Sunday, August 31, 2008

Mnemonic for NON-Anion Gap Metabolic Acidosis

As I've mentioned previously on this blog, the "MUDPALES" mnemonic for anion gap metabolic acidosis is one of the most successful medical mnemonic's of all time.

A less successful (and admittedly less useful) mnemonic exists for non-anion gap metabolic acidoses (NAGMA), which I learned as a resident. It's "HARDUP", which stands for the following:

H = hyperalimentation (e.g., starting TPN).
A = acetazolamide use.
R = renal tubular acidosis (Type I = distal; Type II = proximal; Type IV = hyporeninemic hypoaldosteronism.
D = diarrhea
U = uretosigmoid fistula (because the colon will waste bicarbonate).
P = pancreatic fistula (because of alkali loss--the pancreas secretes a bicarbonate-rich fluid).

Practically speaking however, the two main causes you really have to remember for NAGMA are DIARRHEA or RENAL TUBULAR ACIDOSIS, which 90% of the time you can distinguish between based on the history alone. Another way to think about the differential diagnosis of NAGMA is to ask whether or not there is GI LOSS or RENAL LOSS of bicarbonate. If the history does not provide an obvious explanation, one can distinguish between GI versus renal bicarbonate losses by determining the urine anion gap (urine AG = urine Na + urine K - urine Cl), where a positive value indicates renal bicarbonate loss whereas a largely negative value indicates extra-renal bicarbonate loss.


Anonymous said...'s MNEMONIC!

Anonymous said...

What about Addison's? I thought that could cause NAGMA as the lack of cortisol/aldosterone leads to renal sodium wasting but retention of H+ and K+ ions. I can't remember the exact transporters or ion channels involved because I'm not a renal physician (but I did know at one time!). The mnemonic I use is for NAGMA is "DARA" - Diarrhoea (or variants thereof, eg. fistulae), Acetazolamide, Renal tubular acidosis, Addison's. Any thoughts?

Anonymous said...

I still like "HARDUP". When I was learning different languages as a kid... the dirty words and phrases always "came quick" and stuck!

Anonymous said...

RTA (type 3) accounts for aldo

Anonymous said...

What about Aggresive Saline recus as a cause? You could add an "S" on the end to make HARDUPS (Saline recus)?

Dr. Helbert Rondon said...

My mnemonics for NAGMA is FORD
RTA/Renal failure

Anonymous said...

thanks for posting..

Anonymous said...

what about aggressive fluid resuscitation w/ NS, its anoher cause of NAGPMA

Anonymous said...

What about DURHAM?

Anonymous said...

as a non-renal fellow from durham--thanks for posting!!

Anonymous said...

Aggressive saline = Hyperchloremia

Zaf said...

Mnemonic I use for NAGMA is "ABCD"
- Addisons
- Bicarb loss (Renal or GI)
- Chloride excess (eg normal saline)
- Drugs eg acetazolamide
It seems to cover all the options people have mentioned previously...