Archive for the 'Kidney Function' category

From a Tiny Seed of Truth

Sep 12 2016 Published by under Acid-Base Disorders, Kidney Function

A colleague helpfully pointed me to a website that could put me out of business. The headline promised to repair your kidneys naturally with one ingredient.

I had to know more! Here's the magical advice:

Repairing the kidneys after damage just may lie in a common household item, which you probably already have in your kitchen cabinet. Yes, we are talking about baking soda. In this articled we are going to show you how to cleanse and improve the function of your kidneys with just ½ tsp. of baking soda,every day.

The site goes on to try and explain the magic of sodium bicarbonate, implicating a variety of body systems.

So what's the tiny seed of truth? Acid may be bad for our kidneys.

Being alive generates acid. Metabolizing the food we eat produces acid. Our kidneys produce bicarbonate to neutralize this acid, as well as excreting it in the urine. There is some evidence that higher loads of acid may promote kidney problems, including chronic kidney disease and stones. Eating a lower acid load, by minimizing meat and maximizing fresh fruits and vegetables, may slow the progression of kidney problems.

So could ingesting baking soda help? Yes, but probably not at the level recommended.

1 teaspoon of baking soda can neutralize ~72 mEq of acid. Net acid production for children is 1-2 mEq/kg body weight/day. So a lean, 70 kg adult likely produces at least 70 mEq daily. This dose of baking soda would neutralize about half of that.

The real payoff here is the advice at the bottom of the article, recommending less meat and more fruits and vegetables. A healthy diet seems to be good for everything!

Besides, baking soda is pretty nasty.

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K Lowering Drugs

Jun 30 2016 Published by under Kidney Function

As kidney function deteriorates, patients often suffer elevated levels of potassium (K) that can lead to cardiac rhythm disturbances and other bad things. For years we have prescribed sodium polystyrene sulfonate (Kayexalate), a resin that exchanges sodium (Na) for K in the gut. While it's good to then poop out the K, the patient can absorb more Na, a problem for those with kidney disease. Also, this drug is so old (how old is it?) that it was not subjected to the current level of FDA safety and efficacy studies.

Our pharmaceutical companies have provided an alternative. Patiromer (Veltassa) is a polymer that binds K without releasing Na. So far, so good. It does reduce K levels in patients. Unfortunately, it cannot be taken with other medications because it  can bind them and prevent their absorption into the body. Kidney disease patients generally require a whole bunch of drugs, so this is a bit of an issue.

I have a patient who requires some Kayexalate every day to keep blood levels normal, and it works well. However, the texture is gritty. I want to know if patiromer also has a gritty texture. I know it is more expensive, but if it annoys patients less it could be worth the money.

Have you taken patiromir or prescribed it? Let me know what you or your patients think in the comments please!

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Could Yogurt Be the Answer?

Feb 25 2016 Published by under General Health, Kidney Function

You can't swing a dead cat without hitting an article about the microbiome on the internet. Changes in the zillions of bacteria that reside in our bowels now get the blame and the glory for a variety of conditions. Collecting poo and analyzing the actual contents over time to look at contribution to disease development would take years and be cumbersome. Interested investigators therefore think of proxies that may influence microbiota that can be studied with less fuss.

YogurtA group from Buffalo, New York, decided to examine the intake of beneficial bacteria and markers of kidney dysfunction. Some people take capsules of these good bacteria, known as probiotics, while others get these critters from yogurt that still contains the active cultures responsible for its conversion from milk. They used the data from the US National Health and Nutrition Survey (NHANES) to compare yogurt and probiotic use with markers of kidney disease, including microalbuminuria and level of estimated glomerular filtration rate (eGFR). Yogurt consumption was self-reported by participants as frequent (eaten 3 or more times weekly) or infrequent (less than 3 times weekly). Probiotic use was extracted from the study surveys.

From 1999-2012, NHANES included 41,243 adult subjects with complete covariate data available for 32,749 in the cohort with probiotic data (1999-2012). Data on yogurt consumption was limited to 6853 subjects (2003-2006). Yogurt and probiotic use was associated with higher socioeconomic level, more females, and fewer African Americans. Yogurt and probiotic consumers also had fewer comorbid conditions. These differences were adjusted prior to multivariate analysis, since all of the conditions associated with frequent yogurt and probiotic intake reduce the risk of kidney problems. Frequent yogurt and probiotic users showed lower risk of either reduced eGFR or microalbuminuria (OR = 0.76; 95% CI = 0.61 - 0.94). When these markers of kidney problems were examined separately, yogurt and probiotic consumers still had lower risk of albuminuria (OR 0.74; 95% CI = 0.57 - 0.95), while no significant change in the risk of low eGFR could be demonstrated.

This study has a boatload of limitations, including relatively small sample size and its cross-sectional nature. While they adjusted their analysis for confounding variables known to change kidney disease risk, it is still likely that yogurt and probiotic consumption is a marker of "healthier people" at lower risk. While they speculate about effects of probiotics and yogurt on the microbiome, they have no evidence of this effect in their population.

For most folks, eating a few yogurts will cause no harm. It might be beneficial. But this study provides no firm foundation for a recommendation.

Nutrition Journal (2016) 15:10   *   DOI 10.1186/s12937-016-0127-3

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Urine Science as Promised: Microalbuminuria in Toddlers

Jan 08 2016 Published by under Journal Club, Kidney Function

So-called microalbuminuria first gained attention as a predictor or marker of diabetic kidney disease. We now know that it is not as good as we thought for that condition, but it is associated with renal and cardiovascular disease risk in adults. Is shedding extra albumin in the urine a risk marker or, perhaps, does it contribute to the development of these conditions? After all, these are major causes of morbidity and mortality.

Could it be that microalbuminuria precedes any of the other stuff? Are we born this way?

The first question to answer is the prevalence of microalbuminuria in children. A group in The Netherlands organized a cohort study over the first two years of life in its general population, the Groningen Expert Center for Kids with Obesity (GECKO). All children born in Drenthe, a northern Dutch province, were eligible for enrollment From April 2006 through April 2007. The primary goal of this study was to identify factors associated with overweight. Data included pregnancy complications, birth weight, placenta weight, and longitudinal anthropomorphic measurements through 5 years of age. Lifestyle and environment factors were assessed by questionnaires beginning in the last trimester of pregnancy. Over the 2-year enrollment period 4778 eligible births were recorded. For this study, a urinary albumin measurement had to be performed; 1352 children did this and were included in their analysis. Children with urine studies did not differ from the overall population for any variable studied.

Their method of urine collection sparks some controversy. Two-year-olds usually do not pee in a cup on command. Sticking a plastic baggy on the perineum requires some skill so that it hangs on long enough for the collection but does not get contaminated by stool. The investigators gave the parents a cotton wool pad to place in the diaper and mail back into the center within 24 hrs. They compared this method to voided urines and found acceptable performance for their method with bias -14 mg/dL albumin, precision 31.3 mg/L, and accuracy 48.1%. Contact with cotton is known to decrease albumin levels within 15 minutes by an average of 40% with high variability.  A nice review of issues with pediatric urine collection can be found at another link.

The standard clinical measurement of microalbuminuria is the albumin:creatinine ratio to correct for the amount of hydration. The median ratio in this study was 14.0 mg/g creatinine. The 75th percentile was 25.6 and the 95th percentile 89.3 mg/g, respectively. Based on the current criteria for microalbuminuria (ratio > 30 mg/g), 23.4% of their kids had microalbuminuria. However, this normal range comes from adult data. Toddlers often have lower creatinine levels because of their lower muscle mass. More study will be needed to determine a level of risk in this population.


Fig 3. doi: 10.1093/ndt/gfv407

The authors had data from another regional adult study (PREVEND) for comparisons, although it used concentration of albumin rather than the ratio. Using albumin concentrations, 6.9% of toddlers met criteria for microalbuminuria, similar to levels seen in healthy adults overall (Fig 3, right). This is especially true for young adults (Fig 4, below).

Fig 4. doi:  10.1093/ndt/gfv407

Fig 4. doi: 10.1093/ndt/gfv407

Effects of prenatal and early life factors to promote disease later in life have been proposed for years, most famously by Barker in the relationship between low birth weight and later cardiovascular risk.  No association could be demonstrated with birthweight, gestation age, impaired placental growth, gestational hypertension, or smoking during pregnancy, providing no support for the Barker hypothesis.

Other issues include the use of a single specimen for determination of albuminuria. A variety of factors can cause transient urinary abnormalities. Repeated elevations over weeks to months are required for clinical use at this time.

While not definitive, this study provides valuable information on microalbuminuria in toddlers. Might we be born with differences in endothelial function, or in other kidney structures, that make our kidneys leaky and predispose us to later cardiovascular disease? Only time, and further study, will tell.

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How To Fix Youth Hydration

Jun 12 2015 Published by under Kidney Function

This week a story about inadequate hydration in US youth has gotten a fair amount of press. As a pediatric kidney doctor, I end up seeing these kids in my clinic, most often for stones. Getting these kids to drink enough liquid to keep calcium from getting together with other stuff to form crystals and rocks is tough. The biggest barriers come from the schools!

The first problem is lack of access to fluid. There are water fountains in the halls, but kids often do not like to drink from them. Also, a mouthful of water every hour or two is far less than most of these children need. We have a stock letter we send to schools allowing our patients to carry water bottles to class.

ToiletLoveThe next issue involves bathrooms. Carmines' law of physiology states, "You drink, you pee, you don't, you die." Our stock school note also asks schools to let our patients use the bathroom when they need to go. Too many schools have really short transition times between classes that do not give students time to use the restroom. Teachers can also be reluctant to allow their pupils to wander about the school unsupervised, even when pursuing a noble activity like urination.

My final issue also involves bathrooms. Too many students tell me that they do not want to go to the bathroom at school. They are often dirty, unpleasant, and sometimes unsafe. If we want our kids to drink enough fluid, then we need facilities where they can "recycle" that liquid. These facilities should be ones we would use ourselves, and not just in an emergency situation.

We evolved on the savannah where access to liquid was often unpredictable, so our kidneys can conserve water well, without immediate damage. Long-term effects of concentrating urine may occur, but kidney stones are a clear, early result. This is more than a matter of telling our offspring to drink more. It's a matter of making them able and willing to pee more.

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That Time Again: #NephMadness and #ISpyPhysiology

Mar 04 2015 Published by under Kidney Function

March, that time when our attention turns to kidneys! After all, the second Thursday of this month, March 12* this year, is World Kidney Day. Have you finished your shopping and planned your celebration yet?

LogoMarch also heralds the onset of NephMadness, an exploration of the kidney that pits advances in science and therapy against each other in a bracket format resembling a certain national basketball tournament. Regionals for 2015 came out on Sunday:

Each regional bracket was filled by an expert who provides a discussion of the match-ups, including a lot of background kidney physiology and pathophysiology. Click on over and read these excellent posts. Then click here to fill out your brackets; this year the event includes prizes beyond bragging rights!

What are you waiting for? No one can resist filling out those brackets!

*By the way, March 12 is also the date of my birth, making it a doubly special day this year!


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Giving Thanks

Nov 26 2014 Published by under Kidney Function

Soon we will all sit down and share a meal with family and friends, ostensibly to give thanks for what we have (or at least a day off). As you enjoy your traditions, I want you to give thanks for something else:


The patients I take care of, with various kidney diseases, cannot merely sit down and gorge as they want. After all, it's only one day and one (never-ending) meal. No, they will have to limit some foods, take their medications, and generally live their lives as they do every other day of the year. For some, misbehavior could result in discomfort. For others, a Thanksgiving eat-a-thon could prove deadly.

So when you go around the table and say what you are all thankful for, remember to at least think about functioning kidneys and the ability to pee.

It's great to urinate!

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When to Pee in the Cup

Sep 11 2014 Published by under Kidney Function

Screening urinalysis (UA), usually performed by dipstick in a physician's office, ultimately results in a lot of referrals for nephrologists. I am reviewing this topic, and I will have a series of posts about UAs over the coming weeks. First, I want to start with a poll about what is really recommended for healthy, asymptomatic children:

What are the current recommendations for screening urinalysis by the American Academy of Pediatrics?Next week I will reveal the answers from the crowd, as well as what the real answer is.

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Sep 06 2014 Published by under Kidney Function, Life of a Physician

It's been a dry week.

Zer0. Zip. Nada.

Today, the urine output box shows 46 mL overnight.

Less than an ounce, but an important sign of the return of kidney function.

Keep it up, kid.

Urine is golden.

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Another Topic to Video: Thrombotic Microangiopathies

Aug 25 2014 Published by under Kidney Function

My conversion of resident lectures to self-study videos continues with Thrombotic Microangiopathies.

These disorders are characterized by consumption of platelets and red blood cells with resulting anemia and blood clotting problems. Other organs can be affected, particularly the kidneys (duh-why else am I talking about it?). These disorders include hemolytic uremic syndrome (HUS) and thrombotic thrombocytopenic purpura (TTP).

I would enjoy hearing your comments about the video. Would an adapted version (with less attention on specific doctor-level stuff) be good for parents?

Let me know in comments below, please!

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