4.14 G) Acid Base Disorders Osmolar Gap

Front 1

Serum Osmolality range

Back 1

270-290 mmol/L

Front 2

Osmolar Gap Equation

Back 2

Calculated - Measured
Indicates the QUANTITY of OSMOTICALLY ACTIVE substances in serum -that are NOT MEASURED by standard electrolyte tests
= ( 2 x Na+) + Urea + Glucose + ethanol

Front 3

Non measured osmotically Active Substances

Back 3

1. Alcohols
- Toxic alcohols {methanol/ethylene glycol/propylene glycol}
- IV mannitol
- sorbitol
2. Lithium
3. Calcium
4. Other : [ Proteins / Lipids / Acetone/formaldehyde]

Front 4

Delta Gap?

Back 4

= Delta Ratio
= Increase in Anion Gap / Decrease in HCO3
normal ratio = 1

Front 5

Delta Gap Interpretations ?

Back 5

< 0.4 = Hyperchloraemic NAGMA

0.4-0.8 = HAGMA + NAGMA

1-2 = uncomplicated HAGMA {lactic/DKA}

> 2 = pre-existing : 1. metabolic alkalosis
2. Respiratory acidosis

Front 6

Urea: Creatinine ratio
5 facts

Back 6

1. Little evidence for Clinical use
2. Used to differentiate Causes of renal Failure {Pre-renal vs renal vs post-renal}
3. Urea mmol/L / Creatinine mmol/L
4. Normal approx 100
5. > 100 = pre-renal RF

Front 7

Causes of Elevated Urea:Creatinine ratio?

Back 7

1. Sepsis
2. GIT Blood [ ratio >200 90% sens.]
3. Dehydration
4. CCF
5. Steroids