Nice perspective on dietary causes of gout by Gary Taubes.
Contrast and residual renal function
In a previous entry I reviewed the iPhone app PubMedOnTap. I used this application to find articles regarding the question of whether iodinated radiocontrast media harms residual renal function for patients on dialysis. I came up with two “hits.”
- The first is an article by Paul Palevski’s team at Penn.
- The second is by Janousek et al. from the Czech republic.
The Palevski study is a retrospective analysis of PD patients with residual renal function who underwent coronary angiograms. They compared residual renal function after the angiogram to previous residual renal function. They also looked at mortality, change of modality and peritonitis. They created a control group composed of patients matched for time of initiation of PD, age, and diabetic status.
29 patients met the enrollment criteria. Residual renal function was assessed an average of 14.7 weeks following the procedure. 1 patient became permanently anuric following the angiogram.
The average loss of renal function for the cases was 0.09 ml/min/month versus 0.07 ml/min/month for the controls (p=0.53). Average decline in residual renal function for PD patients is said to be 0.1 mL/min/month.
5 patients had no residual renal function measured after the angiogram and a medical record review could not document why this happened. They were censored from the final analysis.
The Janousek study is a more rigorous design, as it is controlled. They did a matched cohort study of hemodialysis patients who underwent a endovascular procedures and matched them to similar patients who did not receive contrast.
All the participants had to have at least 500 mL of urine production per day.
The contrast patients received an average of 99 mL of iodixanol (isoosmolar contrast, Visipaque) with a range of 60-180 mL.
The authors specifically state that
Our aim was not to evaluate the immediate effect of contrast medium on residual renal function during the several days after application. Rather, we wanted to evaluate its long-term clinical effect. This is why we compared the volume of daily diuresis and RREC 3 months before and 3 months after ICA administration.
They found no difference in the rate of loss of residual renal function whether they measured it by urine volume (p=0.855) or creatinine clearance (p=0.573).
Only clinically stable patients with no serious concomitant disease and who survived for a 6- month follow-up period with an unchanged dialysis strategy were evaluated.
In the discussion the authors mention three other articles on the same subject:
They found two in NDT in addition to the pavlesky article. None showed a deleterious long term effect of contrast.
- The first was a prospective trial by Dittrich el at. of 10 peritoneal dialysis patients with 8 patients as controls. They found a temporary drop in residual renal function that was erased after 30 days.
- The second was a prospective cohort trial by Morrane et al. of 72 peritoneal dialysis patients, half of which were exposed to contrast. After two weeks there was no difference between the two groups or from baseline figures in regards to CrCl, urine volume or residual renal function.
How to make a cool clinic diagnosis
I had a great case yesterday in clinic.
The patient was a 55 year old woman with HIV and a chief complaint of gradually climbing creatinine. Among her medications were Truvada and Norvir.
Truvada is one of three brand name drugs that contains tenofovir:
- Viread: tenofovir
- Truvada: emtricitabine-tenofovir
- Atripla: efavirenz-emtricitabine-tenofovir
I will follow up with the patient in the month. Hopefully she will do well.
Great web service for making booklets
My favorite way to lecture is to pass out a personally written chapter on the subject and then collectively read the hand-out. I call this lecturing “Seder-style” named after the ritualistic dinner of the Jewish holiday Passover.
The booklets have four pages on each sheet of paper but you need a computer program to reorder the sheets so the booklets come out right. I used to have a print service that did this for me but it stopped working when I upgraded to Snow Leopard. I found this web service BookletCreator which does a great job with this.
Here are the original PDFs I uploaded:
Here are the bookletized PDF the website created:
Perfect.
UPDATE: No longer free.
PubMed on Tap for the iPhone: the NLM in your pocket
Last week at the end of a morning conferance there was an impromptu discussion of the problem of residents ordering IV contrast for patients with acute kidney injury. The residents see a patient on dialysis and feel that its open season for contrast.
As part of the discussion one of the attendings mentioned this is also a problem with his PD patients with residual renal function and the residents need to know that contrast should be avoided in these patients to preserve residual renal function. I mentioned that actually the data doesn’t support the common sense notion that contrast accelerates the loss of residual renal function. Immediately all eyes were on me and the consensus was that no one else had seen that data and that I was way off the reservation. Pretty uncomfortable place to be.
I had buttoned holed Paul Palevsky at the 2006 ASN Renal Week after a talk on contrast nephropathy and in that hallway conversation he had mentioned that he had just finished research on this vary question. he only reason I remember it was that the results were so counter intuitive. Contrast has no measurable affect on residual renal function. I had actually never seen the article but now I had put up or shut up.
After the conference I had to run to an outside hospital but I stopped at a Tim Hortons (the best thing to come out of Canada since Douglas Coupland) and fired up PubMed on Tap (PMT).
PMT is an app dedicated to adapting the PubMed database to the constraints of a mobile platform. I used an app by the same name on my old Treo. Adding Palevsky as author, and then contrast and residual renal function as text words.
Bingo! One article:
I then did a less specific search by dropping the author name and found a higher quality study:
I was able to send the references to my colleagues right from the application. Sweet.
Great resource on potassium
kind of an “everything you wanted to know about potassium but were afraid to ask.”
I especially love the two Nobel prizes in the top corner. Pauling is one of only four people to win two. In an alternate universe Linus got a couple of breaks to beat Watson and Crick to the structure of DNA. In that universe he has three Nobels and walks around like Michael Phelps.
What are the top nephrology stories of the last decade?
As we come to the end of the naughts, we naturally reflect back and think about how far we have come from in the last ten years. Here is my quick list:
- MYH9 gene for ESRD
- The failure of the normalization of hemoglobin and the wholesale reevaluation of ESAs
- The rise of aldosterone and its importance in hypertension and renal disease
- the failure of dialysis dose to improve out come in both chronic (HEMO) and acute dialysis (ATN).
- FGF-23, hey a whole new hormone and a major advancement in renal physiology
- Re-emergence of home dialysis
- Problems with the definition of CKD and the problems with eGFR
- discovering the antigen in idiopathic membranous nephropathy
week-end call and a pair of crazy numbers: Glucose and Calcium
Calcium
The other crazy number was the most severe hypercalcemia I have ever seen. The calcium was 18 mg/dL with an albumin of 3.7 g/dL. The patient is a kidney transplant recipient who was recently seen in the outpatient clinic with hypocalcemia. His calcium was 6.5 and his calcitriol was increased from 0.5 mcg to 1 mcg twice daily. He was also continued on his calcium carbonate.
The other pertinent calcium labs:
- PTH: 3.2 pg/mL
- Vit D 1,25 dihydroxy: 36 pg/mL
- SPEP/UPEP: unremarkable
- PTHrp: pending
Cast Nephropathy and plasmapheresis
Does removal of the light chains with plasmapharesis reduce the severity of cast nephropathy? We know that renal failure is a terrible prognostic factor in multiple myeloma so fixing acute renal failure is important.
Renal failure comes in many different flavors with myeloma:
- Light chain deposition disease
- Heavy chain deposition disease that I have never seen but Steve Rankin had a case as a fellow.
- Amylloidosis
- Hypercalcemia
- Cast nephropathy
Though not randomized this recent article from KI should be of interest (Thanks Kyste):
Leung et al. Improvement of cast nephropathy with plasma exchange depends on the diagnosis and on reduction of serum free light chains. Kidney Int (2008) vol. 73 (11) pp. 1282-8.
Highest urine urea ever
Just saw a urine urea of 1,019 mg/dL. I can’t remember ever seeing one over 1,000 before. The FE Urea was 55% in a urosepsis induced AKI.