Metformin Guidelines

Metformin is one of the most useful drugs in patients with type 2 diabetes and yet its use in patients with CKD is limited by the perceived association with lactic acidosis. These concerns are due to the association of a prior biguanide, phenformin, with a marked increase in the rate of lactic acidosis. The mechanism for this appears to be reduced peripheral glucose oxidation and increased lactic acid which occurs with even small increases in phenformin levels. The drug was eventually removed from the market because of a number of fatal cases.

Metformin, in contrast, does not appear to be as closely associated with lactic acidosis. Most of the reported cases are in patients who would appear to have other reasons for lactic acidosis (although this case series including patients on dialysis that appears to be reasonably convincing and there are multiple smaller case series in patients on HD). A large meta-analysis of clinical trials if metformin showed no increase in the rate of lactic acidosis in patients on the drug. However, it should be pointed out that these trials did not include patients with advanced CKD.  Metformin is not protein-bound and is largely cleared by the kidneys so there is clearly accumulation of the drug in patients with CKD. However, it is unknown what the real "safe" level is and no studies can ethically be performed to establish this.

As a result, in general, guidelines regarding the use of metformin have been conservative. The insert for the drug suggests that it is contraindicated in individuals with a serum creatinine >1.4mg/dl (women) or 1.5mg/dl (men). Personally, I find these guidelines to be insufficient and frustrating because of course, a creatinine of 1.5mg/dl can mean entirely different things depending on the context (age, weight, race etc.) So it is gratifying to see that the diabetes associations have moved forward with newer guidelines.

The ADA published a paper with new guidelines for the use of metformin in 2011 incorporating eGFR. This paper also summarizes very nicely all of the evidence for and against the use of metformin in CKD. In summary, they suggest that for individuals with eGFR>45, metformin can be safely initiated. For those with an eGFR between 30-45, it can be continued with caution if it is already in use. Finally, it is contraindicated in patients with eGFR<
30. These guidelines make more physiologic sense and although they may still be too conservative, in this era of automatic reporting of eGFR, to me, it is the better approach to take.

Precision Nephrology

One of our attendings, Dr. Sylvia Betcher, PhD, MD gave an excellent presentation at our renal conference about genetic testing in renal diseases that she learned about at #KidneyWeek2015. There were so many good things I liked about her talk, that I want to share what I learned. On January 30th 2015, President Obama announced in his State of the Union address a Precision Medicine initiative. This will provide researchers in the biomedical field with the necessary tools to define preventive measures and treatment of disease by examining variability in genes, environment, and lifestyle of each patient. Precision Medicine relies on specific molecular and genetic information to classify a certain disease into subsets that allow consideration of focused therapies, which is currently being accomplished through GWAS (Check the #NephMadness genetic nephrology region bracket on GWAS here), whole gene sequence analysis via next generation sequencing (NGS) and VAAST (Variant Annotation, Analysis and Search Tool) which is used to identify damaged genes and their disease-causing variants in genome sequences. The president’s 2016 budget will provide $215 million to the various agencies including the NIH and FDA to accomplish his goals. The objectives of such initiative can be found here.

Most of the budget will go to cancer research and there is no mention of rare diseases or any particular hereditary or genetic disease. In the Nephrology world, are there any diseases in particular that need to be addressed? Yes, for instance Steroid Resistance Nephrotic Syndrome (SRNS), among many others. In this paper, a single-gene cause of SRNS was detected in 526 out of 1,783 families (29.5%), by examining 21 genes. The authors mentioned that screening of these genes is cost-effective and may avoid the undesirable side effects of steroids when a mutation is detected and potentially offer targeted therapy (for example with Coenzyme Q10 in cases of COQ2 nephropathy)

According to the NCBI Genetic Testing Registry as of August 2014, there were approximately 4,500 conditions for which genetic testing is available, many of which will have renal manifestations. Advantages to testing include providing specific therapies, allowing family counseling and to evaluate kidney donors in family members. Diseases that are being considered in Nephrology for genetic testing include: rare autosomal dominant interstitial nephropathies (UMOD, MUC1, REN), Syndromic and Polycystic Kidney Disease, Alport Syndrome and Congenital Anomalities of the Kidney and Urinary Tract (CAKUT). Additionally, I want to emphasize the fact that Genomics England (a company owned by the UK Department of Health) and Illumina (an American biotechnology company based in San Diego, California) have launched a $524M project to create a large genome database. Their plan is to sequence 100,000 whole genomes by 2017 focusing on rare diseases, cancer and infectious diseases. A nephrology consortium has been set up to provide renal patients for this ambitious project.

Let’s say we have screened our patients for congenital kidney diseases. Now what? We have to consider whether the results will influence any change in management, or perhaps we need to screen for extra-renal manifestations. I think that providing family counseling will definitively be helpful. It will also influence the decision on safety of kidney donation. Urine could be an excellent source of genetic information through DNA fragmentation which is a normal process in apoptotic cells to eliminate mutated, damaged or infected cells and is usually highly fragmented whereas in cancer cells the DNA maintains its integrity. So in conclusion, these are exciting times in Nephrology with precise genetic testing now a diagnostic option. Do you see yourself practicing Precision Nephrology in 10-20 years? Let us know what you think!

#NephMadness Increased MAP in Sepsis Haiku Deck

Increased MAP in Sepsis - Created with Haiku Deck, presentation software that inspires

Post by Hector Madariaga. Go to the AJKD blog NephMadness critical care in nephrology region to read more. Make your picks before March 22nd

#NephMadness Norepinephrine in Sepsis Haiku Deck

Norepinephrine in Sepsis - Created with Haiku Deck, presentation software that inspires


Post by Hector Madariaga. Go to the AJKD blog NephMadness critical care in nephrology region to read more. Make your picks before March 22nd

Is there a benefit in pre-transplant weight loss? #NephMadness

To complement the NephMadness Nutrition in Nephrology obesity match-ups, we thought a post on pre-transplant weight loss was timely. According to a recent report published in JAMA, more than one third of the US population are obese (BMI>30) with an estimated medical annual cost of $147million in 2008. Obesity causes heart disease, stroke, type 2 diabetes mellitus and certain types of cancer. According to a recent policy statement of ASCO, obesity is predicted to overtake tobacco as the leading modifiable cause of cancer in the United States in the near future.
In the Nephrology world, we are all aware of the survival advantage of obesity in dialysis patients with the so-called “reverse epidemiology” or “obesity paradox” (While obesity, hypertension and hyperlipidemia are indicators of high cardiovascular risk in the general population, in dialysis patients these conditions are associated with a survival advantage). This was demonstrated in several well-conducted studies (ref, ref, ref) in the United States and Europe.

But is there any survival advantage for obese patients while they are waiting for a kidney transplant? Obesity is not an absolute contraindication for transplant listing although some transplant centers do not evaluate patients with BMI >30-35 kg/m2. At our center, we recommend patients should aim for a BMI < 35kg/m2; however we have performed kidney transplants in patients with higher BMIs. Approximately 60% of kidney transplant recipients are overweight, which represents a 116% increase from 1987. But is BMI an accurate reflection of obesity in adults? The answer is no. The accuracy is limited and although a BMI cutoff of >30 kg/m2 has good specificity, it misses more than half of people with excess fat. Newer techniques to evaluate obesity include abdominal circumference, waist to hip ratio, hydrostatic weighing and body fat measuring.

There are concerns about allograft survival, weight gain after kidney transplantation and wound healing. Two retrospective analyses in obese patients undergoing kidney transplantation reported higher rates of delayed graft function, acute rejection, peri-operative complications and worse renal function with higher BMIs.
On the other hand, there is evidence that higher BMIs do not influence outcomes. A study of >164,000 patients demonstrated that low pre-transplant BMI, low pre-transplant serum creatinine (which could be due to sarcopenia), were associated with worse post-transplant outcomes. Bariatric surgery is becoming more popular prior to kidney transplantation and according to this study of USRDS data that evaluated the safety of the procedure, bariatric surgery provides substantial weight loss to kidney recipients. However, it also reported more peri-operative complications and increased mortality in comparison to patients undergoing the same procedure without kidney disease. Significant pre-transplant weight loss (>10kgs) may be a risk factor for peri-operative complications, particularly wound problems. Another study reported that weight loss during transplant listing had no effect on long term outcomes after transplantation and rapid weight loss was associated with subsequent post-transplant rapid weight gain. According to this analysis, the rate of mortality before and after transplantation is unchanged despite weight loss.

In conclusion, there is no evidence that weight loss before transplantation improves long-term outcomes following transplantation although much of the evidence is retrospective and observational in nature. The absence of significant central obesity certainly helps with wound healing and it is intuitive that a ‘healthy weight’ augers well for long term morbidity. How we measure this ‘healthy weight’ however is debatable including where BMI fits into this assessment, if at all.

Hector M. Madariaga,
SUNY Upstate Medical University

Scleritis and Kidney Disease - More than meets the eye...

Scleritis is a severe inflammation involving the deep episclera and sclera. Symptoms include moderate to marked pain, hyperemia of the globe, lacrimation, and photophobia.

Scleritis tends to recur and is frequently associated with an underlying systemic illness, such as rheumatoid arthritis, lupus, IgA vasculitis, polyarteritis nodosa and granulomatosis with polyangiitis.   A few cases are infectious in origin and about half of the cases of scleritis have no known cause.

 In Renal Grand Rounds on Tuesday, Patrick McGlynn presented a case of 30 year-old healthy female who came to clinic complaining of pain and redness on her right eye. Blood pressure was elevated at 155/90 mmHg. On exam, right eye had redness on sclera. No involvement of left eye. No papilledema on fundoycopic exam. Ophthalmology was consulted and thought the exam was consistent with sectoral scleritis inferotemporally on right eye (representative figure above). Labs showed a creatinine of 1.79mg/dL and urine sediment analysis revealed few WBC casts. Based on acute presentation with renal failure and active urine sediment, a kidney biopsy was performed, revealing IgA nephropathy.

 Ocular involvement in patients with IgA nephropathy is infrequent, but may lead to uveitis, episcleritis, scleritis or retinal vasculitis. For sure worth keeping an eye…

Accepting Applications to the Origins of Renal Physiology Course

Nate Hellman, in front of the "Kidney Shed" at Mount Desert Island

The National Course for Renal Fellows: Origins of Renal Physiology course will run from August 30 to September 5, 2015 at the Mount Desert Island Biological Laboratories. Each year renal fellows come to the Acadia coastline to explore the fundamentals of renal physiology with a distinguished faculty drawn from top institutions around the world. Funded by the National Institutes of Health (NIDDK), the course covers the costs of instruction, food and housing for the week.

The application link is here. Applications will close at the end of April.

"The MDIBL Renal Fellows course gave me the opportunity to learn renal physiology from the experts in their fields, in a place where so many important discoveries were made by the giants of nephrology. Collaborating with my peers from programs all over the country, we re-created the experiments that helped characterize ENaC structure and function, osmoregulation, and the complex proximal tubular in a supportive yet intellectually stimulating environment. And when our lab presentations were finished, we enjoyed Acadia National Park and the coast of Maine, by foot and by bike, making great new friends along the way." - Jeffrey William, Fellow, Beth Israel Deaconess Medical Center

This course is a fantastic offering and was life changing for myself and I know many others. Where else can you go to learn about the kidney with fantastic faculty and fellows from all around. This was where I met the late Nate Hellman back in 2008, founder of RFN. You can read some nice blog posts from Nate from the actual course here and if you scroll down here. I would not only highly recommend this course but I would urge you to go. Now that it is supported by the NIH you really have no excuse not to go.

Matt Sparks

#NephMadness Furosemide Stress Test Haiku Deck #CCRegion

Furosemide Stress Test - Created with Haiku Deck, presentation software that inspires

Post by Hector Madariaga. Go to the AJKD blog NephMadness critical care in nephrology region to read more.

Is Matching at the HLA Epitope Level the Holy Grail of Longer Graft Survival?

All HLA antigens are composed of strings of several polymorphic sites, which may serve as targets, or epitopes, for antibody binding. An important consideration is that HLA antigens have multiple epitopes that can be recognized by specific antibodies. The current nomenclature of the HLA system does not take into account the nature or identity of these epitopes. Elucidation of three-dimensional molecular structures and amino acid sequence differences between HLA antigens has made it possible to define the structural basis of HLA epitopes (reviewed by Tambur, Claas AJT 2015).

Why could this be important?
For certain HLA phenotypes a given mismatch has no or few mismatched epitopes and for other phenotypes, the same HLA antigen has many mismatched epitopes and is therefore, structurally highly incompatible. Altogether, the degree of structural compatibility of a donor HLA mismatch is largely determined by the HLA type of the recipient. Therefore, the level of epitope match may help identifying the best compatible donor. Furthermore, it may identify epitopes that are most immunogenic and lead to a greater risk of antibody generation post-transplant (Wiebe et al. AJT 2013).

How can you do this?
HLA Matchmaker, a computer algorithm available for free at www.hlamatchmaker.net, determines histocompatibility at the epitope rather than antigen level. Therefore, it can provide an estimate of the degree of epitope matching or mismatching.

Who would benefit the most?
Highly sensitized patients with difficult matches and younger patients to minimize risk of de novo DSA development post-transplant.

#NephMadness Early Goal Directed Therapy Haiku Deck #CCRegion

Early Goal Directed Therapy - Created with Haiku Deck, presentation software that inspires

Check out the NephMadness Critical Care Nephrology region.

Post by Hector Madariaga