Part of the dogma of evaluating iron deficiency in patients with anemia is that after a transfusion the iron indices are altered. Over and over the question comes up…
How long after a transfusion do you have to wait before checking to see if the patient is iron deficient?
Well Jabri, my current fellow went to the literature and found this reference. It looks like the answer is you should be safe 48 hours after the transfusion. This surprised me, I expected the acute effects of the transfusion to persist longer than that.
Abstract from the paper:
The effect of transfusion of packed red blood cells on serum iron level, total iron-binding capacity, and transferrin saturation was studied. Samples of blood from 37 hemodynamically stable patients were obtained for analysis at various intervals following the transfusion of packed red blood cells. In 10 patients with possible iron deficiency, a significant rise in serum iron level and transferrin saturation occurred during the 24 hours following transfusion, which persisted at a marginally significant level up to 36 hours. In the remaining 27 patients, a significant rise was also noted in serum iron level and transferrin saturation results, but the rise did not persist beyond the 24 hours after transfusion. No change in total iron-binding capacity was noted in either group. These data show that the diagnosis of iron deficiency (based on a transferrin saturation of < 0.16) might be missed if iron studies are performed on patients within 24 hours following packed red blood cell transfusion. Therefore, if serum iron studies are obtained for patients suspected of having iron deficiency anemia, these studies are best done on blood samples obtained before blood transfusion.
Only a nephrologist ever capitalizes Fluids and Electrolytes.
I am so excites. I get to give the first lecture on July 1. I love the nervous energy that comes with fresh second years and new interns still getting used to the length of their newly lengthened coats.
I am working over my standard F&E Emergencies. I am putting together a new handout designed to be kept in the pocket. While working on the talk I re-found this classic review of diuretic therapy by Craig Brater. Dr. Brater was elevated to Dean of Indiana University Medical School right before I got married at the end of my residency. We had our rehearsal dinner at this Columbia Club on the Circle. I bumped into Dr. Brater right before dinner and congratulated him on becoming the dean.
Our second year resident set the bar high by doing a great overview of calcium metabolism. Here is his handout. All it was missing was some evidence based data.
This noon comference was not done by me but by Dr. Steigewalt. The whole team was there.
Dr. Steigerwalt provided some great handouts:
We are going to study renal and patient survival in our CKD clinic. One of our team members who is charged with creating the data capture form wanted to look at prior form. So here it is.
Today’s journal club was on Aliskiren (Tekturna)combined with Losartan versus Losartan alone from the NEJM and Benazepril + Amlodipine (Lotrel) versus ACEi + HCTZ (Lotensin HCT) from KI. Both studies use change in albuminuria for the primary endpoint.
The Aliskiren study had an expected outcome. The shocker would have been if it had gone the other way. The surprising thing was how close they came to showing an actual decrease in progression (p=0.07) in only 6 months and with only 600 patients. Looks like aliskiren + ARB is a lock to slow the progression to doubling of creatinine and prevention of dialysis.
The Guard study was a surprise because the old generic lowered albuminuria more than the new hotness Lotrel. A lot of spin in the discussion on why that may have occurred.
One of my (soon to be former) fellows wanted a copy of this work-sheet handout on electrolyte free water clearance.
Yesterday we discussed the problem with the curvilinear relationship between gfr and creatinine and how the MDRD equation dispenses with this problem. Today we will go over a handout introducing GFR, MDRD and how to manage them, including referral to a nephrologist.
Additionally I want to do my canned acute renal failure lecture. This lecture has been made obsolete by the recent ATN data and data from Vanderbilt so it will need to be revised.
I love it when some of the arcane nephrology knowledge makes headlines. When I heard NPR covering hyponatremia I almost cried. I am training for a half marathon in October and so I have been thinking about this topic.
Almond, Et al’s study published in the NEJM looked at 488 blood samples from 766 runners recruited from the 2002 Boston Marathon. They found post-race:
- Average sodium 140±5 mmol/L
- 13% had a sodium <>
- 3 runners had Na <>
When they looked at predictors of hyponatremia, univariate predictors included:
- Female gender (p<0.001)
- Lower BMI
- Fewer prior marathons (p=0.008)
- Slower training pace (p<0.001)
- Longer race duration (p<0.001)
- Hydration frequency (p<0.001)
- Hydration volume (p=0.01)
- Urination during the race (with more frequent voiding having a higher risk of hyponatremia) (p=0.047)
- Weight gain during the race (p<0.001)
Of note use of sport drinks compared to pure water made no difference. In the multivariate analysis, hyponatremia was associated with:
- weight gain
- longer racing time
- body-mass index of less than 20
Of note the female gender falls out in the multivariate analysis as it likely was accounted for both by the longer running time and lower BMI.
In the discussion the authors mention that most sport drinks have only 18 mmol/L of Na.
On Monday one of our interns gave a lecture on the range of renal pathology possible found with lupus nephritis.
This was a follow up on her lecture on the renal manifestations of lupus nephritis by WHO criteria. After her lecture we went down to bowels of the hospital to look at the kidney biopsy we had done on Friday on one of our patients with lupus.
Also on Thursday I lectured the house staff on Nephrogenic Fibrosing Dermopathy, Acute Phosphate Nephropathy and Contrast Nephropathy. Renal adventures in imaging.
On Friday the 13th we completed Acid-Base disorders. As part of acid-base we talked about the anion gap. This article
in CJASN on the anion gap was wonderful.