Goiter

Mass of thyroid gland; Goiter - Chronic
Rahul Soman, M. Pharm

 

Definition  

Thyroid disease may present as diffuse enlargement (goiter) of the thyroid or as 1 or more discrete lesions (nodules), or as a combination of both. A thyroid nodule is defined as a palpable lump (generally >1 cm), which is caused by an abnormal, focal growth of thyroid cells, involving 1 or multiple areas of the gland .

 

Medical History  

* Dietary iodine deficiency

* Smoking

* Past exposure to ionizing radiation

* Pregnancy

* Family history of Disorder of thyroid gland

* Congenital hypothyroidism

 

Findings  

* Goiter

* Thyroid nodule

* Fatigue

* Weight change finding

* Dry skin

* Coarse hair

* Diaphoresis

* Intolerant of cold

* Intolerant of heat

* Asthenia

* Bradyarrhythmia

* Sinus tachycardia

* Palpitations

* Hypotension

* Dependent edema

* Yellow skin

* Puffiness of skin

* Warm skin

* Constipation - Chronic

* Diarrhea

* Altered appetite

* Hypothermia

* Myalgia

* Ankle reflex delayed

* Tremor

* Proximal muscle weakness

* Visual alteration

* Depression - Chronic

* Poor concentration

* Memory impairment

* Irritability

* Feeling nervous

* Dyssomnia

* Dyspnea - Chronic

* Irregular periods

* Excessive and frequent menstruation

* Light and infrequent menstruation

* Oligomenorrhea

* Infertility - Chronic

* Alopecia - Chronic

* Dysphagia - Chronic

* Pretibial myxedema

* Difficulty speaking

* Hoarse

* Ataxia

* Sleep apnea

* Periodic paralysis

* Strabismus

* Exophthalmos

* Soft tissue swelling

* Jugular venous distention

 

Tests  

Suspected or known hypothyroidism  

* Thyroid stimulating hormone measurement: Overt hypothyroidism is classified as a TSH above the upper limit of the reference range in the presence of a low serum free thyroxine (FT4) . Subclinical hypothyroidism is a laboratory diagnosis defined as a TSH above the upper limit of the reference range in the presence of a normal FT4.

 

Suspected hyperthyroidism  

* Thyroid stimulating hormone measurement: Overt hyperthyroidism is defined as a serum TSH less than 0.1 milliunits/L (mU/L) in the presence of an elevated serum free thyroxine (FT4), thyroxine (T4), or serum free triiodothyronine (FT3). Subclinical hyperthyroidism is defined as a TSH below the statistically defined lower limit of the reference range in the presence of a normal FT4 and FT3.

 

Suspected hyperthyroidism in patients with atrial fibrillation  

* Thyroid stimulating hormone measurement: A TSH level ?0.1 milliunits/L (mU/L) is associated with an increased risk of atrial fibrillation .

 

Suspected or known hypothyroidism  

* Serum free T4 measurement: Free thyroxine (FT4) is decreased in conjunction with an elevated TSH level in primary hypothyroidism and in conjunction with a low, normal, or slightly elevated TSH level in secondary hypothyroidism .

 

Evaluation of patients with a palpable thyroid nodule, multinodular goiter, adenopathy suggestive of a malignant lesion, or high-risk patients  

* US scan of thyroid: Ultrasound is the most sensitive test available to detect thyroid nodules, accurately measure lesions, identify their structure, and note diffuse changes within the gland .

 

Thyroid nodule  

* Fine needle biopsy of thyroid: Fine needle aspiration of the thyroid results can be interpreted as benign, malignant, suspicious, or nondiagnostic .

 

Suspected medullary thyroid cancer  

* Serum calcitonin measurement

 

Differential Diagnosis  

* Multinodular goiter

* Malignant tumor of thyroid gland - Chronic

* Hashimoto thyroiditis - Chronic

* Graves' disease

* Toxic multinodular goiter

* Malignant lymphoma of thyroid gland

* Secondary malignant neoplasm of thyroid gland

* LITHIUM SALTS

* Subacute thyroiditis

* Postpartum thyroiditis

* Thyroid follicular adenoma

* Cyst of thyroid

* Tuberculosis - Chronic

* Thyroid hormone resistance syndrome

* Amyloidosis - Chronic

* Scleroderma - Chronic

 

Treatment  

 

Drug Therapy  

 

Hypothyroidism  

 

LEVOTHYROXINE SODIUM  

Adults: 1.7 mcg/kg/day orally once daily (usual maintenance dose is 100 to 200 mcg/day) to maintain serum levels of TSH of 0.4 to 2 milliUnits/L

 

 

Thyroid stimulating hormone suppression therapy in patients with benign nodules and nontoxic multinodular goiter  

 

LEVOTHYROXINE SODIUM  

Adults: Doses greater than 2 mcg/kg/day orally are used to suppress TSH (eg, 0.1 to either 0.5 or 1 milliUnits/L

 

Hyperthyroidism  

 

METHIMAZOLE

Adults: 15 to 30 mg/day orally initially; after achieving normal thyroid function, decrease the dose as tolerated

 

Hyperthyroidism  

 

PROPYLTHIOURACIL

Adults: 100 mg orally 3 to 4 times daily as initial therapy; after achieving normal thyroid function, decrease the dose as indicated

 

Thyroid storm  

 

METHIMAZOLE

Adults: 60 to 120 mg orally or rectally once daily or in divided doses

 

Thyroid storm  

 

PROPYLTHIOURACIL  

Adults: 60 to 120 mg/day orally or rectally in 3 or 4 divided doses

 

Procedural Therapy  

 

Patients with a functioning benign thyroid nodule regardless of the presence of hyperthyroidism or those with hyperthyroidism related to Grave disease or a toxic multinodular goiter  

* Iodine 131 therapy: Iodine 131 therapy may be effective in patients with a functioning benign thyroid nodule in patients with or without hyperthyroidism .

 

Patients with suspicious or malignant cytology or those with a large symptomatic or cosmetically unacceptable thyroid mass  

* Thyroidectomy: Thyroidectomy is indicated for patients with malignant or suspicious cytology as well as for patients with rapid growth of a benign large solid nodule .

 

Patients with papillary or follicular thyroid cancer who have undergone thyroidectomy  

* Radionuclide ablation of thyroid gland: Radioiodine ablation therapy following thyroidectomy for follicular-derived thyroid cancer may eliminate microscopic residual or metastatic thyroid cancer cells .