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Jul22
THYROID HORMONE STATUS IN ACUTE MYOCARDIAL INFARCTION
1.

The thyroid is one of the important endocrine glands in human being. It secretes hormones like thyroxine (T4), tri –iodothyroine (T3) and calcitonin. The relationship between the thyroid gland and various body functions was studied in 1827 (Werner & Ingbar). Perry in 1835 described the clinical manifestation of exophthalmic goiter. Its association with angina pectoris and congestive heart failure.
In peripheral tissues,T4 in mainly metabolized to form active hormone 3,5,3’ – triiodothyronine (T3) and inactive 3,3’,5’,- triiodothyronine (reverse T3) as per the demand of the body (Bitman et al, 1971 and Chopra et al 1978). Non – thyroidal acute and chronic illnesses are the major cause of disordered peripheral thyroid hormone metabolism often poses a major problem in interpreting thyroid function tests (Cavalieri and Repport. 1971) it is generally agreed that despite gross abnormality in circulating thyroid hormones, most of these ill patients are clinically euthyroid.
A wide variety of systemic illnesses like infarction. malignant disease, hepato –cellular failure, renal failure protein – calorie malnutrition, congestive heart failure are associated with decreased T3, elevated reverse T3(rT3) and decreased, normal or increased serum T4 concentration. (Burger et al 1976, Rosenthal and Cavelieri, 1979).
AMI, frequently fatal form of ischemic heart disease (IHD) results due to considerable jeopardisation of coronary blood flow, is one of the commonest systemic nonthyroidal illnesses where thyroid hormone economy in altered. But conflicting reports regarding thyroid status has been published in this condition. Supra normal value of T4 in AMI have been observed by Wierainga et al 1981, Vanhaelst et al 1976 and Kirkeby et al 1984.
On the other hand decreased T3 and T4 in face of elevated reverse T3 has been observed by Kaplan 1977, Westgreen et al 1977 and Marek et al 1980.
Normal T4 with unequivocal elevation of rT3 and significant reduction of T3 also have been found by Smith et al 1978, Fabre et al 1980 and Lada et al 1981.
It has been also observed that magnitude of lowering of T3 and T4 correlates well with the severity of illnesses and survival. (Larty et al 1975 and Kaptain et al 1978, 1982)
The outcome of AMI depends of many factor like degree of myocardial damage, associated arrythmias, hypotension and shock.(Hurst 1982). How ever, commonly sudden death occurs in those cases with or without complication.
It is the intended:-
1. To study the thyroid hormone levels in AMI through out the illness.
2. To correlate the changes of thyroid hormone levels with the severity of these conditions.
3. To correlate the thyroid hormone levels with outcome that is recovery or death.
The thyroid is the largest endocrine gland. In the past it escaped the notice of most of the investigators owing to its inconspicuous shape and position. Vasalius in 1543 described it in details while Whartsen in 1656 named the organ “The Thyroid”
The relationship between the thyroid gland and various body function was studied in 1827. Parry in 1835 described the clinical manifestations of exophthalmic goiter and its associations with angina pectoris and congestive heart failure. In 1915 Kendall found the L – thyroxine (T4) from thyroid tissue whereas Pitterson and Gross found tri – iodothyronine in plasma and thyroid in 1954. ( Werner and lngbars H.,1971). Several studies have shown the relationship of the thyroid hormones with the thyroid and non thyroidal illnesses ( Herrison, Mc Donald, Hoffman, and Pool). Levy in 1971 demonstrated increased adrenergic activities in hyperthyroidism.
The Thyroid is highly vascular and comprises the follicles which contain proteinacious colloid. The colloid contains glycoprotein, thyroglobulin (TG) within which thyroxine(T4) and Tri – iodothyronine (T3) are formed and stored. Moreover, thyroid contains parafollicular cells which secrets calcitonim. (Copp & Co- workers in 1962).


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