Tetany: quantitative interrelationships between calcium and alkalosis

Area of Science:

• Physiology
• Neurology
• Endocrinology

Background:

• Tetany is a neuromuscular disorder associated with hypocalcemia and/or alkalosis.
• The interplay between calcium levels and acid-base balance in tetany development is complex.
• Previous research has not fully elucidated the independent roles of hypocalcemia and alkalosis in tetany.

Purpose of the Study:

• To investigate the interrelationship of calcium and acid-base balance in inducing tetany.
• To determine the role of the central nervous system in tetany.
• To examine the influence of the rate of hypocalcemia development on tetany.

Main Methods:

• Inducing hypocalcemia and/or alkalosis in dogs using hyperventilation or ethylene glycol-bis(beta-amino ethyl ether) N, N'-tetraacetate infusion.
• Performing thyroparathyroidectomy to induce slowly evolving hypocalcemia.
• Monitoring serum calcium ion concentration, arterial pH, CO2 tension, and cerebrospinal fluid (CSF) calcium ion content.

Main Results:

• Hypocalcemia combined with hypocapnic alkalosis consistently produced tetany.
• Slowly evolving hypocalcemia followed by hypocapnic alkalosis also induced tetany.
• Tetany was not correlated with cerebrospinal fluid (CSF) calcium ion concentration.
• An identical relationship between serum calcium, pH, and CO2 was observed regardless of the rate of hypocalcemia development.

Conclusions:

• Hypocalcemia and alkalosis are essential coparticipants in tetany development.
• The rate of hypocalcemia development does not influence tetany.
• Cerebrospinal fluid (CSF) calcium ion concentration is not a determinant of tetany.
• Alkalosis plays a critical role in tetany associated with hypoparathyroidism.