Author Archive

Adrenal Medullary Hyperfunction

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Adrenal Medullary Hyperfunction

The adrenal medulla symthesizes the catecholamines norepinephrine, epinephrine, and do from the amino acid tyrosine. Norepinephrine, the major catecholamine produced by the adrenal medulla, has predominantly a-agonist actions, causing vasoconstriction. Epinephrine acts primarily on the B receptors, having positive inotropic and chronotropic effects on the heart, causing peripheral vasodilation, and increasing plasma glucose concentrations in…

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Adrenal Insufficiency

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Adrenal Insufficiency

Glucocorticoid insufficiency can be either primary, resulting from the destruction or dysfunction of the adrenal cortex, or secondary, resulting from ACTH hyposecrrtion. Autoimmune destruction of the adrenal glands(Addison’s disease) is the most common cause of primary adrenal insufficiency in the industrialized world, accounting for about 65% of cases. Both glucocorticoid and mineralocorticoid secretion are diminished…

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GROWTH HORMONE

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GROWTH HORMONE

GH is a 191-amino acid peptide with a molecular weight of 22,000 d. Secretion is stimulated by the 44-amino acid hypothalamic growth hormone-releasing hormone(GHRH) inhibited by the h thalamic tetradecapeptide somatostatin. These hypothalamic factors bind to pituitary somatotroph cells and regulate GH secretion. binds to receptors in the liver and induces insulin-like growth factor i(IGF-1),…

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Thyrotoxicosis Factitia

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Thyrotoxicosis Factitia

Thyrotoxicosis factitia presents as typical features of thyrotoxicosis from ingestion of excessive amounts of thyroxine, often in an attempt to lose weight. Serum T3 and T4 levels are elevated, and TSH is suppressed, as is the serum thyroglobulin concentration. Radioactive iodine uptake is absent. Patients may require psychotherapy. Struma ovarii occurs when an ovarian teratoma…

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Chronic Lymphocytic Leukemia

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Chronic Lymphocytic Leukemia

B-cell CLL is malignant disorder of lymphocytes characterized by expansion and accumulation of small lymphocytes of B-cell origin. CLL is essentially identical to B-cell small lymphocytic lymphoma in the REAL and WF classifications. CLL is the most common form of in the States and affects twice as many men as women. Although it can occur…

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TESTS OF SERUM THYROID HORMONE LEVELS

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TESTS OF SERUM THYROID HORMONE LEVELS

Total serum T4 and T3 measure the total amount of hormone bound to thyroid-binding proteins by radioimmunoassay. Total T4 and total Ta levels are elevated in Increase hyperthyroidism and low in hypothyroidism. Increase in TBG(as with pregnancy or estrogen therapy increases the total T4 and T3 measured in the absence of hyperthyroidism. Similarly, T and…

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GONADOTROPINS (LH AND FSH)

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GONADOTROPINS (LH AND FSH)

Gonadotroph secretion is regulated by hypothalamic gonadotropin-releasing hormone(GnRH), a 10-amino acid peptide secreted in a pulsatile manner, and feedback inhibition is regulated by gonadal steroids(estrogen and testosterone) and peptides(inhibin and activin) Basal LH and FSH are secreted in a pulsatile manner concordantly with the pulsatile release of GnRH. GnRH release determines the onset of puberty…

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BENIGN NEOPLASMS

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BENIGN NEOPLASMS

The category of benign neoplastic lesions includes hemangioma, hepatocellular, adenoma, nodular regenerative hyperplasia, focal nodular hyperplasia, and rare mesenchymal tumors(e.g., fibromas, lipomas, leiomyomas). Hemangiomas are the most common mesenchymal hepatic neoplasms, with a prevalence in the general population of 2% to 5%. They are usually located in the right lobe of the liver and are…

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Marfan’s Syndrome

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Marfan’s Syndrome

Marfan’s syndrome, long incorrectly thought secondary to a collagen abnormality, is caused by abnormalities of the ubiquitous extracellular protein fibrillin I. This cysteine-rich, 350-kd protein forms de bonded agcreates and, with, other proteins, generates microfibrils at are abundant in the periosteum, aorta, muscles, and tendons. Microfibrils appear to form the skeleton on which elastin disposition…

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PORPHYRIA CUTANEA TARDA

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PORPHYRIA CUTANEA TARDA

Several thousand cases of porphyria cutanea tarda(PCT) have been identified, but accurate prevalence figures are not available. The affected enzyme is uroporphyrinogen decarboxylase. The major porphyrins accumulating in plasma are uroporphyrin which is behind the partial enzymatic block, and 7- carboxylate porphyrin, the first product of the enzyme’s sequential action on uroporphyrin. Uroporphyrinogen and 7-carboxylate…

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