Thread by @medrants

1/ #UncleBob on treating metabolic acidosis. First, get this article:
Sabatini, S., Kurtzman, N. (2009). Bicarbonate Therapy in Severe Metabolic Acidosis JASN 20(4), 692-695. dx.doi.org/10.1681/asn.20…

@UnremarkableLab @kidney_boy @hswapnil @CPSolvers
@uabimres @UAB_NRTC

2/ Here is the quick chalk talk.
For increased anion gap metabolic acidosis, treat the underlying cause. Do not give bicarbonate unless you have an extraordinarily low pH (debate whether this is < 7.2 or 7.1 or 7. And with DKA, NEVER.

3/ For normal gap metabolic acidosis ALWAYS give bicarbonate with a goal of ~ 22 for the bicarbonate.

How?

Estimate bicarbonate deficit = 22 - current bicarb
Multiply by bicarbonate space = TBW = 50% wt in kg (+/- 10%)

4/ Example:
We had a 70 kg man admitted with severe diarrhea and a bicarbonate of 17 (normal gap)
Therefore 22-17 = 5 * 35 liters = 175 mEq

So we chose 3 amps of sodium bicarbonate into a liter of D5/W. We'll check his bicarbonate today and then titrate

5/ With chronic metabolic acidoses like the NAGMA of CKD, once we return the bicarbonate to 22, then we need maintenance bicarbonate. If we assume that most people need to buffer ~ 1 mEq/kg of acid daily. Then titratable acid (phosphate) will usually handle around 50%

6/ Non-titratable acid (NH4+) is the problem. With CKD we often have decreased NH3 available for conversion to NH4+ in the distal tubule. I usually estimate about 20-30 mEq of bicarbonate daily to maintain our bicarbonate in the 22 range.

7/ We can either give sodium bicarbonate or sodium citrate. Use 650 mg tablets (~7.7 mEq per tablet) or 1300 mg tablets (~15.4 mEq per tablet) or baking soda (1 tsp ~ 60 mEq). So with a starting estimate of 30 mEq: 4 650s or 2 1300 or 1/2 tsp of baking soda. Then titrate

8/ If we give sodium citrate (Shohl's or bicitra) get converted to sodium bicarbonate - 1 mEq/ 1 cc - so 30 cc of sodium citrate to start.
Beware that this tastes horrible - imagine Rose's lime juice with too much salt added.

9/ Please ask questions or critique and make more clear.