| ID | 62 |
|---|---|
| Name | HYPOTHYROIDISM |
| Cause | |
| Signs Symptoms | |
| Diagnosis | Diagnosis:2 1. Quantity of total serum thyroxine, T3, T4 & TSH. (In primary hypothyroidism serum T4 is low and TSH is elevated; T3 is insignificant since they do not discriminate reliably between euthyrodism and hypothyroidism.) 2. Radioactive iodine uptake. 3. Radiographs of the epiphyses in children or ossification centres in the wrist or heel in infants. 4. Serum electrolyte- hyponatraemia, due to an increase in ADH and impaired free water clearance. 5. Hb estimation & film study- anemia, which is usually normochromic and normocytic, but may be macrocytic (due to associated pernicious anemia) or microcytic (in female, due to menorrhagia). 6. E.C.G shows slow rate and low voltage with flattened and inverted T wave. |
| Investigations | |
| Management | |
| Introduction | Hypothyroidism may be due to causes within the thyroid gland itself (primary) or less commonly, to failure of TSH production following pituitary or hypothalamic disease (secondary). Females are affected approximately six times more frequently than males. |
| History | |
| Etiology | |
| Clinical Features | Clinical features: Primary hypothyroidism (in adult)- General - Tiredness, somnolence, weight gain, cold intolerance, hoarseness of voice, goitre. Cardiorespiratory- Bradycardia, hypertension, angina, cardiac failure, xanthelasma, pericardial and pleural effusion. Neuromuscular - Aches and pains, muscle stiffness, delayed relaxation of tendon reflexes, carplal tunnel syndrome, deafness, depression, psychosis, cerebellar ataxia, myotonia. Haematological - Macrocytosis, anemia [iron deficiency (premenopausal women), normochromic, pernicious.] Dermatological - Dry flaky skin and hair, alopecia, purplish lips and malar flush, carotenaemia, vitiligo, erythema ab igne (granny’s tartan), myxoedema. Reproductive - Menorrhagia, infertility, galactorrhoea, impotence. Gastrointestinal -Constipation, Ileus, ascites. In children- A deterioration in performance at school, lack of interest in games and an arrest or slowing of growth. In Infant - The diagnostic features are failure to achieve the normal milestones of development, constipation, poor feeding and a characteristic cry. In advanced cases the features of cretinism will be obvious e.g a coarse facies with a broad flat nose, thick lips, a large protruded tongue, pot belly with umbilical hernia. |
| Preventions | |
| Treatment | Treatment: Hypothyroidism is treated with thyroxine (levothyroxine i.e T4) as replacement therapy for whole life. Levothyroxine, in the body is converted enzyma-tically to T3, the most active thyroid hormone, that best meets the metabolic needs of the patient. Usually thyroxine is given as a single daily dose, as its plasma half-life is approximately 7 days & preferably before breakfast. 1. In uncomplicated adult cases- thyroxine, usual starting dose is 50ugm/day which is given for 3 weeks, then increased to 100ngm/day for a further 3 weeks and finally to a maintenance dose 100-150ugm/day. 2. In hypothyroid patients with ischaemic heart disease, thyroxine should be started with a low dose of 25ugm/day. Series of ECGs may be done for monitoring cardiac ischaemia; if no angina or not worsenning of condition, doses may be increased gradually at intervals of 3-4 wks. up to l00ugm daily Treatment for ischaemic heart disease should be given concomitantly, according to the advice of a cardiologist. 3. In infants and children start treatment with thyroxine 5-7.5ugm/kg body weight daily as a single dose. After 3 years of age the dose should be 3.5-5ugm/kg/day. Liothyronine (T3) having similar action to thyroxine, but more rapidly metabolised in the body. 20ugm of liothyronine is equivalent to l00ugm of thyroxine. Its action usually appears after a few hours of administration and disappears within 24 to 48 hours of discontinuation. It is preferable in severe hypothyroidism where a rapid response is desired.21 The dose of thyroxine should be adjusted to maintain serum TSH within the reference range. To achieve this, serum T4 often needs to be in the upper level of the normal range or even slightly high. For this, it is advised to measure thyroid functions every year once the dose of thyroxine is stabilised |
| Complications | |
| Prognosis | |
| Types | |
| Classification | Aetiological classification:2 Primary hypothyroidism: 1. Autoimmune a. Hashimotos thyroiditis b. Spontaneous atrophic hypothyroidism c. Graves’ disease with TSH receptor-blocking antibodies 2. latrogenic a. Radioactive iodine (131I) ablation b. Thyroidectomy (surgical treatment of thyrotoxicosis, over 90% of cases) c. Drugs d. Carbimazole, methimazole, propylthiouracil e. Amlodarone f. Lithium 3. Transient thyroiditis a. Subacute (de Quervain’s) thyroiditis b. Post-partum thyroiditis 4. Iodine deficiency, e.g. in mountainous regions 5. Congenital a. Dyshormonogenesis b. Thyroid aplasia 6. Infiltrative Amyloidosis, Riedel’s thyroiditis, sarcoidosis etc. Secondary hypothyroidism: 1. TSH deficiency due to pituitary disease, or 2. TSH deficiency due to hypothalamic disease. |
| Observation | |
| Pathology |
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