Calculate the anion gap from the following information: Na+ = 137mmol/L K+ = 4 mmol/L Cl- = 110 mmol/L HCO3 = 15 mmol/L
**Question:** Calculate the anion gap from the following information: Na+ = 137mmol/L K+ = 4 mmol/L Cl- = 110 mmol/L HCO3 = 15 mmol/L
**Core Concept:** Anion gap is a measure of the difference between anions (negatively charged ions) and cations (positively charged ions) in the blood. It helps in identifying acid-base imbalances and detecting specific disorders.
**Why the Correct Answer is Right:**
The anion gap is calculated as follows:
Anion gap = Na+ + 2 x K+ + Glucose + Non-volatile Anions
Given values:
Na+ (Sodium) = 137 mmol/L
K+ (Potassium) = 4 mmol/L
Cl- (Chloride) = 110 mmol/L
HCO3- (Bicarbonate) = 15 mmol/L
Following the formula:
Anion gap = 137 + 2 x 4 + 0 (assuming glucose is at normal level, typically 4-5 mmol/L) + 110
Anion gap = 137 + 8 + 110
Anion gap = 225 mmol/L
**Why Each Wrong Option is Incorrect:**
A. This option is incorrect because it only considers Na+ and Cl- ions, neglecting the important contribution from HCO3-.
B. This option is incorrect as it only considers Na+ and K+ ions, disregarding the Cl- and HCO3- anions.
C. This option is incorrect because it only considers Na+, K+, and Cl- ions, ignoring HCO3-.
D. This option is correct, as it considers all ions (Na+, K+, Cl-, and HCO3-) and calculates the anion gap accurately.
**Core Concept:** Anion gap helps in distinguishing between different acid-base disorders and aiding in diagnosis and treatment planning.
**Why the Correct Answer is Right:**
The anion gap is increased in conditions like lactic acidosis, ketoacidosis, and some renal/hepatic disorders. In such cases, the body produces excessive anions, leading to an elevated anion gap.
**Why Each Wrong Option is Incorrect:**
A. This option is incorrect because it does not consider HCO3-, which is a significant contributor to the anion gap.
B. This option is incorrect because it only considers Na+, K+, and Cl-, ignoring HCO3-, which is a critical component of the anion gap calculation.
C. This option is incorrect because it only considers Na+, K+, and Cl-, neglecting HCO3-, which is a crucial component of the anion gap calculation.
D. This option is correct as it accurately calculates the anion gap considering all relevant ions, providing a valuable diagnostic tool for acid-base disorders.
**Clinical Pearls:**
The calculated anion gap can help differentiate between different acid-base disorders. For example