ELECTROLYTE RELATIONSHIPS
RN-NURSE • NCLEX High-Yield Review
KEY ELECTROLYTE RELATIONSHIPS
Sodium / Potassium — Inverse ↑ Na⁺ = ↓ K⁺
Calcium / Phosphate — Inverse ↑ Ca²⁺ = ↓ PO₄³⁻
Calcium / Vitamin D — Similar ↑ Ca²⁺ = ↑ Vitamin D
Magnesium / Calcium — Similar ↑ Mg²⁺ = ↑ Ca²⁺
Magnesium / Potassium — Similar ↑ Mg²⁺ = ↑ K⁺
Magnesium / Phosphate — Inverse ↓ Mg²⁺ = ↑ PO₄³⁻
- Inverse relationship: Electrolytes move in opposite directions (think fraternal twins).
- Similar relationship: Electrolytes move in the same direction (think identical twins).
- Vitamin D helps calcium absorption — it is the “big sister” to calcium.
- Low magnesium often causes refractory hypokalemia.
- NCLEX tip: Always check Mg²⁺ when K⁺ or Ca²⁺ won’t correct.
Electrolyte Relationships Quiz
1. Which electrolyte has an inverse relationship with calcium?
2. Low potassium that does not correct is often caused by low:
3. Vitamin D has which relationship with calcium?
