: How does hyperventilation cause paresthesia and tetany? As per this previous answer to "Why do I feel small stings all over my body in stress?", hyperventilation is known to cause tingling, numbness, or muscle spasms

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The two proposed mechanisms for paresthesia/tetany secondary to hyperventilation are cerebral vasoconstriction and electrolyte imbalance.
Cerebral vasoconstriction: Cerebral blood flow decreases in a linear relationship to decreased PaCO2 (partial pressure of carbon dioxide). Thus, hyperventilation -> decreased PaCO2 -> decreased cerebral blood flow -> neurologic manifestations in distal extremities.
Electrolyte imbalance: Since CO2/HCO3- is a major pH buffer in our blood, hyperventilating removes H+ from our blood, leading to alkalosis. Serum H+ normally prevents calcium from binding to albumin in a competitive manner. Decreased serum H+ -> increased calcium binding to albumin -> local hypocalcemia, which can explain the paresthesia/tetany in distal extremities. Hypophosphatemia is also found in hyperventilation, which can contribute to tetany.
Source:
Schwartzstein, RM. et al. Hyperventilation syndrome in adults. In: UpToDate (Accessed on September 14, 2020 from www.uptodate.com/contents/hyperventilation-syndrome-in-adults)