s one of the first things I reach for when something goes wrong!”

Mr John Bradbury
United Kingdom

It got me thinking - although the Highway to Health does cover headaches, perhaps going into a little more detail about ‘bumps on the head’ would be useful. So here we go…

There are two main types of head injury - concussion and compression.

*Concussion* is the commonest:

All medications, which include prescriptions, over-the-counter preparations, vitamin and mineral supplements, and herbal preparations, are potentially dangerous. Following some simple rules will not only reduce your chance of having a problem, but should reduce your cost as well.