Question

A young patient presented with muscle spasms, numbness in hands and feet, seizures and difficulty in breathing due to laryngospasm. His blood picture showed electrolyte imbalance. What is the cause for these manifestations in the patient?

• A. Respiratory Acidosis
• B. Respiratory Alkalosis
• C. Metabolic Acidosis
• D. Metabolic Alkalosis

Hint:

Think about how alkalosis affects the binding of calcium to albumin and thereby reduces free ionized calcium levels.

Answer 1

The Correct Option is B

Step 1: Identify the clinical features.
The patient has muscle spasms (tetany), numbness/paresthesias in extremities, seizures, and laryngospasm. These are all classic signs of hypocalcemia (specifically, reduced ionized/free calcium).

Step 2: Understand the determinants of free calcium.
Total serum calcium exists in two forms:
- Free (ionized) calcium -- physiologically active
- Protein-bound calcium (mainly to albumin) -- physiologically inactive

Two major factors control the free:bound ratio:
1. Albumin level
2. Blood pH

Step 3: Explain how alkalosis causes hypocalcemia.
In alkalosis, H⁺ ion concentration decreases. Albumin has negatively charged binding sites that normally bind both H⁺ and Ca²⁺. When H⁺ decreases (alkalosis), more albumin binding sites become available, and albumin preferentially binds more Ca²⁺. This reduces free (ionized) calcium levels, causing hypocalcemic tetany even though total calcium may remain normal.

Step 4: Identify the type of alkalosis.
The scenario describes laryngospasm causing difficulty breathing -- hyperventilation or acute respiratory change. Respiratory Alkalosis (due to hyperventilation) leads to acute decrease in blood CO₂, raising pH. This is the most common acute cause of hypocalcemic tetany via the alkalosis mechanism.

Conclusion: Respiratory Alkalosis is the cause.