Thyroid Disorders Slide Show

Slide Transcript

1. Thyroid Disorders Slide Show Tapan A. Patel Cuong; Nguyen Mona Jamaldinian

2. Thyroid Gland

Second largest endocrine gland in body

Small butterfly shaped gland located at base of neck below the sternocleidomastoid muscles

Thyroid is controlled
by the hypothalmus
and pituitary

3. Functions

Stimulates & maintains metabolic processes

- Produces thyroid hormones T3-triiodothyronine and T4-thyroxine

- These hormones regulate metabolism & affect the growth and function of other systems in the body

Secretes calcitonin to lower serum calcium levels

Parathyroid gland secretes PTH to raise serum calcium levels

4. Functions

Metabolic stimulants of:

- Neural and skeletal development

- Oxygen consumption at rest

- Stimulating bone turnover by increasing formation and resorption

- Promoting chronitropic and ionotropic effects

- Increasing number of catecholamine receptors in heart

- Increasing production of RBC

- Altering the metabolism of carbs, fats, and protein

5. Hormones: T3 & T4

T3 (Triiodothyronine) & T4 (Tetraiodothyronine

- Stored in Follicles (round sacs) in the thyroid filled with thyroglobulin, a thyroid protein.

- - Dietary iodine enters follicles where they are stored as T3 and T4

- T4 is converted to T3 by peripheral organs such as kidney, liver, and spleen

- T3 is 10x more active than T 4

6. Hormones: T4 to T3

- Only 20% of total T3 is secreted by thyroid

- - Majority is formed from catalysis of T4 by 5’-iodthryonine deiodinase (highest activity in liver and kidney)

7. Hormones:

T4-thyroxine contains 4 iodine atoms

It is a slow-acting pre-hormone

T4 takes 4 days to peak in blood

- Half-life 7 days

Overall effects take 6 weeks

T3 is the active and faster-acting hormone

The immediate effects of T3 last 1-2 days

- Half-life 1.5 days

8. Iodine

Dietary Iodide is removed from the bloodstream by means of an active pump

The pump can concentrate iodide in the follicular sacs at 350x greater than the blood concentration

Oxidation of iodide by thyroid peroxidase converts iodide  iodine

Peripheral de-iodination of T4 to T3 is regulated by many factors including health, nutritional status, and other hormones

9. Hormones- TSH

- TSH is a pituitary hormone

- Controlled by TRH-thyrotropin releasing hormone from hypothalamus

- Functions to stimulate thyroid hormone production

- - May enlarge thyroid (goiter) when under producing

- Labs:

- - High TSH indicates low thyroid hormone= hypo

- - Low TSH indicates high thyroid hormone = hyper

10. Hormones-Calcitonin & PTH

Produced by thyroid to regulate serum calcium levels

Calcitonin stimulates movement of calcium into bone

Parathyroid hormone (PTH) opposite effect of calcitonin

11. Negative Feedback System The disruption of any of these mechanisms can cause abnormal levels of T3 and T4 leading to thyroid disease TRH T3 & T4 Thyroid TSH

12. Diseases

Hypothyroidism-Under Activity

Prevalence

- Affects 5-17% of population

- Females> Males

- Higher in >60 years old

Types

- Hashimoto’s thyroiditis

- Ord’s thyroiditis

- Postoperative hypothyroidism

- Postpartum hypothyroidism

- Iatrogenic hypothyroidism

13. Diseases

Hyperthyroidism- Over activity

Prevalence

- Affect 5-17% of population

- Females> Males

- More common in younger persons

Types

- Thyroid storm

- Graves disease

- Toxic thyroid nodule

- Plummers disease

- Hashitoxicosis

- De Quervain thryoiditis

- Iatrogenic hyperthyroidism

14. Labs 80-220ng/dL Bound & Free T 3 Total(T 3 ) 0.25-6.7U/mL Thyroid stimulating hormone TSH 22-34% Binding capacity of TBG T 3 Resin Uptake 80-220ng/dL Bound & Free T 3 Total T 3 (TT 3 ) 0.8-1.5 ng/dL Free T 4 Free T 4 (FT 4 ) 4.5-12.5mg/dL Bound & Free T 4 Total T 4 (TT 4 ) Normal Range Measurement Thyroid Function Test

15. Labs

Hyperthyroidism

-  FT4

-  TSH

Hypothyroidism

-  FT4

-  TSH

16. Hyperthyroidism-Types

Graves disease

- Most common form (70-80%)

- - Autoimmune disorder in which thyroid-stimulating antibodies are circulating in blood. These bind to thyroid cells and activate cells in the same manner as TSH.

- 7 times greater in women

- Peak onset is 20-30’s

17. Hyperthyroidism-Types

Can be caused by:

- Toxic multinodular goiter

- Solitary toxic nodule

- Thyroiditis

- Drug-induced thryotoxicosis

- Pituitary or trophoblastic tumors

18. Hyperthyroidism-Symptoms

Weight loss

Tachycardia

Bulging eyes

Nervous/Anxious

Insomnia

Intolerant of heat

Goiter

19. Goiter

A diet deficient in iodine

Increase in thyroid stimulating hormone (TSH) in response to a defect in normal hormone synthesis within the thyroid gland.

20. Thyroid Storm

Life threatening syndrome

Decompensated hyperthyroidism

Symptoms

- Hyperthyroid symptoms with agitation, confusion, delirium, psychosis

- Gastrointestinal: Nausea/Vomiting, Abdominal pain

- Tachycardia associated with CHF

21. Thyroid Storm Treatment

Antithyroids

- PTU 200-400mg po/NG q4-8h

- Methimazole 60-120mg/d PO/NG divided q6-8h

Potassium Iodide 2-5 drops PO/NG q6h

Lugol Solution-Strong Iodine10 drops po TID

Glucorticoids: block conversion of T4 to T3

- Hydrocortisone succinate 100-200mg IV q6-8

- Dexamethasone 2mg Po/IV q6-8h

- Esmolol: 500mcg/kg/min

- Propranolol 20-80mg/dose PO/NG q4-6h

22. Hyperthyroidism-Treatment

Drug Therapy

- Beta blocker

- - Atenolol 50mg-100mg po daily

- - Propranolol 20-40mg po TID

- Antithyroids

- - Methimazole 15-30mg po daily

- - Propylthiouracil (PTU) 300mg TID

23. Hyperthyroid-Treatment

Procedural Therapy

- Radionuclide albation of thyroid gland

- Total thyroidectomy

24. Methimazole

Methimazole prevents peroxidase enzyme from coupling and iodinating the tyrosine residues on thyroglubulin. Reduces T3 & T4 production.

Dosage

- 15-30mg PO daily

25. Methimazole

Adverse Effects

- Skin rash

- Loss of taste

- GI upset

- Drowsiness

- Decreased Platelets

antagonistic properties of Methimazole

26. Methimazole

Drug Interactions:

- Discontinue before treatment with radioiodine; affects uptake

- Amiodarone: Increases T3 and T4 serum levels

- Warfarin: enhanced due to vitamin K

27. Propylthiouracil -PTU

Thio-urea derivative

Preferred agent in pregnant women

DOC for severe thyrotoxicosis

Dosage

- Adults: 300-450mg/day divided q8h

- Severe cases: 600-1200mg/day

- Maintenance dose 100-150mg/day divided q 8-12 hours

Drug Interactions

- Similar to Methimazole

28. PTU

Adverse reactions

- Rash

- Itching

- Hives

- Agranulocytosis

- Vasculitis

29. Carbimazole-UK

Pro-drug converted to active form -methimazole

Dosage

- 15-40mg PO daily until normal function

- Reduce to 5-15mg po daily maintenance dose

Adverse Effects

- Bone marrow suppression

- Neutropenia

- Agranulocytosis

30. Sodium Iodide I-131 (Iodotope)

Quickly absorbed and taken up by thyroid

No other tissue capable of retaining radioactive iodine therefore low adverse effects

Dose

- Adult 75-150mCi/g of thyroid x estimated thyroid gland size

- 24hour radioiodine uptake

- Discontinue antithyroid therapy 3-4days before

31. Hypothyroidism

Types:

- Primary hypothyroidism

- - Most common cause

- - Failure of thyroid gland

- - Occurs primarily in women aged 30-50 years old

- - - Chronic autoimmune thyroiditis or Hashimotos disease is the most common primary hypothyroidism AND hypothyroidism overall

- Secondary Hypothyroidism

- Tertiary Hypothyroidism

- Other causes

32. Hypothyroidism-Symptoms

Fatigue

Weight Gain

Depression

Dry skin

Bradycardia

Constipation

Intolerant to cold

33. Hashimoto’s Disease

Autoimmune disorder in which antibodies are directed against a thyroid sites to :

- Inhibit thyroid peroxidase

- Inhibit effects of TSH

- Stimulate thyroid growth

34. Hypothyroidism-Primary

Drug induced

- Amiodarone, lithium, thiocyanates, phenylbutazone, sulfonylureas, PTU & methimazole

Iatrogenic

- Surgical removal of the thyroid gland and radiation treatment

35. Primary Hypothyroidism

Thyroid gland failure

- Decrease T3 & T4

- Increase TRH due to negative feedback

- Increased TSH due to decreased TRH

36. Secondary Hypothyroid

Pituitary failure

- Insufficient TSH release as a result of:

- - Pituitary tumors

- - Surgery

- - Pituitary radiation

- - Pituitary necrosis

- - Autoimmune mechanisms

37. Tertiary Hypothyroidism

Hypothalamic Failure- very rare

Insufficient TRH release as a result of:

- Trauma

- Irradiation

- Tumors

38. Hypothyroidism-Treatment

Drug Therapy

- Levothyroxine Sodium-DOC synthetic T4

- - Adults 1-1.5mgc/kg/day orally initially, adjust as needed. Average dose 1.6-1.8mcg/kg/day

- - Pediatrics 1-1.5mgc/kg/day. Average 4 mcg/kg/day

- Thyroid (Armour)

- - 30mg PO daily, increase 15mg q 2-3 week

- Liotrix (Thyrolar) synthetic combo T3 & T4

- - Thyrolar 1/2 (6.25/25mcg) start1 tab daily , increase PRN q 2-3 weeks.

- L-triiodothyronine (Cytomel) synthetic T3

- - 25mcg PO daily/ increase 12.5-25mcg daily every 1-2 weeks

39. Hypothyroidism-Treatment

Adverse Effects

- MI

- Osteopenia

- HA

Contraindicated

- Acute MI

- Treatment of obesity

- Uncontrolled HTN

40. Monitoring

Obtain baseline FT4, TSH, LFT, CBCs before initiation of therapy

Repeat FT4 and TSH after 4-6 weeks on therapy and 4-6 weeks after adjustments

Once euthyroid state obtain thyroid function test after 3-6 months

Source: https://www.slideshare.net/guest2c2a65/thyroid-disorders

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