Hyperthyroidism: Year 3 Surgery

• Thyroid and Parathyroid Disease is covered in Year 3 Surgery.

Learning Outcomes

• Describe the initial assessment of someone with thyroid or parathyroid pathology.
• Formulate a differential diagnosis list for thyroid/parathyroid pathology.
• Select the appropriate investigations for thyroid/parathyroid pathology.
• Explain the treatment principles for a patient with thyroid/parathyroid pathology.
• Employ communication, collaboration, and interventions as part of a multidisciplinary team to care for a patient with thyroid/parathyroid pathology.

Clinical Case 1: Hyperthyroidism

• A 36-year-old woman presents with palpitations and increased anxiety over the last three months.
• She has unintentionally lost 5kg and has trouble sleeping.
• A large goitre, acropachy of the hands, pretibial myxoedema, and protrusion of the eyes are noted on examination.

Hyperthyroidism

• Clinical manifestations are generally independent of the cause of hyperthyroidism.
• The most common cause of hyperthyroidism is Graves' Disease.
• Classical symptoms include heat intolerance, tremor, palpitation, anxiety, weight loss, and increased frequency of bowel movements.

Investigations for hyperthyroidism

• Bedside tests include ECG to check for tachycardia or atrial fibrillation, and monitoring of vital signs.
• Blood tests include thyroid function tests (TFTs) that show raised free T4 and low TSH.
• Autoantibodies: TPO indicates Hashimoto's, while TRAb indicates Grave's disease.
• Imaging: Thyroid ultrasound and Scintigraphy to check for increased uptake in Grave's disease.

TFT Interpretation

• High TSH, normal T4, normal T3 indicates subclinical hypothyroidism.
• High TSH, low T4, low/normal T3 indicates hypothyroidism.
• Low TSH, normal T4, normal T3 indicates subclinical hyperthyroidism.
• Low TSH, high/normal T4, high/normal T3 indicates hyperthyroidism.
• Low TSH, low/normal T4, low/normal T3 indicates secondary hypothyroidism.

Indications for Surgery in Thyrotoxicosis

• Surgery is indicated when patient is not responsive to medical treatment like carbimazole.
• If medical management is not advised, such as when a patient is planning pregnancy.
• When there is Refractory hyperthyroidism or carbimazole failure.
• Patient preference after doctor-patient discussion.
• Severe Ophthalmopathy is another indication for surgery.
• Type of Surgery: Total thyroidectomy for Grave's disease.

Clinical Case Continued

• A patient undergoes total thyroidectomy for Grave's disease and the initial post-operative course is uneventful.
• Six months later, the patient returns, reporting tiredness, feeling cold, a 6kg weight gain, and low mood.

Hypothyroidism

• The thyroid gland fails to produce enough thyroid hormone, resulting in slowed metabolism.
• Symptoms include fatigue, feeling cold, low mood, constipation, and weight gain.
• Primary causes include thyroiditis, treatment for hyperthyroidism, congenital issues, iodine deficiency, and Hashimoto's thyroiditis (autoimmune – TPO antibodies).
• Secondary cause is the failure of the pituitary gland to release Thyroid Stimulating Hormone (TSH).
• Management involves Levothyroxine (thyroid hormone replacement) to normalise TSH levels.

Clinical Case 2

• A 47-year-old woman presents with a left-sided thyroid swelling for the past six weeks.
• The swelling is painless.
• The swelling has been increasing in size.
• The patient reports hoarseness for the past 4 weeks and is a current smoker.
• Examination reveals a firm 3-4cm left-sided swelling of the lower neck that moves upon swallowing.

Differential Diagnosis of Neck Swelling

• Benign causes include toxic multinodular goitre, follicular adenoma, thyroglossal cyst, Graves' disease, and solitary toxic nodule.
• Malignant causes include papillary carcinoma (80%), follicular carcinoma (10%), medullary carcinoma (5-10%, associated with MEN 2), anaplastic carcinoma (1-2%, poor prognosis), lymphoma, and metastasis (rare).

Investigations for Thyroid Nodules

• Bedside tests include ECG.
• Blood Tests: Calcium, Thyroid function tests, Anti-thyroid antibodies [TPO (Hashimoto's) and TRAb (Grave's)].
• Imaging: Ultrasound with FNAC (fine needle aspiration cytology).
• Other: Results to be discussed at MDM.
• Ultrasound (US) showed a 4cm nodule in the central portion of the left lobe of the thyroid gland.
• FNAC showed irregular groups of follicular cells called Thy 3F.

Assessment of Thyroid Nodule involves clinical examination, radiology and pathology

• Clinical examination: Physical examination.
• Blood tests evaluate thyroid function, measuring thyroid-stimulating hormone, T4, and T3.
• Radiology: Ultrasound assessment.
• U1 on ultrasound indicates a normal or simple cyst.
• U2 indicates benign features.
• U3 indicates Indeterminate features like homogenous, hyperechoic, halo, and central vascularity
• U4 indicates suspicious features like solid/ hypoechoic with disrupted peripheral calcification, and lobulated outline
• U5 Suggestive of cancer. associated LN.
• Pathology (TIRADS/Thy)
• TIRADS 1 indicates Non-diagnostic
• TIRADS 2 is Non-neoplastic
• TIRADS 3a – Cytological atypia of uncertain significance (~90% Benign)
• TIRADS 3f – Follicular lesion / suspected follicular neoplasm (~80% Benign)
• TIRADS 4 - Suspicious of malignancy (80% Malignant)
• TIRADS 5 - Malignant

Thyroid Malignancy Overview

• Papillary carcinoma typically occurs in the 4th-5th decade.
  • Risk factors include radiation exposure and family history.
  • It metastasizes via lymphatics.
• Follicular carcinoma typically occurs in the 6th-7th decade, with F:M = 3:1.
  • Risk factors include radiation exposure, family history, and iodine deficiency.
  • It metastasizes haematogenously.
  • Metastases may cause hyperthyroidism.
• Medullary carcinoma is a neuroendocrine tumour of parafollicular C cells, associated with MEN-2, and typically presents with normal TFTs.
  • Patients must be investigated for other neuroendocrine tumours before surgery.
• Anaplastic carcinoma is aggressive, with mortality approaching 100%.

Thyroidectomy

Indications (4Cs):

• Cancer.
• Cosmesis.
• Carbimazole (and other treatment) failure.
• Compression of adjacent structures.

Complications:

• Haemorrhage (post-op haemorrhage, cut strap muscles).
• Recurrent laryngeal nerve palsy (unilateral hoarseness, bilateral intubation).
• Hypocalcaemia (perioral parasthesia, carpopedal spasm, tetany, Chvostek and Trousseau sign).

Post-Thyroidectomy Hypocalcaemia

• A patient undergoes thyroidectomy and complains of tingling in their fingertips, toes, and around their mouth.
• Blood tests reveal a calcium level of 1.7 mmol/L (ref range 2.15-2.55 mmol/L).
• Prescribe calcium replacement.

Clinical Case 3

• A 72 year old woman presents with generalised aches and pains, fatigue and forgetfulness and low mood.
• The patient is an ex-smoker with history of cholecystectomy and recurrent kidney stones.
• Recent antibiotics from GP for UTI.
• A recent DEXA scan showed osteopenia of the spine and hips.
• The patient is taking Ramipril 5mg OD for hypertension.

Further exam of patient in clinical case 3

• The patient appears tired and in mild distress.
• There is tenderness over the lumbar spine and lower extremities.
• Neurological exam shows slightly reduced deep tendon reflexes in the lower extremities.

Investigations for Hyperparathyroidism

• Bedside tests: Monitor the 24 hr urinary calcium levels.
• Raised corrected calcium.
• The level of PTH will be raised
• Imaging: Ultrasound and Sestimibi scan to evaluate function of parathyroid glands.

Causes of Primary Hyperparathyroidism:

• Solitary adenoma (87%).
• Multiple adenomas (3%).
• Four-gland hyperplasia (9% associated with MEN).
• Carcinoma (1%).

Presentation of Hypercalcaemia:

• Renal calculi.
• Fatigue, weakness.
• Forgetfulness.
• Low mood.
• Osteoporosis.

Symptoms:

• Stones, Bones, Groans and Psychic overtones

MANAGEMENT OF HYPERPARATHYROIDISM

• Acute:
  • IV fluids
  • Monitor urine output
  • Furosemide may be used once adequate hydration is achieved.

Definitive management

• Parathyroidectomy can be partial or total, with strict monitoring of post-op calcium levels as hypocalcaemia is common.

Secondary and Tertiary Hyperparathyroidism

• Secondary Hyperparathyroidism is associated with renal failure, where Vitamin D conversion in the kidney fails, leading to low calcium levels and reactive PTH secretion.
• This condition is usually corrected by renal replacement.
• Tertiary Hyperparathyroidism: occurs when hyperplasia becomes autonomous, classically seen after renal transplantation and the situation will be treated by 4 gland resection and auto-transplantation