Endocrine (Altose): Thyroid and Parathyroid Hormones Flashcards Preview

Basic Science II > Endocrine (Altose): Thyroid and Parathyroid Hormones > Flashcards

Flashcards in Endocrine (Altose): Thyroid and Parathyroid Hormones Deck (40):
1

What is the hormonal pathway leading up to the release of thyroid hormones?

TRH (hypothalamus) --> TSH (anterior pituitary) --> T3/T4 bind to TBG (thyroid) --> TBG carries T3/T4 throughout the bloodstream

 

TRH: Thyroid Releashing Hormone

TSH: Thyroid Stimulating Hormone

TBG: thyroxine binding globulin

2

What is the first line screening test for thyroid dysfunction?

Why is this useful?

What values indicate hyper-, eu-, and hypo-thyroid states?

TSH levels

Iodine and T3/T4 (thyroid hormones) inhibit TRH and TSH secretion, so the level of TSH is a reflection of circulating T3/T4

 

~0-3: hyperthyroid

~3-10: euthyroid

~10-15: hypothyroid

3

What is the primary negative feedback loop involved in thyroid hormone regulation?

TRH and TSH stimulate thyroid hormone secretion

Iodine and thyroid hormone inhibit TRH and TSH secretion

4

Why are T4 levels a poor indicator of thyroid function?

T4 levels are not reliable due to extensive protein binding to TBG.

5

80% of T3 is produced by this process...

Extra-thyroidal de-iodination of T4

6

Compared to T4, T3 is ___ potent and _____ protein bound.

More, less

7

How much T3/T4 is free circulating hormone?

<0.1% of the T3 and T4 produced by the body.

8

What are some symptoms of hyperthyroidism?

Anxiety

Wt loss

Diarrhea

Weakness

Tremors

Warmth

Heat intolerance

Tachycardia

Increased pulse pressure

HF

AFib

9

What are some intrinsic causes of hyperthyroidism?

Goiters

Adenoma

Graves

Thyroiditis

10

What are some extrathyroid causes of hyperthyroidism?

Iatrogenic injury

Excess iodine

Hypothalamic tumor

Carcinoma

11

How should hyperthyroid patients be optimized?

They should be euthyroid on DOS.

This can take 6-8 weeks (NaI/KI --> PTU, methimazole)

12

In hyperthyroid pts, what meds should you avoid?

Sympathetic system stimulating meds (ketamine, pancuronium/pavulon, ephedrine, halothane)

13

Hyperthyroidism is commonly accompanied by this autoimmune disease. What is the disease and how does it effect our anesthetic plan?

Myesthenia Gravis

We need to reduce our initial NMB dose.

14

Thyroidectomies are common surgeries that hyperthyroid patients undergo.

What are some common post-op complications of thyroidectomies?

Superior and Recurrent Laryngeal Nerve damage

Hematoma

HypoPTH (leads to hypo Ca++) w/ stridor

Corneal injury (due to exophthalmos of Graves)

 

Stridor can last 24-96 hours post-op

15

What are risk factors for the occurrence of thyroid storm? (Think Sx situations and disease states)

Thyroid Storm Is Deadly Man:

Trauma

Surgery

Infection

DKA

Mental status changes

16

What diseases/intra-op malignancies do thyroid storms resemble?

Malignant Hyperthermia

Pheochromocytoma

17

What are intra-operative treatments for thyroid storm?

Beta-blockade (esp with propranolol which inhibits T4->T3 conversion)

Decadron (reduces thyroid secretion and inhibits T4->T3 conversion)

PTU/methimaxole (via NGT)

NaI/KI

IVF

Cooling

Ofirmev

18

What are absolutely contraindicated in the treatment of thyroid storm?

Any drugs that increase sympathetic output or hyperthermia

Aspirin! (can increase T3/T4 levels)

19

What are symptoms of hypothyroidism?

Depression

Lethargy

Cold intolerance

Decreased response to hypoxia/hypercapnia

Bradycardia

20

What are primary and secondary causes of hypothyroidism?

Primary:

Autoimmune diseases

Iatrogenic injury

Thyroiditis

Iodine Deficiency

 

Secondary:

Pituitary dysfunction

Hypothalamic dysfunction

 

 

21

What are the effects of decreased thyroid function on MAC?

None

22

What are some pre-op and intra-op concerns with hypothyroidism?

No real pre-op concern; pt does not have to be euthyroid unless severe

Watch out for bradycardia, etc.. ; no agents absolutely contraindicated

Consider A-line to manage CV

23

What is myxedema coma?

What is its mortality rate?

When does it occur?

What are its symptoms?

How do we treat it?

An outcome of severe hypothyroidism with a mortality rate of 25-50%

Usually occurs after stressful events (MI, infection drugs)

Symptoms: Stupor, hypoventilation, HoTN, hyponatremia

Treatment: IV thyroid replacement, steroids, warming

24

~50% of your body's serum Ca++ is bound to this protein. What is it?

What is the rest bound to?

Albumin

The other 45% are ionized free (bound to nothing)

25

What are the functions of PTH (parathyroid hormone)?

Maintain serum Ca and Mg (renal reabsorption, bone resorption as well as GI absorption which requires vit D)

Phosphate excretion (occurs renally as Ca++ is reabsorbed)

 

Note: Mg+ will tend to follow Ca++

26

What is Calcitonin?

Where does it come from?

What does it do?

It is a hormone secreted from the thyroid gland?

It inhibits PTH (wastes Ca/Mg, save phosphate)

27

Vitamin __ assists Ca++ absorption from the ______________.

D, GI tract

28

HyperPTH means a high level of this ion.

Ca++

29

What are some primary causes of hyperPTH?

Hyperplasia (too much cell growth)

MEN (multiple endocrine neoplasia) syndrome

Ectopic production (tumor)

Adenoma

30

What are some secondary causes of hyperPTH?

Hypocalcemia

Hyperphosphatemia

31

What are symptoms of hyperPTH?


Stones Bones Groans Moans:

kidney Stones (nephrolithiasis)

Bone pain

GI problems (ulcers)

Psychiatric overtones (fatigue, depression, thirst)

 

 

CV symptoms:

bradycardia, HTN, short QT, heart block

32

What are some treatments for HyperCa++?

IVF + Lasix

Calcitonin

Dialysis

Biphosphonates

33

What population of patients are especially susceptible to the negative effects of hyperPTH and should be surgically treated?

Pregnant women due to high maternal/fetal mortality

34

Unlike many other electrolytes, excessive amounts of calcium tend to be excitatory/depressive. (choose one)

Depressive

35

What are some post-op complications associated with parathryoidectomies?

Airway edema

Nerve injury

Electrolyte imbalance (Ca/Mg/Phos)

Hungry bone syndrome (bones absorb Ca++ at high rates in response to surgery)

36

What are some causes of hypoparathyroidism?

What electrolyte imbalance does it cause?

Causes:

Removal of PTH glands

Neck trauma

Severe hypoMg (Ca++ and Mg+ follow each other)

Malignancies

 

Causes HypoCa++

37

What are some signs of HypoCa++?

Spasms

Seizures

Latent tetany (Trousseau)

 

Parasthesias

Fatigue

Stridor

 

CHF

HoTN

Long QT

38

Bonus. What is another name for Versed?

Midazolam. Good job, you're awesome.

39

Most common cause of hyperthyroidism is..

Graves disease

40

How do you distinguish between thyroid storm and MH?

Hyperventilation of pt will not decrease PaCO2 in MH but will decrease in thyroid storm.

(Gauge through ABGs)