Thyroid Related Disorders (Hypothyroidism & Hyperthyroidism)

The thyroid hormone is an incredibly important hormone in our body. A disorder of this hormone can impact our bodies in unimaginable ways. In this blog post, we shall discuss Hypothyroidism and Hyperthyroidism and other thyroid hormone related disorders including their symptoms, diagnosis and their management. 

This is a high-yield topic for Surgery subject and it is highly important for NEET PG exam Preparation.

Let’s begin with the function of the thyroid hormone.     

What is the function of the thyroid hormone?

To control the basic metabolic rate. They convert mass into energy. That’s why hypothyroidism patient has too much mass  and weight gain despite of decreased appetite. In Hyperthyroid patient, the mass is converted into energy.That’s why they are more energetic.

Signs and Symptoms

Hypothyroidism (decrease in BMR)

Weight gain, decrease appetite, confusion, middle ear effusion, bradycardia, diastolic hypertension , constipation, menorrhagia, loss of hair

Hyperthyroidism (Increase in BMR)

Weight loss, increase appetite, increase expression of beta receptors that cause increase in sympathetic stimulation (tachycardia, increase sweating, heat intolerance), diarrhea, amenorrhoea,  increase risk of abortions and infertility

Graves Disease

Most common cause of Hyperthyroidism worldwide. Is known as diffuse toxic goitre. It is an autoimmune disorder, associated with long acting thyroid stimulator antibody (LATS) against TSH receptor. It is also associated with HLA DR3. 

Characteristic features

• Thyrotoxicosis
• Exoophtalmous (collection of loose areolar tissue behind the eyeball, protrusion of the eyeball)
• Dermopathy (known as pretibial myxedema, deposition of glycosaminoglycans  over the shin of tibia and dorsum of foot)
• Acropatchy- subperiosteal new bone formation in meta carpas
• Gynaecomastia

Pathophysiology

TSH works on TSH receptor. In Graves disease there is autoantibody against TSH receptor, which stimulate TSH receptor. As a result there will be increase secretion of T3 and T4, which cause feedback inhibition on TSH, which cause decrease in TSH. The patient will be having hyperthyroidism and sympathetic stimulation. 

Clinical Features

• Tachycardia
• Palpitation
• Excessive sweating
• Fine tremors in the fingers and the tongue

Signs and symptoms in females

• Amenorrhea
• Increased risk of abortions
• Infertility

Signs and symptoms in children

• Early growth and maturation
• CNS symptoms predominant in young patients 

Signs and symptoms in elderly

•  CVS symptoms predominant in elderly (AF and CHF)

Two important features in Thyroid gland

1. Hyperactive- there is increased RAI uptake
2. Hypervascular- most prominent at upper pole. There will be palpable thrill, audible bruit and audible venous hum

Diagnosis

The presence of eye signs in patient of hyperthyroidism. Presence of auto antibody  is  single investigation to confirm the diagnosis

Management

 Non selective beta blockers (Propranolol)are used for sympathetic stimulation. Anti thyroid drugs are given for thyroid related symptoms.. Symptomatic improvement occurs within 2 weeks. Patient become euthyroid in 6 weeks. Drugs used are Methimazole, Carbimazole, Propyl thiouracil

Side effects of drugs

Agranulocytosis,  with Methimazole there is increased risk of choanal atresia and aplasia cutis. Therefore methimazole is contraindicated in pregnancy. Propylthiouracil blocks conversion of T4 to T3, it is very helpful in hyperthyroidism, but there is increase risk of hepatic failure in females and children. Therefore this drug is contraindicated in females and children and can only be used in emergency crisis like Thyrotoxicosis . Anit thyroid drug used in pregnancy is Carbimazole, In Graves disease - Methimazole and PTU in thyrotoxic crisis. Treatment of choice in Graves disease is total thyroidectomy. Alternative treatment is RAI ablation. 

Indications of RAI ablation

• Elderly patient
• Patient with surgical comorbidity
• Recurrence after surgery

Contraindications of RAI ablation

1. Absolute

• Pregnancy
• Lactation

2. Relative

• Young patients
• Smokers
•  Ophthalmopathy (There is worsening of ophtahlmopathy after RAI ablation)

Hashimoto Thyroiditis (Struma Lymphomatosa)

Most common cause of Hypothyroidism worldwide. Conversion of thyroid tissue into Lymphoid tissue. It is an autoimmune disorder and autoantibody  related is Anti thyroid peroxidase (Anti TPO). It is associated with HLAB8/ DR3 and DR5. 

Pathophysiology

There is CD4 mediated CD8 cytotoxicity, because of this CD8 cytotoxicity there is permanent destruction of thyroid follicle. These patients going to develop permanent hypothyroidism. So Levothyroxine is given lifelong. It increases the risk of 2 malignancies Thyroid lymphoma and Papillary carcinoma. 

Clinical Features

Signs and symptoms of hypothyroidism  and mild enlargement of thyroid gland leading to increase circumference of neck.

Diagnosis 

Presence of autoantibodies (Anti- TPO) are diagnostic. In FNAC there is increased in lymphocytic infiltration and characteristic cells Askanazy, Hurthle  are present. 

Management

Lifelong Levothyroxine  should be given. If there is increased suspicion of malignancy, in such cases go for total thyroidectomy. 

ACUTE SUPPURATIVE THYROIDITIS

It is caused by bacteria. Most common organism involved Staph. Aereus followed by Streptococci. It is more common in childrens because some children are having persistent pyriform sinus, which connects oral cavity to thyroid. Any child having otitis media or upper respiratory tract infection. They are increased risk of acute suppurative thyroiditis. Bacterial infection to thyroid gland is rare as thyroid gland is resistance to infection because there is rich vascular supply, high iodine content and there is fibrous capsule but can be seen in immunocompromised patients (transplant recipient, suffering from malignancy or on steroids)

Route of infection on Suppurative thyroidits 

• Hematogenous or Lymphatic spread
• Direct spread (Persistent pyriform sinus or infection in thyroglossal cyst)
• Penetrating trauma
• Immuno compromised patients

Signs and symptoms

Pain, tenderness over thyroid region, fever with chills and rigor. 

Diagnosis

Increased neutrophils are seen in FNAC

Management

Incision and drainage plus antibiotics.If there is recurrence rule out persistent pyriform sinus by barium swallow and perform excision

Subacute Thyroiditis

Also knwn as De Quervain, viral, granulomatous or giant cell thyroiditis. These are predisposed by upper respiratory tract infection caused by virus. In FNAC muti nucleated giant cells are detected. It is associate with HLA B35

Stages

• Because of follicle destruction , release of T3 and T4- Hyperthyroid
• T3, T4 used up-Euthyroid
• Destruction of follicle-Hypothyroid
• More than 90% patient, spontaneous resolution- Euthyroid

Clinical Features

Pain and tenderness over thyroid,and signs, symptoms of hypo or hyperthyroid depending upon the stage of disease. 

Investigation

FNAC- multinucleated gaint cells 

Management

To control inflammation -NSAIDs and steroids for non responding patients

Reidels Thyroiditis

Also known as Invasive fibrous thyroiditis. In this condition thyroid and parathyroid glands are completely replaced by fibrous tissue. Patient will develop permanent hypothyroidism as well as permanent hyperparathyroidism. Assocaited with retro orbital fibrosis, peri orbital fibrosis, retroperitoneal fibrosis and sclerosing cholangitis

Clinical Features

Patient will develop signs and symptoms of hypothyroidism and parahypothyroidism. On palpatation, hard and woody thyroid, which cause compression in the midline structure. Patient will develop dyspnea, dysphagia, hoarseness of voice.  

Investigation

Since it cannot be diagnosed by FNAC, so perform wedge shaped excision biopsy (WSEB). The advantage of WSEB is, that it will release compression symptoms

Management

Hypothyroidism- lifelong Levothyroxine and for hypoparathyroidism- lifelong calcium and Vit D supplementation

And that is everything you need to know about hypothyroidism, hyperthyroidism and other thyroid hormone related disorders including their clinical features, investigation and management. 

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