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Hypertension
0/3
Mechanisms of Blood Pressure Regulation
07:36
Pathogenesis of Primary and Secondary Hypertension
41:56
End of Topic Quiz
00:20:00
Ischaemic Heart Disease
0/5
Atherosclerosis
14:37
Plaque Formation
06:06
Pathophysiology of Angina
09:44
Pathophysiology of Myocardial Infarction
11:49
End of Topic Quiz
00:20:00
Heart Failure Mechanisms
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Types of Heart Failure (Systolic vs. Diastolic)
09:06
Pathophysiological Changes in Heart Failure
07:56
Clinical Manifestations and Stages of Heart Failure
02:59
End of Topic Quiz
00:20:00
Alzheimer’s Disease
0/4
Pathogenesis of Alzheimer’s Disease
08:53
Genetic and Environmental Risk Factors
07:24
Clinical Stages and Symptoms
04:27
End of Topic Quiz
00:20:00
Parkinson’s Disease
0/4
Pathogenesis of Parkinson’s Disease
13:53
Motor and Non-Motor Symptoms
31:18
Risk Factors and Progression
03:43
End of Topic Quiz
00:20:00
Pain Pathways and Analgesia
0/5
Types of Pain
11:47
Pathways of Nociception
08:14
Mechanisms of Pain Modulation
24:13
Pharmacological and Non-Pharmacological Pain Management
24:16
End of Topic Quiz
00:20:00
Diabetes Mellitus
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Types of Diabetes
05:58
Pathophysiology of Hyperglycaemia
06:15
Acute and Chronic Complications
17:05
Management Strategies
05:54
End of Topic Quiz
00:20:00
Thyroid Disorders
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Hypothyroidism
05:39
Hyperthyroidism
12:07
Pathophysiology of Thyroid Hormone Synthesis and Regulation
07:53
End of Topic Quiz
00:20:00
Cushing’s vs Addison’s Disease
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Cushing’s Disease
13:41
Addison’s Disease
11:58
Key Differences Between Cushing’s and Addison’s Disease
15:40
End of Topic Quiz
00:20:00
Cardiovascular & Endocrine Pathophysiology

Introduction

  • Hypothyroidism, or underactive thyroid, occurs when the thyroid gland does not produce enough thyroid hormone for the body’s needs.
  • The thyroid gland is a small, butterfly-shaped gland at the base of the neck, just below the Adam’s apple.
  • The thyroid produces the hormones thyroxine (T4) and triiodothyronine (T3), which regulate the body’s metabolism, impacting numerous bodily functions.

Causes of Hypothyroidism

  • Autoimmune Disease: Hashimoto’s thyroiditis is the most common cause of hypothyroidism. This autoimmune disease involves the body’s immune system attacking the thyroid cells, impairing hormone production.
  • Medical Treatments: Hypothyroidism can result from treatments for hyperthyroidism, including:
    • Radioactive iodine treatment
    • Thyroidectomy (surgical removal of the thyroid)
    • Antithyroid drugs in excessive doses
  • Medications: Certain medications can contribute to hypothyroidism, such as:
    • Lithium (used for mental health conditions)
    • Amiodarone (used for heart problems)
    • Thalidomide
    • Checkpoint inhibitors like pembrolizumab and nivolumab (used for cancer treatment)
  • Other Causes:
    • Excess consumption of certain health foods (e.g., kelp)
    • Pituitary gland malfunction
    • Radiation therapy for head and neck cancers
    • Congenital hypothyroidism (present at birth due to thyroid gland underdevelopment or malfunction)
    • Thyroiditis (inflammation of the thyroid gland)
    • Iodine deficiency (iodine is essential for thyroid hormone production)

Symptoms of Hypothyroidism

Symptoms typically develop gradually and can be subtle, sometimes mistaken for normal ageing. The severity of symptoms varies depending on the degree of hormone deficiency.

Early Symptoms:

  • Fatigue and tiredness
  • Sensitivity to cold
  • Weight gain
  • Constipation
  • Depression
  • Slow movements and thoughts
  • Muscle aches, weakness, and cramps
  • Dry and scaly skin
  • Brittle hair and nails
  • Loss of libido (sex drive)
  • Carpal tunnel syndrome
  • Irregular or heavy periods

Later Symptoms (Less Common):

  • Low-pitched and hoarse voice
  • Puffy-looking face
  • Thinned or partly missing eyebrows
  • Slow heart rate (bradycardia)
  • Hearing loss
  • Anaemia
  • Elevated blood cholesterol levels

Hypothyroidism in Infants:

  • Feeding problems
  • Poor growth and weight gain
  • Jaundice
  • Constipation
  • Poor muscle tone
  • Dry skin
  • Hoarse crying
  • Enlarged tongue
  • Umbilical hernia

Hypothyroidism in Children and Teens:

  • Similar symptoms to adults
  • Poor growth leading to short stature
  • Delayed development of permanent teeth
  • Delayed puberty
  • Poor mental development

Diagnosis of Hypothyroidism

  • Physical examination: A doctor will check for a swollen thyroid gland.
  • Blood tests: Thyroid function blood tests are essential for diagnosis, measuring levels of:
    • Thyroid-stimulating hormone (TSH)
    • Thyroxine (FT4)
    • Thyroid antibodies (to confirm autoimmune cause)
  • Imaging tests: May be used to visualise the thyroid gland and identify any structural abnormalities:
    • Ultrasound
    • CT scan
    • Thyroid uptake scan

Subclinical Hypothyroidism (Mild Thyroid Failure):

  • Slightly elevated TSH level with a normal FT4 level.
  • May have no obvious symptoms but can progress to hypothyroidism over time.
  • Requires regular thyroid function tests and monitoring for symptom development.

Treatment of Hypothyroidism

  • Hormone Replacement Therapy: The primary treatment for hypothyroidism is levothyroxine, a synthetic form of thyroxine (T4).
    • Levothyroxine is generally safe and effective with minimal side effects when taken at the appropriate dose.
    • Dosage is individualised based on body weight and blood test results.
    • It may take several months for symptoms to improve and thyroid function tests to normalise.

Levothyroxine Administration:

  • Taken orally in the morning on an empty stomach with water, at least 30 minutes before eating or drinking.
  • Should be taken at least 4 hours apart from calcium, iron, cholesterol-lowering drugs, and multivitamins to avoid absorption interference.

Important Considerations:

  • Consistent daily intake of levothyroxine is essential for optimal treatment.
  • Missed doses are unlikely to cause immediate effects, but long-term inconsistency can impact health.
  • Once the correct dose is established, annual blood tests are needed for monitoring.
  • Levothyroxine dose adjustments may be necessary during pregnancy, menopause, or other conditions.

Long-Term Management

  • Patients are typically managed by their GP, but may be referred to an endocrinologist if complications arise.
  • Annual blood tests are necessary to monitor thyroid hormone levels.
  • Lifelong levothyroxine treatment is usually required.

Important Points

  • Understanding the causes, symptoms, and treatment of hypothyroidism is crucial for pharmacists to provide effective patient care.
  • Pharmacists play a vital role in:
    • Dispensing levothyroxine and ensuring patients understand its proper administration and potential interactions.
    • Educating patients on the importance of medication adherence and regular monitoring.

References

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