Endocrine and Metabolic Diseases Flashcards
(124 cards)
What is the most common cause of Hyperthyroidism (80%), and what is the pathophysilogy?
Graves disease (diffuse toxic goiter).
An autoimmune disorder; Thyroid stimulating immunoglobulin (IgG) antibody binds to TSH receptors on the surface of thyroid cells, and triggers synthesis of excess thyroid hormone.
What does Graves disease typically show on radioiodine scan?
Diffuse uptake, because every thyroid cell is hyperfunctioning.
What is the 2nd most common cause of Hyperthyroidism (15%)? What is the pathophysiology?
Plummer disease (multinodular toxic goiter).
Hyperfunctioning areas that produce high T4 and T3 levels, thereby decreasing TSH. As a result, the rest of the thyroid is not functioning -> atrophy.
What does Plummer disease (multinodular toxic goiter) typically show on radioiodine scan?
Patchy uptake
Name 4 other causes of Hyperthyroidism
- Toxic thyroid adenoma (single nodule)
- Hashimoto thyroiditis and subacute (granulomatous) thyroiditis - causes transient hyperthyroidism)
- Postpartum thyroiditis
- Excessive doses of levothyroxine
Clinical Sx of hyperthyroidism
Nervousness Insomnia Tremor Irritability Hyperactivity Sweating Heat intolerance Weight loss, incr. appetite Diarrhea Palpitations Muscle weakness
Clinical signs of hyperthyroidism
- Thyroid gland:
- Graves: diffusely enlarged (symmetric), nontender thyroid, bruit may be present.
- Subacute thyroiditis: tender, diffusely enlarged gland (with a viral illness)
- Plummer: bumpy, irregular and asymmetric (if multinodularity)
- Extrathyroidal:
- Proptosis, due to edema in the extraocular muscles + retroorbital tissue
- Arrhytmias, elevated BP
- Brisk DTR, tremor
Diagnosis of hyperthyroidism
Test TSH and T4. Most important. TSH should be low and T4 should be elevated.
Radioactive T3 uptake can be donw if you want to differentiate between elevations in thyroidhormones due to increased TBG from true hyperthyroidism (due to an actual increase in free T4.)
Treatment-types of hyperthyroidism
- Pharmacologic
- Methimazole and PTU
(inhibit thyroid hormone synthesis and conversion of T4 to T3). (side effect Agranulocytosis)
- B-blockers
(for acute/uncomfortable sx) - Sodium ipodate or iopanoic acid
- Fast acting, appropriate for acute mx of severe hyperthyroidism that is not responding to conventional therapy.
- Radioiodine 131
- Destroys thyroid follicular cells
- Main complication is hypothyroidism - Surgical - subtotal thyroidectomy
- Effective, but many get permanent hypothyroidism etc.
- Watch for clinical sx of hypocalcemia, due to parathyroid inflammation or accidental removal.
Most serious side effect of Thionamides (Methimazole and PTU)
Agranulocytosis
Which tx is contraindicated in pregnancy?
Radioiodine 131 (due to risk of cretinism).
What is typical “side-effects” of subtotal thyroidectomy
- Permanent hypothyroidism
- Recurrence of hyperthyroidism
- Recurrent laryngeal nerve palsy
- Permanent hypoparathyroidism
- Hypocalcemia (parathyroid)
In immediate control of adrenergic symptoms of hyperthyroidism, you give:
B- blockers
What do you give to nonpregnant patients with Graves?
a) Methimazole + B-blocker
b) Stop B-blocker after 4-8w (when Methimazole starts to work)
c) Continue methimazole for 1-2y. Measure TS-IgG at 12m. If absent, discontinue therapy.
What do you give to pregnant patients with Graves?
a) Endocrinology consult indicated before starting tx
b) PTU is preffered! (Pregnant = Ptu)
Which patients may benefit by Radioactive iodine?
- Elderly patients
- Patients with a solitary toxic nodule
- Patients with Graves disease in whom therapy with antithyroid drugs fails.
What is thyroid storm?
Sx?
Rare, life-threatening complication of thyrotoxicosis characterized by an acute exacerbation of the manifestation of hyperthyroidism.(mortality rate up to 20%)
Sx: Marked fever, tachycardia, agitation, psychosis, confusion, diarrhea, vomiting, nausea
What can cause a thyroid storm?
Precipitating factors such as infection, diabetic ketoacidosis, stress (e.g surgery, trauma, illness, childbirth)
Treatment of a thyroid storm
- IV fluids
- Cooling blankets
- Glucose
- PTU every 2h
- Iodine to inhibit thyroid hormone release.
- B-blockers for control of HR
Most common cause of Primary hypothyroidism? (95%) Pathophysiology?
Hashimoto disease (chronic thyroiditis) - failure of the thyroid to produce sufficient thyroid hormone.
Second most common cause of Primary hypothyroidism? + examples
Iatrogenic. Results from prior tx of hyperthyroidism, including:
- Radioiodine therapy
- Thyroidectomy
- Medications (e.g lithium)
What is secondary hypothyroidism?
Due to pituitary disease, i.e., deficiency of TSH
What is tertiary hypothyroidism?
Due to hypothalamic disease, ie., def. of TRH.
What are typical findings of secondary and tertiary hypothyroidism?
Both are associated with a LOW free T4 and a LOW TSH level.