Anion Gap HAGMA LAGMA and NAGMA !!!

• Blood has a lot of Cations
• Blood has a lot of Anions

Total charge of Anions = Total Charge of Cations

So

Na + K + Unmeasured Cations = HCO3 + Cl + unmeasured Anions
Rearranging
Na + K - (HCO3 + Cl) = Unmeasured Anions - Unmeasured Cations
Anion Gap = Unmeasured Anions - Unmeasured Cations

Anion Gap = (Na + K) - (HCO3 + Cl)

Note that some books ignore the value of Calcium and calculate Anion Gap as Na - (HCO3+Cl)

• Unmeasured Anions: Means all anions other than HCO3 and Cl ----> lactate, phosphate, ketoacids , Albumin, Ethylene Glycol etc
• Unmeasured Cations: Means Ca, Lithium, Globulin

So
Anion Gap is Increased in

• Conditions with Increased Unmeasured Anions
1. Diabetic Ketoacidosis
2. Uremia
3. Lactic Acidosis
• Conditions with Decreased Unmeasured Cations
1. Hypocalcemia

Anion Gap is decreased in

• Conditions with Decreased Unmeasured Anions
1. Hypoalbuminaemia (theoritically)
• Conditions with Increased Unmeasured Cations
1. Increase in Globulin (multiple Myeloma)
2. Lithium Toxicity
• 
  

Easy way to solve MCQs

1. Check what is decreased / Increased

If that is Na / K / HCO3 / Cl it is Normal Anion Gap Metabolic Acidosis (also called NAGMA). The matter is settled. No doubt about that. Vomitting, Diarrhoea, Renal Tubular Acidosis etc come here

2. If there is an increase in Unmeasured Anions (lactate etc)
It is High Anion Gap Metabolic Acidosis (HAGMA)

3. If there is a decrease in Unmeasured Cations (Globulin etc)
It is High Anion Gap Metabolic Acidosis (HAGMA)

4. If there is an increase in Unmeasured Cations (lactate etc)
It is Low Anion Gap Metabolic Acidosis (LAGMA)

5. If there is a decrease in Unmeasured Anions
It is Low Anion Gap Metabolic Acidosis (LAGMA)

Any doubts !!!
Post in the comments section