My fellow remembers the urinary anion gap by saying:
NeGUTive
So a negative urinary anion gap is due to gut losses as opposed to an RTA.
Cute.
Highest creatinine I have seen in acute kidney injury
We had a patient earlier this month who presented with a creatinine that was 20 mg/dL on admission and rose to 22 on the repeat. That is the highest creatinine I have ever seen in a patient with acute kidney injury. I have a seen two patients with advanced CKD with creatinines in the mid to high thirties. (34 and 37 mg/dL).
When my fellow described the patient I was sure this was going to be CKD until she mentioned, rather triumphantly, that when she examined the patient she palpated a large bladder. She had a Foley placed and the patient voided 1300 mL of urine in the next hour.
Obstructive uropathy in a woman is cervical cancer until proven otherwise. Sure enough, a subsequent CT scan of the pelvis revealed a pelvic mass which was diagnosed as cervical cancer.
The patient was discharged with a creatinine of 1.9 mg/dL.
A few aspects of the case were interesting and surprising:
- Obstructive uropathy causes an electrogenic type 1 RTA (hyperkalemic type 1 RTA as opposed to the hypokalemic classic type 1 RTA). Because of the RTA, these patients often have hyperkalemia out of proportion to the degree of renal failure. She was not hyperkalemic and presented with a potassium of 4.6 mEq/L.
- The patient had a pH of 7.2, bicarbonate of 4 and a pCO2 of 8, giving her a metabolic acidosis and a respiratory alkalosis (predicted pCO2 by Winter’s formula is 14±2). I had been taught that patients cannot blow off CO2 below 14 mmHG. I guess she had super lungs. As best we could tell, the respiratory alkalosis was due to anxiety and resolved the following day.
- My fellow wanted to give bicarbonate for the metabolic acidosis, but I did not. The pH of 7.2 is fine and the patient was hemodynamically stable. Her total calcium was 4.6 and her phosphorous was 10. I was worried that giving bicarbonate would correct the acidosis which at the time was essential to prevent the hypocalcemia from causing tetany or worse. The acidosis shifts bound inactive calcium to the unbound and active ionized form.
GOLDMARK: the real story.
I co-wrote a fluid and electrolyte book while in residency. During the final push to finish the book we enlisted some friends to help with proof reading and editing in a week-long proof-reading orgy. Joel Smith, a wayward cellular molecular biologist who ended up a lawyer asked, “Is there something special about the mnemonic for anion-gap metabolic acidosis, MUDSLEEPS? Is the word important? Or just the letters?”
I explained that it was a standard mnemonic along with its cousin MULEPILES. He said that’s stupid and that we should make-up our own mnemonic. Five minutes later he came up with PLUMSEEDS, an exact anagram of mudsleeps, and we used that in the book. I thought it would be a marker of who used our book to learn acid-base, if they used plumseeds they were our’s otherwise, not so much.
9 years have passed and I have yet to hear anyone use PLUMSEEDS.
FAIL
This past September, my partner Susan Steigerwalt, put a letter on my desk she photocopied (she’s old school) from Lancet. The letter described a new mnemonic for the differential of anion-gap metabolic acidosis: GOLDMARK. This reworked mnemonic had more going for it than an ego test, it was a complete reworking of the old and busted mnemonic for new hotness.
I blogged about GOLDMARK a few months ago and received an e-mail from the lead author. I have since e-mailed all three authors. Here’s their story.
In May of 2008, Josh Emmett a second-year medical student at University of Texas Southwestern was having dinner with his dad Dr. Michael Emmett, Chief of Nephrology at Baylor University in Dallas. Dr. Emmett was telling Josh that he and a fellow were frustrated with MUDSLEEPS/MULEPILES/KUSMALE because of its obvious shortcomings: paraldehyde? No one uses that. DKA, Starvation and Ethanol, all of those cause ketoacidosis. Isoniazid/iron as causes of lactic acidosis? The next time I see that will be the first time I see that. Plus no D-lactic acid, no oxoproline, an issue that must have particularly rankled Dr. Emmett as he was an author on the definitive article on the subject.
Josh, looking for a distraction from his studies volunteered to help craft a new mnemonic. Dr. Emmett and a third-year IM resident, Ankit Mehta (who has subsequentky become a nephrology fellow with Dr. Emmett), came up with the letters they would use and the synonyms for different diseases:
Uremia could be U, R or K (Renal, Kidney)
Ethylene glycol could be A, E or G (Antifreeze, Glycol)
Oxoproline could be O or P (Pyroglutamic acid)
Aspirin could A or S (Salicylate)
Ketoacidosis could be K or D (Diabetes, though that is not nearly as good as ketoacidosis because there are other causes of ketosis besides DKA)
With that list in hand Josh hit the internets and plugged the letters into some mnemonic generating websites and came up with:
- ELK DUMP
- SUDOKKU
- PULSE something
- MOPED
After a few days of vetting the possibilities they settled on GOLDMARK.
GOLDMARK has become my standard AGMA mnemonic. Bye bye PLUMSEEDS.
- Glycol: ethylene glycol
- Oxoproline: Pyroglutamic acid
- L-lactic acid
- D-lactic acid
- Methanol
- Aspirin
- Renal failure
- Ketoacidosis
UPDATE: Dr. Ankit Mehta sent me some notes from when they were trying to find mnemonic:
Hi Dr.Topf,
I was cleaning my desk over the weekend and found some papers on which i was scratching some other mnemonics for agma:
- MOLDS REEK
- DUKES MOLE
- LU SMOKED
- DUSK MOLE
- SMOK(ing) ALE
- LAME SUDOK(u).
As you see none of them are as good as GOLD MARK. Also, some are a stretch of imagination!
hope this helps,
Ankit.
I weep that I won’t ever get to pimp medical students on the meaning of SMOKing ALE
ABG questions and answers
I have been editing our consult month syllabus adding the links for the study materials as we go.
Today we fell off the syllabus. The acid-base lecture on Wednesday revealed a chasm of ignorance. We need to really pound on the basics. So today, instead of doing a Powerpoint style lecture on non-anion gap metabolic acidosis, we sat in a conference room with a couple of calculators and pounded through 23 ABG problems.
While we were going through the questions, part of me wanted some tunes. Just saw Slum Dog last weekend.
Internal Medicine Board Review: Fluids, Electrolytes and Acid Base
The chief resident at Providence asked me to do a board review class for the third-years. They have small sessions weekly (?) in the physician lounge. This afternoon we went over fluids, electrolytes and acid-base. We did the first 14 questions. Seems like it went pretty well.
Testing a new webservice: Zoho
Here is my worksheet I used to create the problems for the acid-base hand out: