• Hypothyroidism is a state of deficient function of the thyroid gland i.e. deficient secretion of thyroid hor­mones.
  • In hypothyroidism normal thyroid hormone levels are maintained by a rise in TSH. This is called subclinical hypothyroidism.
  • Later free T4 level falls and TSH levels rise further. This is the stage of clinical hypothyroidism when fea­tures of deficiency of thyroid hormones become mani­fest.
  • Sub-clinical hypothyroidism is found in 10% of women over the age of 60 years.

HYPOTHYROIDISM Causes Diagnosis and Treatment

Types of hypothyroidism

Primary hypothyroidism

  • is a primary deficiency of thyroid hormones due to hyposecretion by the thy­roid gland.
  • A normal TSH level means that the patient cannot have primary hypothyroidism. In primary hypothy­roidism i. e. disease of thyroid responsible for hypothy­roidism, the TSH level rises. As a screening test TSH estimation is very good.
  • T4 cannot be used as a screening test because it can­not detect sub clinical hypothyroidism (normal T4 with elevated TSH).

Secondary hypothyroidism

  •  is due to anterior pitu­itary hormone deficiencies.
  • Isolated TSH deficiency is rare.
  • TSH levels may be normal, low or slightly increased in secondary hypothyroidism. Free T4 is low.

Signs and Symptoms of HYPOTHYROIDISM

  • History
    • Arthralgias
    • Carpal tunnel syndrome
    • Cold intolerance
    • Constipation
    • Decreased memory, concentration
    • Decreased sweating
    • Depression
    • Hearing impairment
    • Hoarseness
    • Menorrhagia
    • Modest weight gain (10 lb [4.5 kg])
    • Muscle cramps
    • Onset may be insidious, subtle
    • Paresthesias
    • Weakness, fatigue, lethargy
  • Physical Exam
    • Bradycardia
    • Coarsening or huskiness of voice
    • Delayed relaxation of deep-tendon reflexes
    • Dry, coarse skin
    • Dull facial expression
    • Hypothermia
    • Increased diastolic BP
    • Macroglossia
    • Periorbital puffiness
    • Reduced body and scalp hair
    • Reduced systolic BP
    • Swelling of hands and feet (nonpitting)

Causes of hypothyroidism:

  • 1. Autoimmune hypothyroidism (Hashimoto’s thyroiditis)
  • 2. Iodine deficiency
  • 3. Amiodarone and lithium
  • 4. Antithyroid drugs
  • 5. Iodine excess
  • 6. Congenital hypothyroidism
  • 7. After thyroidectomy or irradiation
  • 8. Thyroiditis
  • 9. Hypopituitarism
  • 10. Hypothalamic diseases.

Clinical Manifestations of Hypothyroidism

  • · Tiredness and weakness
  • · Dry skin
  • · Feeling of cold
  • · Hair loss
  • · Difficulty in concentration and poor memory
  • · Constipation, weight gain, poor appetite
Hoarseness of voice
Edema – Non-pitting
Delayed tendon reflex
Carpal tunnel syndrome
Pleural effusion
Pericardial effusion.


HYPOTHYROIDISM Associated Conditions

  • Anemia
  • Depression
  • DM
  • Down syndrome
  • Hypercholesterolemia
  • Hyponatremia
  • Hypoparathyroidism
  • Idiopathic adrenocorticoid deficiency
  • Ischemic heart disease
  • Metabolic syndrome
  • Mitral valve prolapse
  • Myasthenia gravis
  • Rapid-cycling bipolar disorder
  • Vitiligo

Lab diagnosis

  • · TSH estimation (elevated)
  • · T4 (Low)
  • · TPO antibodies (thyroid peroxidase)
  • · FNA (fine needle aspiration) biopsy
  • · Elevated cholesterol and triglycerides
  • · Anaemia.


  • Levothyroxine 100 – 150 IJgjday.
  • Lower doses may be given to patients of Grave’s disease who need replacement after treatment of hyperthyroidism.
  • Dose is adjusted to keep the TSH levels in the lower range. TSH is measured 2 months after start of treatment.
  • There is full relief after 3 – 6 months, after nor­mal TSH levels are regained.
  • Levothyroxine is increased in doses of 25 IJg only. Overtreatment with T4 (thyroxine) results in re­duced bone density and atrial fibrillation.
  • Once TSH levels are stable, then TSH may be measured annually only.
  • T4 has a long half life of 7 days, therefore, any missed doses can be made up by taking 2-3 tab­lets at once.
  • Pregnant women should be made euthyroid. Patients should be euthyroid before surgery. Eld­erly patients require less thyroxine.


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