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Parathyroid Gland and Dysfunction Cheat Sheet by

Hyperparathyroid, Hypoparathyroid

Anat­omy

4 total
Posterior aspect of thyroid gland
Produce and release PTH
iCal determines level of PTH secretion in body indire­ctly. Decreased Ca+ = increased PTH
PTH causes bone resorp­tion, kidney absorption and GI absorption of Ca+
Prinicipal cells secrete PTH
Half-life of PTH is 4-5 minutes
Alkalosis = decreased Ca+

Calcium

50% bound to albumin
40-45% free/i­onized
5-10% bound/­uni­onized
ionized levels are regulated and affected by pH and temper­ature
low pH (acidotic) = increased ionized Ca+
high pH (alkal­osis) = decreased ionized Ca+
Normal iCal = 4.4-5.4­mg/dL
Normal total calcium = 8.9-10.1mg/dL
Small changes in iCal leads to large changes in PTH secretion

Hyperc­alcemia Lab Values and Treatment

Normal serum Ca+ levels = 8.9-10.1mg/dL
Normal iCal = 4.75-5.7m­g/dL; 1.19-1.33­mmol/L
Mild = <3m­mol/L; 12mg/dL
hydration
Moderate to severe = 3.2-3.7 mmol/L; 13-15 mg/dL
NS and lasix
Other treatments
Ethacrynic acid - Na+/Ca+ diuresis
Biphos­pho­nates - inhibit bone resorption
Calcitonin - hormone to oppose PTH (decrease Ca+)

Hypoca­lcemia

Airway
Neurom­uscular & CNS
ECG
Recurrent laryngeal nerve damage. Unilateral (hoars­eness) Bilateral (stridor, obstru­ction)
Muscle cramps
negative inotropy
Bleeding - tracheal compre­ssion and edema
Chovstek's sign and Trouss­eau's Sign
prolonged QT
Hypoca­lcemic tetany - laryng­ospasm
Parast­hesias
 
Psychosis
 
Seizures
 

Hype­rpa­rat­hyr­oid­ism

HYPERC­ALCEMIA
Hyperc­alemia = >10.4 mg/dL
Primary - most common - due to malignancy or parath­yroid malfun­ction. 30-40 year olds. Single gland is usually benign - 80% preval­ence. Secondary - 15% - Hereditary and associated with MEN1 and MEN2A.
Signs and Symptoms: Renal - Ca+ deposits with recurrent stones. Skeletal - pathologic fractures, skeletal demine­ral­iza­tion. CNS - confusion, depres­sion. Neurom­uscular - weakness, fatigue. GI - nausea, vomiting, consti­pation, PUD, anorexia. Cardiac - prolonged PR, short QT, HTN and Osborne J waves.
Diagnosis: PTH assay with Ca+ level. Will show increased levels of PTH and hyperc­alc­emia.
Treatment: Mithra­mycin - inhibits osteoc­lasts, respir­atory alkalosis, Calcitonin (stimu­lates osteob­lasts; inhibits osteoc­lasts. i.e. Ca + is removed from the blood and used to build bone)
Most common cause of hyperc­alcemia is cancer. 25-50% of the time it is breast cancer
Anesthetic Consid­era­tions: Pts will be sensitive to succin­ylc­holine and antagonize non-de­pol­arizing NMBs

Surgical consid­era­tions

Arms will be tucked - IV access
NIM endotr­acheal tube to access nerve integrity
Consider a deep extubation
Intraop serum PTH. PTH levels should drop 20 minutes after removal
Post-op hypoca­lcemia
 

Hypopa­rat­hyr­oidism

HYPOCA­LCEMIA, HYPOMA­GNE­SEMIA and HYPERP­HOS­PHA­TEMIA
Absence of deficiency of PTH secretion or resistance of peripheral tissues to PTH
Cause: Iatrog­encic (i.e. inadve­rtent removal during thyroid surgery)
Signs and Symptoms: neuronal irrita­bility, muscle spasms, tetany, seizures, fatigue, stridor, apnea, CHF, hypote­nsion, prolonged QT, decreased response to beta agonists, fatigue, Chvostek's sign, Trouss­eau's sign and mental status changes
Treatment: electr­olyte replac­ement, avoid respir­atory alkalosis (decreases Ca+ further), phosphate binders (Seval­amir). Severe hypoca­lcemia: 10-20 mL (90mg; 0.46mEq/L) of 10% Calcium Gluconate or 3-5 mL (270mg; 1.36 mEq) of Calcium Chloride followed by 1-2mg/­kg/hr or Calcium infusion. Calcium is incomp­atible with sodium bicarb­onate
Anesthetic Manage­ment: be mindful that laryng­ospasm can occur, seizures, prolonged QT (zofran)
       
 

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