musings of a salt whisperer
Notes from Dr. RW: Nonhepatic hyperammonemias: “—may be underappreciated causes of encephalopathy in hospitalized patients. I recently blogged one example of a nonhepatic hyperammonemia…”
I guess PBFluids is part Dr. Boring and part Dr. Didactic.
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| From A Cartoon Guide to Becoming a Doctor |
The Scientific Registry of Transplant Recipients (SRTR) prepares an Annual Report in collaboration with the Organ Procurement and Transplantation Network (OPTN) on the state transplants in America. In 2008 there were fewer transplants done than in the previous year. Kidney transplants peaked in 2006 at 18,059 and have fallen for two straight years.
The total number of organs transplanted decreased from 27,586 in 2007 to 27,281 in 2008. This was an overall decrease of 305 organs transplanted (1.1 percent), including 91 (1.4 percent) fewer living donor transplants.
Here is the data on kidney transplants displayed graphically. Note the ever increasing demand for transplant as represented by the number of patients on the waiting list:
Here is the same data from the USRDS:
At journal club this morning I mentioned my patient and polled the room to see who would have sent her for a kidney biopsy. Our fellowship director did his best Sarah Palin impersonation with, “Would I biopsy her? My answer isn’t no, it’s hell no.”
Going around the room all 5 fellows and both of the attendings were in agreement that they would not do the biopsy. This is also in agreement with the first comment on Facebook. It seems that no one would biopsy this patient.
In the best traditions of Web 2.0, let’s do an informal survey. Ill post the results next week along with a comprehensive summary of membranous nephropathy in pregnancy (the librarians are hard at work pulling articles as I type).
Today a woman came to see me who was 6 months pregnant. She was seeing me for a second opinion. During her first prenatal visit her OB discovered 4+ proteinuria and the patient was referred to nephrology. A 24-hour urine subsequently documented 7 grams of proteinuria with excellent renal function. She had a serum creatinine of 0.4 mg/dL.
The serologic work-up was negative. No ANA, negative ANCA, no viral hepatitis, compliments were not decreased, HIV was negative. Antiphospholipids were not checked.
The nephrologist then sent her for an ultrasound-guided renal biopsy, which showed membranous nephropathy.
Now she is six months pregnant and doing well. She has a lot of lower extremity edema but no other symptoms. I advised no specific therapy at this time and close, continuous follow-up.
The whole time I’m seeing her I’m thinking would I have biopsied her? What are the indications for a kidney biopsy in a pregnant patient?
I love it when Dr. Google has just what you wanted to know:
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| And it’s NDT, so hastle free PDFs. Yay! |
From the introduction:
Indeed one group recommend no modification of the indication for renal biopsy in pregnancy and suggest that all pregnant women with abnormalities in urinalysis indicative of renal disease should undergo renal biopsy to guide treatment [4], but this is not standard practice. Although it has been established that there is no greater risk of complications of renal biopsy in pregnancy, the consequences to the mother and fetus of post-biopsy haemorrhage could be severe.
The article reviews 20 women who had kidney biopsies during pregnancy and 75 who had post-natal biopsies.
Biopsies during pregnancy (N=20)
Indications for the biopsy:
The pregnancies resulted in 17 children, 2 miscarriages and one still birth. The average gestation at delivery was 34 weeks. The biopsies all went well with only one complication, mild hematuria that resolved spontaneously. The biopsy changed therapy in 9 of the patients.
Biopsies after pregnancy (N=75)
Indication for the biopsy:
By my count that is only 69 patients, not sure what happened to the other 6.
The authors presented follow-up data on 47 patients who followed up within their hospital system. The patients who received follow-up tended to be patients with more severe disease, as patents with mild disease were discharged to primary care.
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| Grey is bad. Black is better. |
The authors conclude that the modern kidney biopsy is generally safe during pregnancy and should be performed in the following circumstances:
In the first trimester
Structurally normal kidneys and:
- an active urinary sediment or
- nephrotic syndrome or
- unexplained CKD (with proteinuria and no evidence of scarring) or
- those with renal impairment and proteinuria in the context of systemic disease or positive autoimmune serology
We feel a diagnosis at this stage of pregnancy is of benefit to guide treatment and allow an informed discussion of the risks:benefit ratio of continuation of pregnancy.
In the second trimester
Renal biopsy should be reserved for those with:
- unexplained nephrotic range proteinuria
- progressive CKD and renal disease in the presence of active systemic disease
Interesting, so by these authors recommendations the biopsy was indicated (she has nephrotic syndrome), despite the fact that it didn’t change her therapy. Good to know.
Crazy
I just received the following e-mail the ASN
On Tuesday, March 22, 2011, your HighWire sites began receiving a flood of unusual requests for PDFs. What we observed was that a single click to request a PDF of an article would result in multiple requests for the PDF being sent to your sites. In some cases a single request was being multiplied more than 100 times. This caused an overload on the systems responsible for serving PDFs. Early impacts, around 5:00 to 6:00 AM (PDT), were felt as slow response for PDF serving but as the day moved on and traffic on the sites rose the impacts increased until the whole sites were slow as the PDF requests backed up, in the 8:00-9:00 AM (PDT) hours.
Our first response was to turn off access to the PDFs so that the sites would continue to serve other pages well. This was effective and allowed us the breathing room to analyze the traffic more carefully, and we were able to localize the large majority of these multiple requests as coming from users of the most recent version of Google’s Chrome browser, which was just updated in the last few days.
At approximately noon on Tuesday we blocked the use of the most recent version of Chrome from all H20 sites. We regretted taking this action (I use Chrome as my browser, too) but it was the way we could restore full service to more than 90 of your users and still allow the other 10 the option to choose a different browser and receive full service as well. Chrome was blocked from approximately noon until 5:15 PM, when we were able to deploy a fix for the Chrome bug.
During the time that Chrome was blocked we were able to perform diagnosis and to determine that for many PDFs, Chrome was requesting the file 32Kbytes at a time. What this mean is that for some large PDFs a single click of the mouse was generating 11,000 requests for the PDF. We were also able to determine how to prevent Chrome from making these requests and we built a fix that was deployed t0 all H20 sites at 5:15 PM.
At the time of this writing all sites have been restored to full function and all users are receiving full service. We have no reason to believe this problem will recur and we deeply regret the impact that the Chrome update had on you and your readers.
Wow, that’s cool. Both that they fixed it so fast and that they cared enough to send a note. Go Team ASN!
In February, for the first time, Facebook sent more readers to PBFluids than Google. I believe this is from the ASN Kidney News now linking to my posts on their Facebook page. It’ll be interesting to see if the trend continues or if it was a one month aberration.
In response to the increasing importance of Facebook to my readership I have created a PBFluids facebook page. A new experiment with this medical blog unfolds. Exciting.
Nephron Power has a fine post on the top ten reasons the kidney’s are the best organs. Here is my riff:
The lungs serve to maintain the composition of the extracellular fluid with respect to oxygen and carbon dioxide, and with this their duty ends. The responsibility for maintaining the composition of this fluid in respect to other constituents devolves on the kidneys. It is no exaggeration to say that the composition of the body fluids is determined not by what the mouth takes in but what the kidneys keep: they are the master chemists of our internal environment. Which, so to speak, they manufacture in reverse by working it over some fifteen times a day. When among other duties, they excrete the ashes of our body fires, or remove from the blood the infinite variety of foreign substances that are constantly being absorbed from our indiscriminate gastrointestinal tracts, these excretory operations are incidental to the major task of keeping our internal environments in the ideal, balanced state.
When I talk about toxic alcohols causing anion gap metabolic acidosis I emphasize that these patients have large anion gaps. When you see an anion gap of 16 or 20 think uremia and lactic acid, not methanol. The cases I have seen have almost all had gaps greater than 25 and typically they run in the 30s.
But I have never heard of or seen a gap as big the one that came into the ICU this week-end:
To summarize the data from above. A patient was admitted with an anion gap of 65 that went up to 70 in the next 6.5 hours. I can visualize the ER doc reading the first chemistries, freaking out and re-ordering them, assuming that if the anion gap is greater than the chloride it must be a lab error, hence the repeat labs at 150 minutes after the first set.
Think about that, the anion gap was larger than the chloride concentration.
What kind of alien infestation causes numbers like that?
So when working up a large anion gap one tries to explain the anion gap. The lactic acid was only 34.5 mmol/L. So this patient has the highest lactic acid ever, yet it only covers half the gap. She also had serum ketones that remained positive at a 1:8 dilution and a creatinine of 14.
So is that it? Lactic acidosis, ketosis and uremia for an anion gap of 70? I sent off a D-lactic acid and a 5-oxoproline level, cause what the hell, when’s the next time I’m going to see an anion gap of 70. A toxic alcohol screen was sent.
To compete the picture the ABG was: 6.95/13.4/187 with a measured bicarb of 3. With numbers this crazy a trip to the Henderson-Hasselbalch formula is probably not a bad idea:
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| MedCalc has a sweet HH calculator |
So 6.97 is pretty close to the 6.95 measured, so no lab error at least in the ABG. Running Winter’s formula (1.5 x HCO3) + 8 ±2 gives a predicted pCO2 of 13, so no respiratory component to the metabolic acidosis.
The next step is to look for toxic alcohols while waiting for the assay to come back from toxicology lab at Children’s Hospital of Michigan. The osmolal gap calculation should be greater than 10 in the presence of methanol, isopropyl alcohol or ethylene glycol. The measured osmolality was 327.
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| MedCalc also has a sweet osmolar gap calculator |
So no significant osmolal gap rules out a toxic alcohol. This was confirmed by the toxicology screens that eventually came back. Given the anuric renal failure, profound intractable acidosis and unknown anions still unaccounted for we initiated CVVHD. You can see the effect that had on her bicarbonate and creatinine.
Michael Hyatt has an a good read about the costs of blogging and advises against getting bogged down in details about design, custom software and hosting. Find a way to cut through that BS inorder to start writing.
He recommends WordPress.com, premium version for $12-17 a year. He doesn’t say why he would choose that over Blogger (the host of PBFluids).
Today I received my bill for blogging for the next year here at PBFluids:
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| Blogging. Total bargain. |
$10. That’s all.
Here is Dr. Ves on Medical Blogging. He is actually quoting Seth Godin and Tom Peters. This best sums up my feelings on blogging:
It doesn’t matter if anyone reads it. What matters is the humility that comes from writing it. What matters is the metacognition of thinking about what you’re going to say.
No single thing in the last 15 years professionally has been more important to my life than blogging. It has changed my life, it has changed my perspective, it has changed my intellectual outlook, it’s changed my emotional outlook.
And it’s free.