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The difference between acidosis and acidaemia, acidosis is the process that causes the acidaemia.

Stewarts Theory

The advantage of stewarts is that it gives a quantitive approach.

Strong Ions - Difference between the positives and the negatives

H+ and HCO are dependent factors, that depend on the independent factors (the strong ions)

Strong Ion Gap is essentially the anion gap.

Strong Ion Difference, is simplified to Sodium minus Chloride

Stewarts theory is that we always maintain neutrality in the blood that trhere's always neutrality between positive and negative ions.

Remember that albumin is a weak acid (its one of the unmeasured anions)

Anion Gap

Na + K - Cl + HCO3 ; Measured Cations - Measured Anions

The idea is the gap is only the measured positives and negatives. So the gap represents the unmeasured ions.

Unmeasured Cations

Magnesium Calcium Paraprotein Lithium

Unmeasured Anions

Albumin - How do you calculate this - For every 10 of albumin, add 2.5 Phosphate Lactate Ketones Toxins Sulfate Phosphate

Raised Anion Gap

MUDPILES

GOLDMARK

  • Glycols
  • Oxyprolene
  • Lactate (LLactate, there is also DLactate)
  • Methanol
  • Aspirin
  • Renal Failure
  • Ketones

KULT/LTKR

  • Ketones
  • Urea
  • Lactate
  • Toxins

Osmolar Gap

Measured Osmolarity - Calculated Osmolarity

If theres a gap, it means theres sometthing else in the blood that isn

Ethanol/3.7 to add it to the osmolar gap

Calculated Osmolarity: 2x(NA) + Ur + Glu + (Ethanol/3.7)

  • Methanol - Breaking down to formic acid (by alcohol dehydrogenase) (that won't act osmolality)
  • Ethanol - Breaking down to acetyl co-a (by alcohol dehydrogenase) (that won't act osmolality)
  • Ethylene Glycol - Breaking down to glycolic acid, then oxalic acid (by alcohol dehydrogenase) (they won't act osmolality)
  • Ketosis (Acetone)
  • Lactic Acidosis

As those guys break down you wont see them any more in your tests, and they won't act in osmolality so no osmolar gap. But they break down in acids so they'll affect your anion gap.

So if you're over 30, pretty much only toxic alcohols can cause that

If you're under 10, it's almost certainly not toxic alcohols

Methanol

Looks drunk Visual disturbance (Snowstorm) Seizures Lactic acidosis

Ethylene Glycol

Binds to calcium It's the glycolic acid that breaks the gas machine

Alcohol Ketoacidosis

No glycogen stores for the alcoholic, no longer drinking as acutely unwell, breaks down fats when unwell so produces ketones

Low sugar Ketones

Positive blood ketones, negative urine ketones - think alcoholic ketoacidosis Properly acidotic

Pyroglutamic Acid (Oxyprolene)

You're on fluclox (which blocks break down of pyrotamic acid)

Normal Anion Gap

ABCD

Addisons Bicarb Loss Chloride Drugs (Acetozolamide)

Beware a high anion gap metabolic acidosis masquerading as a normal gap metabolic acidosis

Investigations

Use history

Do cortisol for addisons

For renal bit - Is it cos kidneys are the issue or because it's something else

You can look at a urinary anion gap

Urine Na + Urine K - Urine Chloride

Chloride is excreted with ammonium - that's important somehow...

Combined Metabolic Disorders

This is where you have two issues almost balancing each other out, or respiratory compensation

You use a Delta Ratio to work it out.

This goes back to electrochemical neutrality.

>2 = mixed hagma and metabolic alkalosis

<1 = mixed hagma and normal agma