Posts

Posted on

Calculating the urinary microalbumin to creatinine ratio

One of my high volume referring doctors uses a lab which does not calculate the microalbumin to cr ratio. It always stops me in my tracks when I see the values.

  1. To convert microalbum and urine creatinine to the useful ratio first make sure both values are expressed as mg/L or mg/ml
  2. Divide the microalbumin concentration by the creatinine concentration
  3. Multiply the resulting ratio by 1,000 to get mg albumin over grams creatinine
For example a patient had the following labs:

Microalbumn urine 5.6 mg/dL

Creatinine urine 91.2 mg/dL

Dividing the albumin by cr gives: 0.061

Multiply that by 1,000 to get 61 mg albumin/g creatinine

Posted on

Hemoglobin A1c of 18.6

18.6!
That corresponds to an average blood sugar of 486!
Six months and 1,500 mg of metformin later it is down to 8.4% corresponding to an average of 194. That 18.6 has got to be an error. Right? Right?
Unfortunately for her GFR is 30 mL/min.
No metformin for you.
Posted on

iPhone, Android: Fight

Different data from the iPhone, Blackberry: Fight! from a few months ago but the same conclusion.
This battle is over! And the iPhone has won.
From Larvalabs:

Our two best selling games have been ranked and are currently ranked pretty highly on that hard to find list of paid apps. RetroDefense was #1 for a while and is currently around #12 with a perfect 5 star rating. Battle for Mars is currently #5 overall with a 4.5 star rating. Both of these games are selling for $4.99, which is on the upper end of the price range. Finally, both of these games have been featured by Google in the market app and on the Android website. So with all this in mind, here’s our daily Android sales for this August (these numbers include sales from our other two apps, but they barely register):

That’s a $62.39 daily average. Very difficult to buy the summer home at this rate.

Posted on

So how much do we spend on routine daily labs?


Apparently a crap load:

Several studies have identified the overuse of daily lab testing and how certain interventions can effectively reduce tests ordered. A study by Miyakis et al. examined the effects of disclosing lab test costs on the frequency at which healthcare providers ordered these tests. 24,482 laboratory tests were ordered before the intervention (mean 2.96 tests/patient/day). Among those, roughly 70% were not considered to have contributed towards management of patients (mean avoidable 2.01 tests/patient/day). After costs of tests were disclosed, the avoidable tests/patient/day were significantly decreased (mean 1.58, p = 0.002), but containment of unnecessary ordering of tests gradually waned during the semester after the intervention. (1) A study by Kumwilaisak et al. examined how the implementation of formal guidelines effected how laboratory tests were ordered. 1,117 patients were enrolled. After the institution of the guidelines, the number of laboratory tests decreased by 37% (from 64,305 to 40,877). Furthermore, this result was still present at 1 year. (3)

Posted on

Adrian Izhack Katz August 3rd, 1932 to August 17th, 2009


Dr. Katz was my mentor in the nephrology clinic my first year of fellowship. It was his last year of clinical work at the University of Chicago. He was also the supervising attending during some of my dialysis rotations. That rotation was liking being a traffic cop for inpatient dialysis. It is also where I got my twitter handle, @Kidney_boy. It was my beeper salutation.
He was a master of clinical medicine but we came at it from opposite directions. He was finishing and I was starting. He wanted to impart fatherly, philosophic reflections. I was hungry for raw data. I was racing to fill my head with facts. I wish I had an opportunity to spend time with him after I had matured.
Some memorable moments with Adrian:
  • We had just finished clinic in the DCAM and were walking back to the nephrology section. We often would go to his office to discuss something but this time he invited me into a lab. He turned on a Bunsen burner and made two shots of Turkish Coffee. Spending those moments drinking fresh coffee in the lab was the single coolest teacher-student moment of my life.
  • My wife and I had twins while we were in Hyde Park. Only two professors came over for the Bris on my birthday, Adrian Katz and Pat Murray.
  • Adrian and Miriam invited my wife and I over to his house for Passover. We brought our 6 month old twins. I remember being terrified of what they would break. The Katz’s were wonderful hosts and it was like going to the Wizard of Oz for dinner.
  • I remember his office. It was a beautiful large office with great built in bookcases lining one wall. The cases were full and every second or third book had a small yellow sticker. For months I had been meeting him in there. I had noticed the dots but assumed it was just a personal filing system. One day he asked me if I knew what those dots meant. I shrugged. He explained that a dot represented a book or chapter he had written. It was a mind boggling accomplishment, you were literally faced with a wall of academic achievment. I have written textbook chapters. For me it is about as easy as coughing up a lung. Amazing.
  • We were talking about intradialytic hypotension. How could we dialyze this patient without resorting to CVVH and a transfer to the ICU. I mentioned cold dialysate and he said that it is effective but patients don’t like it. My eyes widened like saucers and I said:

“I didn’t know that patients could feel the cooler temperature.”
Adrian replied, “You could fill an ark with what you don’t know.” And then started laughing uproariously. When he finally regained composure, he had tears in his eyes. He explained that he had once had a mentor who had used that same joke on one of Adrian’s peers. It was such a happy memory for him that he couldn’t contain it.

University of Chicago has a nice obituary.

He was a respected teacher.
The world is a shade paler without him.
Found a photo deep in the hard drive from that Seder:

Update from 2014, found another great photo

Posted on

Another one bites the dust: TREAT is negative

Darbepoeitin meets a similar fate as epoetin alpha in CKD patients. Here is the press release from the trial onset, a more opportunistic time:

Amgen Inc. (Nasdaq:AMGN), the world’s largest biotechnology company, today announced that the company has initiated a landmark trial to evaluate the impact of treating anemia on cardiovascular outcomes in patients with chronic kidney disease (CKD) and type 2 diabetes. TREAT (Trial to Reduce cardiovascular Events with Aranesp(R) (darbepoetin alfa) Therapy) is one of the largest clinical trials in the company’s 25-year history. The TREAT study design as well as additional Sensipar(R) data was presented at the American Society of Nephrology (ASN) annual meeting in St. Louis.

“Current research suggests that anemia is an augmenter of cardiovascular risk in individuals with CKD and type 2 diabetes,” said TREAT lead investigator Marc Pfeffer, M.D., Ph.D., chief of medicine at Brigham and Women’s Hospital and a professor at Harvard Medical School. “TREAT will be the definitive study to determine if treating anemia with Aranesp does, in fact, lower the risk of death and non-fatal cardiovascular events in individuals with CKD and type 2 diabetes.”

TREAT is an international 4,000 patient, multicenter, randomized, double-blind, placebo-controlled trial. The primary endpoint of TREAT is a composite index of time to mortality or non-fatal cardiovascular event, including myocardial infarction, myocardial ischemia, stroke and heart failure.

The rational for TREAT was published in the American Heart Journal. From the abstract:

BACKGROUND: Patients with chronic kidney disease (CKD) have a high burden of mortality and cardiovascular morbidity. Additional strategies to modulate cardiovascular risk in this population are needed. Data suggest that anemia is a potent and potentially modifiable risk factor for cardiovascular disease in patients with CKD, but these data remain unsubstantiated by any randomized controlled trial (RCT). Furthermore, the clinical practice guidelines for anemia management in patients with CKD are based on limited data. The need for new RCTs to address critical knowledge deficits, particularly with regard to the impact of anemia therapy on cardiovascular disease and survival, is recognized within the guidelines and independent comprehensive reviews of the existing published trial data.

STUDY DESIGN: The Trial to Reduce Cardiovascular Events with Aranesp (darbepoetin alfa) Therapy (TREAT) is a 4000-patient, multicenter, double-blind RCT, designed to determine the impact of anemia therapy with darbepoetin alfa on mortality and nonfatal cardiovascular events in patients with CKD and type 2 diabetes mellitus. Subjects will be randomized in a 1:1 manner to either darbepoetin alfa therapy to a target hemoglobin (Hb) of 13 g/dL or control, consisting of placebo for Hb > or =9 g/dL or darbepoetin alfa for Hb <9> or =9 g/dL. TREAT is event-driven and has a composite primary end point comprising time to mortality and nonfatal cardiovascular events, including myocardial infarction, myocardial ischemia, stroke, and heart failure. TREAT will provide data that are critical to evolution of the management of cardiovascular risk in this high-risk population.

This was the last nail in the coffin for use of ESAs to normalize hemoglobin in pre-dialysis CKD. In the years since CHOIR and CREATE one of my partners kept holding out hope for TREAT. He mentioned that TREAT made it through its interim safety monitoring without being stopped so it was unlikely to show the same detrimental findings found in CHOIR.
This data is just preliminary as it was published to satisfy financial requirements. The official results will likely be presented at Renal Week.
Posted on

EKGs that will soil your shorts

A long time dialysis patient of ours came to the ED yesterday with the chief complaint of “weakness.”

She had not missed any dialysis in the last week. She had gone to the farmer’s market on Saturday (2 days prior to admission) and had purchased some melon. She ate two melons on Saturday and a third on Monday morning. Additionally, she had potatoes on Saturday night and Sunday morning.
On arrival to the ED this was her initial EKG (click on the image for a larger picture):

The potassium was still pending at this time and no action was taken on those peaked Ts and widened QRS.
Fourteen minutes later the EKG deteriorates to a terrifying sinusoidal pattern:

Potassium was still pending but based on the EKG and history of end-stage renal disease she was given two grams of calcium chloride. The CaCl2 was given via a peripheral line. Calcium chloride should be given only via a central line due to the devastating consequences of extravasation of calcium chloride. However, calcium chloride provides three times the calcium as calcium gluconate and is more effective at squashing hyperkalemic arrhythmias. I aplaud this boldness, as it looks like this patient is about to arrest.
The calcium worked great. A minute later things cool down:
Around this time the potassium came back at 9.4 mmol/L. The patient was then given 4 units of insulin. The low dose is typical of our ED as they tend to be skittish about giving 10 units of insulin to ESRD patients due to concern over symptomatic hypoglycemia. They chased the insulin with an amp of D50 and sixty grams of Kayexalate. The glucose was 84 mg/dL prior to the insulin and D50.
Eighteen minutes later the QRS is down to 128 msec from 168 on the initial EKG:

The patient then went for dialysis for 3.5 hours. Two hours with a zero potassium bath and 90 minutes on a one potassium bath. The potassium the next day was 5.5 mmol/L.

Posted on

Delta anion gap. Not as good as we think it is.

One of the concepts that is regularly taught in the evaluation of acid-base status is determining if there are multiple acid base disorders by evaluating the ratio of the delta anion gap/delta bicarbonate.

I teach this concept as determining what the bicarbonae would be in the absence of or prior to the anion gap.

The concept comes from the idea that for every mEq of bicarbonate that is consumed by the strong acid (other anion) the anion gap should rise by one. So if the bicarb is 16, a delta of 8, we would expect an anion gap of 20, a normal anion gap of 12 plus the delta bicarbonate of 8. This is a ∆AG/∆Bicarb of one.

If the patient had a pre-existing metabolic alkalosis with a bicarbonate of 30, then the patient would have a bicarbonate of 22 and an anion gap of 20. This would give ∆AG/∆Bicarb of 8/2 or 4.
If the patient had a pre-existing metabolic acidosis (non-anion gap) with a bicarbonate of 16, then the patient would have a bicarbonate of 8 and an anion gap of 20. This would give ∆AG/∆Bicarb of 8/16 or 0.5.
Concurrent metabolic alkalosis leads to ratios over 1 and preexisting metabolic acidosis (non-anion gap) yield a ratio below 1.
I had always been suspicious of this because the assumption of the one for one change in anion gap and bicarbonate. This didn’t seem to be very biologic. Turns out my suspicion was justified as numerous studies (Androgue, Elisaf) have shown that the ratio does not hold up.
In this paper by Paulson et al they found:
[Some authors] suggested that mixed disturbances should be considered if the ratio is less than 0.8 or greater than 1.2. Paulson, applying this rule to a group of normal control subjects and patients with simple metabolic acidosis, noted that the formula erroneously categorized 56% [specificity of 44%] of this group as mixed disturbances. Use of the 95% confidence interval of ±8 mEq/L increased the specificity to 97% but with a poor sensitivity of only 27%.
That’s terrible. Why torture the brains of medical students with this type of worthlessness.
Good review here.