Thyroid Disease Flashcards by Stephanie Escobar

Pt presents with headache, visual disturbances, palpitations, tremor, and enlarged thyroid.
↑/– TSH
↑ T3/T4

Diagnosis?

TSH-secreting pituitary adenoma

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Fine-needle aspiration thyroid biopsy reveals large cells with ground glass cytoplasm, and pale nuclei containing inclusion bodies and central grooving consistent with ___. NBSIM?

papillary thyroid cancer
Thyroidectomy

(if high recurrence risk)
± radioiodine ablation + Levothyroxine

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Pt presents with history of 1st Trimester miscarriages and non-tender thyroidmegaly.

↑ TSH
T4 wnl

Diagnosis? Treatment?

chronic lymphocytic/autoimmune thyroiditis
(Hashimoto thyroiditis)
(Subclinical)

–anti-TPO antibodies
–antithyroglobulin antibodies

Levothyroxine (even if subclinical) in pts with elevated anti-TPO antibodies.

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Hypothyroidism can cause elevated levels of ____.

total cholesterol, LDL, & triglycerides
(↑ risk of CAD)

Levothyroxine can improve lipid levels, although normalization may take several months

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Pt presents with anxiety, weight-loss, palpitations, tremor, and enlarged, non-tender thyroid.
↓ TSH
↑ T3/T4

↑ Radioactive iodine uptake at 24 hours and homogenously distributed.

Diagnosis? Treatment?

Graves disease

Propranolol
+
Propylthiouracil or Methimazole

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Patients with mild Graves disease, small goiters, and low TSH receptor antibody titers can be managed with ___.

Propylthiouracil or Methimazole
alone with 50% of remission.

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In patients with Graves disease who have significant symptoms and T3/T4 level >2-3x normal

Definitive treatment is ___.

Propranolol
+
Propylthiouracil or Methimazole

to stabilize the patient before
definitive treatment with RAI (adioactive iodine) or thyroidectomy.

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Common post-surgical thyroidectomy complication

hypoparathyroidism → hypocalcemia

(presents with fatigue, anxiety, or depression; tetany of lips, face, and extremities; seizures)

ECG → QT-interval prolongation

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Fever and sore throat in any patient taking antithyroid drugs (PTU or MMZ) suggests ____.

agranulocytosis

(d/c medication and get a CBC)

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Pt presents with anxiety, palpitations, weight-loss, and enlarged, non-tender thyroid gland
↓ TSH
↑ T4
Radioactive iodine uptake is <5% (low)
+ anti-thyroid peroxidase antibodies (high titers)

Diagnosis & NBSIM?

painless (silent) thyroiditis

Tx: Propanolol

RAIU scan (normal: 8%-25%)

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Pt presents with Hyperthyroid sxs
↓ TSH
↑ T4
+ Anti-TPO titers
+ Low RAIU

Diagnosis?

painless (silent) thyroiditis

(self-limited; can give propranolol for sxs)

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This thyroiditis presents the same as postpartum thyroiditis but by definition excludes patients within a year of pregnancy.

painless (silent) thyroiditis

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Primary hyperthyroidism can result from
↓ TSH
↑ T4

Overproduction of thyroid hormone (2)

Release of preformed hormone (2)

Overproduction → Graves disease, toxic nodular goiter

Preformed Released → painless thyroiditis, subacute (deQuervains) thyroiditis

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Thyrotoxicosis (↑T4) with normal or ↑ RAIU
(3)

Graves disease
Toxic multinodular goiter
Toxic nodule

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Thyrotoxicosis (↑T4) with ↓ RAIU
(3)

Painless (silent) thyroiditis
Subacute (de Quervain) thyroiditis
Excessive dose (or surreptitious intake) of levothyroxine

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This thyroiditis is characterized by fever, neck pain, and a tender goiter following an upper respiratory illness.
Patients have a self-limited thyrotoxic phase followed by hypothyroidism and eventual recovery of thyroid function.
Diagnosis and Treatment?

Subacute (de Quervain) thyroiditis

Beta blockers (for sxs)

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Levothyroxine requirements ____ during pregnancy.

increase

(Pts should increase their levothyroxine dose at the time pregnancy is detected)

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Radioiodine therapy for Graves disease can acutely worsen Graves ____ due to increased titers of thyroid-stimulating autoantibodies.

ophthalmopathy

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The initial evaluation of thyroid nodules includes (2).

serum TSH levels
thyroid ultrasound

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Thyroid Nodule + ↓TSH →

radionuclide thyroid scan (scintigraphy)

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Thyroid Nodule + ↑/– TSH →

Fine Needle Aspiration

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A small, hyperfunctioning (“hot”) nodule (increased isotope uptake in the nodule with decreased surrounding uptake) → NBSIM?

No FNA
(associated with a low cancer risk)

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A hypofunctioning (“cold”) nodule (decreased isotope uptake compared to surrounding tissue) → NBSIM?

FNA
(associated with a high risk of cancer)

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Systolic hypertension in thyrotoxicosis is caused by hyperdynamic circulation resulting from increased ____ and heart rate.

myocardial contractility

Antithyroid Drugs adverse effects: _____: 1st-trimester teratogen, cholestasis, agranulocytosis ______: Hepatic failure, agranulocytosis

Methimazole Propylthiouracil

Postpartum woman with: ↓ TSH ↑ T3/T4 Thyroid peroxidase antibody **positive** Thyrotropin receptor antibody **negative** Diagnosis and NBSIM?

Post-Partum Thyroiditis Tx: Propanolol (hyperthyroid phase) Levothyroxine (Hypothyroid phase)

___ is characterized by myalgias, proximal muscle weakness, and an **↑ creatine kinase** level.

Hypothyroid myopathy Pts have additional features of hypothyroidism (fatigue, delayed reflexes). **NBSIM: TSH and free T4 levels**

Prominent **fever** & **hyperthyroid** features hx of recent viral infection **Painful/tender goiter** ↓ TSH ↑ T3/ T4 ↓ radioiodine uptake (<5%) ↑ ESR & CRP

Subacute **Granulomatous** thyroiditis (de Quervain's thyroiditis) Tx: Propanolol Features of hyperthyroidism followed by features of hypothyroidism

Predominant **hypothyroid** features Diffuse, non-tender goiter ↑ TSH ↓/– T3/T4 Radioiodine uptake (decreased, patchy, irregular) (+) Anti- **thyroglobulin** (+) Anti-**TPO** antibody (+) anti-microsomal antibodies

Chronic autoimmune thyroiditis (Hashimoto thyroiditis) Tx: Levothyroxine

Predominant **hyperthyroid** features hx of auto-immune disorder Diffuse, non-tender goiter ↓ TSH ↑ T3/ T4 ↓ radioiodine uptake (<5%) (+) Anti-**TPO** antibody

Subacute **lymphocytic** thyroiditis (Painless/Silent thyroiditis) Tx: Propanolol Features of hyperthyroidism followed by features of hypothyroidism

**critically ill** or **post-op** patient ↓ T3 TSH & T4 (wnl) or ↓ TSH ↓ T4 ↓ T3 Diagnosis and Tx?

Euthyroid sick syndrome (low T3 syndrome) No treatment indicated s/t ↓ peripheral conversion of T4 to T3 (can be seen in pts on high dose IV glucocorticoids)

Reverse T3 is elevated in

Euthyroid sick syndrome (low T3 syndrome)

A high RAIU suggests de novo hormone synthesis due to Graves' disease (diffusely increased uptake) or toxic nodular disease (nodular uptake). In contrast, a low RAIU suggests either release of preformed thyroid hormone (ie, thyroiditis) or exogenous thyroid hormone intake. In such cases, the serum thyroglobulin level can make the distinction: elevated thyroglobulin is consistent with endogenous thyroid hormone release whereas decreased thyroglobulin suggests exogenous or factitious thyrotoxicosis.

EDit

**Secondary** Hyperthyroidism __ TSH __ T3/T4 NBSIM?

↑ TSH ↑ T3/T4 MRI of Pituitary

**Primary** Hyperthyroidism __ TSH __ T3/T4

↓ TSH ↑ T3/T4

**Primary** Hyperthyroidism but not classic Graves Disease presentation. NBSIM?

RAIU scintigraphy

↓ TSH ↑ T3/T4 (+) **TSH receptor** Antibodies ↑ RAIU scan (normal: 8%-25%) Diffuse pattern Diagnosis?

Graves disease

↓ TSH ↑ T3/T4 ↑ RAIU scan (normal: 8%-25%) Nodular pattern Diagnosis? (2)

Multinodular Goiter Toxic Adenoma

↓ TSH ↑ T3/T4 ↓ RAIU scan (normal: 8%-25%) **↑ Thyroglobulin** Diagnosis? (2)

Thyroiditis Excess Iodine

↓ TSH ↑ T3/T4 ↓ RAIU scan (normal: 8%-25%) **↓ Thyroglobulin** Diagnosis?

Excessive dose (or surreptitious intake) of thyroid hormone meds

Post-partum woman presents with anxiety, fatigue, irritability, constipation, and weight-gain. Vitals significant for HTN and Bradycardia. What is the NBSIM and why?

pt likely has Postpartum thyroiditis → get **TSH/T4 labs** (brief hyperthyroid to hypothyroid phase) we can rule out "psychological" etiology because pt has **bradycardia** which can't be explained by depression.

Diagnosis: Infants presents with apathy, weakness, hypotonia, large tongue, sluggish movement, abdominal bloating, and an umbilical hernia.

congenital hypothyroidism

Untreated **hyperthyroidism** in pts increases risk for ___ & **atrial fibrillation**.

osteoporosis (fragility fractures) rapid bone loss s/t ↑ **osteoclastic activity**

Large _____ thyroid nodules carry an increased risk of **malignancy** and require fine needle aspiration biopsy.

hypofunctioning ("cold")

Fetal hyperthyroidism can be seen in patients with active ______.

Graves disease (b/c TSH receptor antibodies can cross the placenta) (Nodular toxic adenoma pts do **not** have TSHR antibodies so this isn't a problem in pregnancy for them)

proximal muscle weakness/atrophy in the setting of clinical features of hyperthyroidism. Diagnosis?

Chronic **hyperthyroid** myopathy

In evaluating thyroid nodules, TSH levels and Thyroid Ultrasound need to be obtained 1st. **Thyroid Ultrasound** helps determine nodule **size** and **sonographic features**. High risk of **Malignancy** sonographic features include: ⬩microcalcifications ⬩ irregular borders ⬩internal vascularity If nodule is >1cm and has the above features **or** is a _____ nodule Do a **fine-needle aspiration (FNA) biopsy**.

>2 cm, noncystic nodule

A radionuclide scan is indicated in evaluation of a **thyroid nodule** only for patients with ___.

low TSH

**Hypothyroid** Patient with Irregular menstruation: __ TSH __ FSH & LH __ Prolactin

↑ TSH ↓ FSH & LH ↑ Prolactin ( ↓T3 ⇨ ↑TRH ⇨ ↑ TSH & Prolactin) (↑Prolactin ━┫FSH, LH, & ovulation)

___ may represent a mild, transient central hypothyroid state that functions to minimize catabolism in severe illness (adaption to non-thyroidal illness).

Euthyroid sick syndrome (ESS)

___ stimulates/increases **thyroxine-binding globulin** (TGB), leading to increased total (but **not free**) T4.

High Estrogen (Hormone replacement therapy, OCPs, Pregnancy)

Patients in a **thyroid storm** can develop fever, hemodynamic instability, AMS, cardiac arrhythmias, and ____.

Congestive heart failure (Tx: Propanolol → PTU → Potassium → Prednisone to lower peripheral conversion of T4/T3)

___ directly **stimulates TSH receptors**, causing increased production of total T4 and suppressing TSH.

hCG (seen in pregnancy) (Recall: Estrogen stimulates TGB)

**Estrogen** stimulates/increases **thyroxine-binding globulin** (TGB), leading to increased ____.

total (but **not free**) T4 (suppresses TSH levels)

Neonatal Thyrotoxicosis is caused by ___ which bind to infant's **TSH receptors** & cause excessive thyroid hormone release

Transplacental passage of maternal anti-TSH receptor antibodies (Maternal Graves Disease)

In neonatal thyrotoxicosis, affected infants are warm/moist, irritable, tachycardic, and gain weight poorly. ___ & ___ are given to symptomatic patients until the condition **self-resolves** over a few weeks to months.

Methimazole + β blocker

what is the most common cause of congenital hypothyroidism worldwide?

Thyroid dysgenesis

Congenital Hypothyroidism presents weeks to months after ___ wanes

maternal thyroxine