Question:medium
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 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?
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Think about how alkalosis affects the binding of calcium to albumin and thereby reduces free ionized calcium levels.
Updated On: Jun 23, 2026
- Respiratory Acidosis
- Respiratory Alkalosis
- Metabolic Acidosis
- Metabolic Alkalosis
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The Correct Option is B
Solution and Explanation
Pathophysiology of Hypocalcemic Tetany in Alkalosis:
Total serum calcium = ionized (free) $Ca^{2+}$ + protein-bound $Ca^{2+}$
Albumin binds $Ca^{2+}$ competitively with $H^+$ ions. In alkalosis, $[H^+]$ falls, freeing more albumin binding sites which then sequester more $Ca^{2+}$:
\[\text{Alkalosis} \Rightarrow \downarrow [H^+] \Rightarrow \uparrow \text{albumin-Ca}^{2+} \text{ binding} \Rightarrow \downarrow \text{free } Ca^{2+}\]
This decrease in ionized $Ca^{2+}$ raises nerve membrane excitability, causing:
- Muscle spasms and tetany
- Perioral and peripheral paresthesias
- Laryngospasm
- Seizures
Respiratory Alkalosis (hyperventilation or acute laryngospasm) causes rapid $CO_2$ washout, $\uparrow$ pH, and acute hypocalcemia -- explaining all the features in this patient. Metabolic alkalosis can have a similar effect but the acute scenario and laryngospasm point to respiratory origin.
Answer: \[\boxed{\text{Respiratory Alkalosis}}\]
Total serum calcium = ionized (free) $Ca^{2+}$ + protein-bound $Ca^{2+}$
Albumin binds $Ca^{2+}$ competitively with $H^+$ ions. In alkalosis, $[H^+]$ falls, freeing more albumin binding sites which then sequester more $Ca^{2+}$:
\[\text{Alkalosis} \Rightarrow \downarrow [H^+] \Rightarrow \uparrow \text{albumin-Ca}^{2+} \text{ binding} \Rightarrow \downarrow \text{free } Ca^{2+}\]
This decrease in ionized $Ca^{2+}$ raises nerve membrane excitability, causing:
- Muscle spasms and tetany
- Perioral and peripheral paresthesias
- Laryngospasm
- Seizures
Respiratory Alkalosis (hyperventilation or acute laryngospasm) causes rapid $CO_2$ washout, $\uparrow$ pH, and acute hypocalcemia -- explaining all the features in this patient. Metabolic alkalosis can have a similar effect but the acute scenario and laryngospasm point to respiratory origin.
Answer: \[\boxed{\text{Respiratory Alkalosis}}\]
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