Case 5: Palpitations Flashcards Preview

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Flashcards in Case 5: Palpitations Deck (57):
1

Hyperthyroidism pathophysiology

Increased T3/T4 that causes symptoms due to
a) thyroid hormone's stimulation of catabolism
b) enhancement of sensitivity to catecholamines

2

Hyperthyroidism signs in pts under 50 (9)

- heat intolerance
- tachycardia
- fatigue
- weight loss
- tremor
- increased sweating
- exertional dyspnea
- decreased menses
- diarrhea

3

Older patients (>70) symptoms of hyperthyroidism

- sinus tachycardia
- fatigue or insomnia
- asymptomatic

4

exophthalmos = proptosis

Most often seen in Grave's
either bilateral or unilateral

5

Causes of enlarged thyroid = goiter

- lack of iodine
- hypothyroidism
- hyperthyroidism
- nodules (single or multiple)
- thyroid cancer
- pregnancy
- thyroiditis

6

Lack of iodine

Worldwide most common cause of goiter and also causes developmental delay and mental retardation
- most affected in N Africa and Pakistan
- prevent with supplemental iodine

7

Clonus

Series of abnormal reflex movements of the foot induced by sudden dorsiflexion causing alternate contraction and relaxation of gastrocnemius and soleus muscles

8

HPA axis effect on thyroid

Hypothalamus secretes TRH which stimulates pituitary to produce TSH which stimulates thyroid gland to release T3 and T4

9

TSH increased
T4 decreased

Hypothyroidism

10

TSH mildly elevated
T4 normal

Subclinical hypothyroidism

11

TSH normal
T4 increased

Pituitary adenoma (TSH producing) OR thyroid hormone resistance
- need to assess Sx further

12

TSH decreased
T4 increased

Hyperthyroidism

13

TSH decreased
T4 decreased

Central hypothyroidism (TRH deficiency) or
Pituitary hypothyroidism (TSH deficiency)

14

TSH decreased
T4 normal
T3 increased

T3 toxicosis

15

Primary symptoms of eye manifestations of Graves

Related to corneal irritation from eyelid retraction

16

Special info about exopthalmos

- While 50% of patients with Graves' have some eye involvement by MRI, only about 20-30% of those are clinically relevant.
- In up to 10% the eye manifestations can happen when the patient is euthyroid or even
hypothyroid.
- Treatment of hyperthyroidism does not affect the eye manifestations.
- In fact, in some
patients who get radioactive iodine, will experience worsening symptomatology.

17

Graves' Disease

- autoimmune disease in which thyrotropin receptor Abs (thyroid stimulating Igs) are produced --> make more thyroid hormone

18

Graves' epidemiology

- women 5-10x more likely to get it
- peak incidence between 40-60
- often occurs w family Hx of thyroid disease
- can be associated with other autoimmune diseases

19

Graves' triggers include (3)

- stressful life events
- high iodine intake
- recent pregnancy

20

Sx of hypothyroidism (5) due to slow metabolism

- weight gain
- cold intolerance
- pedal edema
- heavy periods
- fatigue

21

Fatigue present in hyper, hypo, or both

Present in both hyper and hypothyroidism

22

How to elicit lid lag

- patient follows your finger w eyes: move finger from upper to lower field of vision - upper eyelid will lag behind upper edge of iris as eye moves downward

23

Pay special attention to Hx if (2)

- teenager was giving history of abstinence in presence of parent
- partner in room

24

Cardiac causes of palpitations

- arrhythmia
- cardiomyopathy
- hypovolemia

25

Psych causes of palpitations

- anxiety
- panic attacks

26

Med causes of palpitations

- caffeine
- stimulants
- theophylline
- albuterol

27

Substance causes of palpitations

- tobacco
- caffeine
- alcohol intox
- alcohol withdrawal
- cocaine

28

Endocrine causes of palpitations

- hyperthyroidism
- pheochromocytoma
- hypoglycemia

29

Hematologic causes of palpitations

- anemia

30

Infectious causes of palpitations

- febrile illness

31

Cardiac arrhythmias

- cause palpitations when HR is fast
- can be assoc with dizziness or SOB

32

How to differentiate anxiety/panic disorder from hyperthyroidism

Hyperthyroidism will have presence of systemic symptoms such as weight loss, changes in stool, changes in menses

33

Anemia causes palpitations because of...

Associated with...

- sinus tachycardia due to reduced oxygen carrying capacity in blood (also causes dyspnea this way)

- positional dizziness (unlike hyperthyroidism)

34

Causes of anemia

- weight loss leading to nutritional deficiencies (B12, folate)
- malignancy
- heavy periods
- bleeding from GI tract

35

Palpitations due to drugs(meth, cocaine)/caffeine

- pupil dilation
- increased energy
- increased BP
- erratic behavior

36

Common causes of hyperthyroidism (5)

1. Toxic diffuse goiter
2. Toxic nodular goiter
3. Thyroiditis
4. Excessive iodine ingestion
5. Drug induced hyperthyroidism

37

Toxic diffuse goiter (Grave's)

Autoimmune disease: antibody acts @ TSH receptor --> gland synthesizes excess thyroid hormone
Features include:
- hypervascularity of thryoid that results in bruit or thrill upon auscultation
- Exophthalmos
- Pretibial myxedema (deposition of hyaluronic acid in dermis and subcutaneous tissue)

38

Toxic nodular goiter

Older patients have multinodular disease
Younger patients have solitary nodules (can be associated with iodine deficiency)

39

Excessive iodine ingestion

Through diet or drug: amiodarone

This can induce thyroiditis

40

Radioactive iodine uptake test and scan

Measures amount of radioactive iodine taken up by the thyroid in 24 hrs - allow for differentiation between various etiologies of hyperthyroidism

41

Normal RAIU uptake

15-30% of ingested dose

42

High RAIU (>30%)

Increased creation of thyroid hormone results in increased radioactive iodine uptake used to synthesize thyroid hormone
- Graves
- Active nodules
- TSH secreting pituitary tumor
- HCG secreting tumor

43

Low RAIU (<15%)

Excess circulating thyroid hormone in thyroiditis leads to leakage of hormone so radioactive iodine is low
- thyroiditis
- exogenous L thyroxine
- struma ovarii
- amiodarone

44

Studies not used to determine etiology of hyperthyroidism

Ultrasound, MRI

45

Ultrasound of thyroid indicated for

Evaluation of nodules and thyroid enlargement (but not hyperthyroidism), stratify risk of malignancy, guide FNA

Starting to use color flow Doppler ultrasound to replace RAI when it is not available or contraindicated

46

Pregnancy and thyroid treatment

PTU first trimester
Methimazole after

47

Most commonly used medication to suppress thyroid function

Methimazole

48

Methimazole side effects

Agranulocytosis: bone marrow stops producing white blood cells - patient is vulnerable to serious infecitons

49

How long does it take to suppress thyroid production in hyperthyroid patients?

3 months, but symptom relief typically occurs within one month

50

Hyperthyroid patients need to stay on medications for...

Several years - more than 1/2 will return to hyperthyroidism if they try to stop medications

51

Treatment of Graves' disease

1) Meds such as methimazole or PTU (Europe)
2) Oral dose of radioactive iodine (US)

52

Radioactive iodine

Alternative to thyroid hormone suppressant medication
Iodine destroys most overactive thyroid cells - the level of thyroid hormone falls and the gland shrinks in size
- may have too little functioning thyroid and need thyroid hormone replacement - warn patients of hypothyroid symptoms
- once TSH is in normal range, can check once yearly

53

Radioactive iodine precautions with pregnancy

- obtain pregnancy test first
- patients should not be near pregnant women or young children several days following radioactive iodine treatment bc it is secreted in urine or stool - it will have bad effects on exposed kids thyroids

54

Radioactive iodine side effects

- transient soreness of neck or brief worsening of symptoms but should resolve in few days
- worsening eye sx in pts w opthalmopathy

55

Draw TSH post radioactive iodine..

once every 2-3 months until it stabilizes
- once in normal range, check once yearly

56

Thyroid replacement thyroid

Thyroxine in primary hypothyroidism (this is what follows radioactive treatment)

57

How to dose and manage thyroxine in hypothyroid patient

- 1.5-1.8 mcg/kg
- increase dose slowly
- repeat TSH in 6 weeks
- when stable TSH level achieved, check TSH 1-2/year

Note: some people who have RAI will have enough thyroid left to relapse - occasionally they need a second treatment