Tetany

Template:Search infobox Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

## Contents

* 1 Overview
* 2 Mechanism
* 3 Causes
* 4 Diagnosis
* 5 Differential Diagnosis
* 6 References
* 7 External links

## Overview

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Tetany is a medical sign, the involuntary contraction of muscles, caused by diseases and other conditions that increase the action potential frequency. The muscle cramps caused by the disease tetanus are due to a blocking of the inhibition to the neurons that supply muscles and are not classified as tetany. Tetany has two meanings, though both are related to the muscular system.

* Tetany (action potential summation)
* Tetany (medical sign)

The terms "tetany" and "tetanus" are distinct.

Tetany must be distinguished from the following:

* Muscle twitches
* Cramps
* Carpopedal spasm

## Mechanism

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When the membrane potential is upset, for instance by low levels of ions (such as calcium) in the blood (hypocalcaemia), neurons will depolarize too easily. In the case of hypocalcaemia, calcium ions are drawn away from their association with the voltage-gated sodium channels thus sensitising them. The upset to membrane potential is therefore caused by an influx of sodium to the cell, not directly by the hypocalcaemia. As a result, too many action potentials are sent to muscles causing spasm.

## Causes

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The usual cause of tetany is lack of calcium, but excess of phosphate (high phosphate-to-calcium ratio) can also trigger the spasms. Milk-and-alkali tetany is an example of this imbalance.

Underfunction of the parathyroid gland can lead to tetany.

Low levels of carbon dioxide causes tetany by altering the albumin binding of calcium such that the ionised (physiologically influencing) fraction of calcium is reduced; the most common reason for low carbon dioxide levels is hyperventilation.

## Diagnosis

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The nineteenth-century clinician Professor Armand Trousseau devised the trick of occluding the brachial artery by squeezing to trigger the cramps in the fingers (Trousseau sign).

## Differential Diagnosis

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In alphabetical order In alphabetical order. [1] [2]

* Addisonian crisis
* After multiple transfusions
* Alcoholism
* Brain injury
* Burns
* Cirrhosis
* Conn's Syndrome
* Diabetic precoma
* Drugs such as Oxcarbazepine
* Hemolytic crisis
* Hypercalcemia
* Hyperkalemic tetany
* Hyperventilation
* Hypocalcemia
* Hypoparathyroidism
* Intoxication
* Lack of Vitamin D
* Lactation
* Long term diuretic medication
* Malabsorbtion syndrome
* Neuropathy
* Pancreatitis
* Pregnancy
* Pseudohypoparathyroidism
* Recurring vomiting
* Renal failure
* Toxins
* Uncontrolled intravenous potassium supply
* Zollinger-Ellison Syndrome

## References

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1. ↑ Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:77 ISBN 1591032016
2. ↑ Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:68 ISBN 140510368X

## External links

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* Bartleby

* v
* t
* e

Symptoms and signs: circulatory (R00–R03, 785)

Cardiovascular|

Template:Navbox subgroup

Myeloid/blood|

Template:Navbox subgroup

* v
* t
* e

Symptoms and signs: respiratory system (R04–R07, 786)

Hemorrhage|

* Epistaxis
* Hemoptysis

Abnormalities
of breathing|

Respiratory sounds

Stridor
Wheeze
Crackles
Rhonchi
Hamman's sign

Apnea
Dyspnea
Hyperventilation/Hypoventilation
Hyperpnea/Tachypnea/Hypopnea/Bradypnea
Orthopnea/Platypnea
Trepopnea

Biot's respiration
Cheyne-Stokes respiration
Kussmaul breathing

Hiccup
Mouth breathing/Snoring
Breath-holding

Other|

* Asphyxia
* Cough
* Pleurisy
* Sputum

* Respiratory arrest
* Hypercapnia/Hypocapnia

* Pectoriloquy: Whispered pectoriloquy
* Egophony
* Bronchophony

* Pleural friction rub

* Fremitus

* Silhouette sign

Chest, general|

* Chest pain
* Precordial catch syndrome

* v
* t
* e

Symptoms and signs: digestive system and abdomen (R10–R19, 787,789)

GI tract|

Template:Navbox subgroup

Accessory|

Hepatosplenomegaly/Hepatomegaly
Jaundice

Abdominopelvic|

Ascites

Abdominal – general|

Abdominal pain (Acute abdomen, Colic, Baby colic)

Splenomegaly

Abdominal guarding * Abdominal mass * Rebound tenderness

Shifting dullness * Bulging flanks * Puddle sign * Fluid wave test

Template:Skin and subcutaneous tissue symptoms and signs Template:Nervous and musculoskeletal system symptoms and signs Template:Urinary system symptoms and signs Template:Cognition, perception, emotional state and behaviour symptoms and signs Template:Speech and voice symptoms and signs Template:General symptoms and signs

* v
* t
* e

Symptoms and signs: Symptoms concerning nutrition, metabolism and development (R62–R64, 783)

Ingestion/Weight|

decrease: Anorexia • Weight loss/Cachexia/Underweight

increase: Polyphagia • Polydipsia • Orexigenia • Weight gain

Growth|

Delayed milestone • Failure to thrive • Short stature (e.g., Idiopathic)

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