Endocrine

HYPOTHYROIDISM

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objectives

What causes hypothyroidism What are the clinical signs? How is it diagnosed? Can it be treated?

Hypothyroidism

Failure of the thyroid gland to produce adequate amounts of hormone1-Primary2-Secondary – decreased secretion of TSH from pituitary

Thyroid gland normally releases thyroxine (T4) daily and small amounts of T3 T4 half-life 7-10 days T4 (prohormone) converted to T3 in peripheral tissues Generally, thyroid disease is more common in females

The prevalence of primary hypothyroidism is 1:100, The female:male ratio is approximately 6:1

HASHIMOTO'S THYROIDITIS

The nomenclature of autoimmune hypothyroidism. Some authorities reserve the term 'Hashimoto's thyroiditis' for patients with positive thyroid peroxidase autoantibodies and a firm goitre who may be hypothyroid, and use the term 'spontaneous atrophic hypothyroidism' for hypothyroid patients without a goitre in whom TSH receptor-blocking antibodies may be more important

Clinical features

A consequence of prolonged hypothyroidism is the infiltration of many body tissues by the mucopolysaccharides, hyaluronic acid and chondroitin sulphate, resulting in 1- a low-pitched voice, 2- poor hearing, 3- slurred speech due to a large tongue,



4- compression of the median nerve at the wrist (carpal tunnel syndrome). 5- Infiltration of the dermis gives rise to non-pitting oedema (i.e. myxoedema) which is most marked in the skin of the hands, feet. 6-periorbital puffiness is often striking and, when combined with facial pallor due to vasoconstriction and anaemia, 7- a lemon-yellow skin due to carotenaemia,. 8-tiredness, weight gain.

Tiredness

Forgetfulness/Slower Thinking
Moodiness/ Irritability
Depression
Inability to Concentrate
Thinning Hair/Hair Loss
Loss of Body Hair
Dry, Patchy Skin
Weight Gain
Cold Intolerance
Elevated Cholesterol
Family History of Thyroid Disease or Diabetes
Muscle Weakness/Cramps
Constipation
Infertility
Menstrual Irregularities/Heavy Period
Slower Heartbeat
Difficulty Swallowing
Persistent Dry or Sore Throat
Hoarseness/Deepening of Voice
Enlarged Thyroid (Goiter)
Puffy Eyes
Clinical Features of Hypothyroidism

INVESTIGATION OF PRIMARY HYPOTHYROIDISM

3-anaemia, which is usually normochromic and normocytic in type but may be macrocytic (sometimes this is due to associated pernicious anaemia) or microcytic (in women, due to menorrhagia) • 4-increased creatine kinase levels • 5- hypercholesterolaemia • 6-hyponatraemia due to an increase in ADH and impaired free water clearance.

Managment

Hypothyroidism should be treated with thyroxin it is available in 25 ,50, 100microgram tablests the dose should be started50 mg then should be increased to 100mg after 3wks &after another 3wks should raised to 150 mg &should be given single dose .


If the patient had ischemic heart disease or elderaly the dose should be reduse to 25 mg daily . Serum TSH should be measured 8 weeks after starting the treatment to check whether the dose needs to be increased and should be measured annually in patients on established treatment to ensure continuing compliance

Myxoedema coma

Myxoedema coma is a medical emergency and treatment must begin before biochemical confirmation of the diagnosis. Thyroxine is not usually available for parenteral use so triiodothyronine is given as an intravenous bolus of 20 μg followed by 20 μg 8-hourly until there is sustained clinical improvement.