Catabolism, glucocorticoids causing

Catabolic effects As noted above, glucocorticoids cause muscle protein catabolism. In addition, lymphoid and connective tissue, fat, and skin undergo wasting under the influence of high concentrations of these steroids. Catabolic effects on bone can lead to osteoporosis. In children, growth is inhibited. 

Insulin is a powerful anabolic hormone but it is unlikely that insulin deficiency causes skeletal muscle atrophy by direct action on muscle fibers (as opposed to neurogenic atrophy) except in chronic untreated cases. There is however a close parallel between the catabolic states induced by glucocorticoid excess and by insulin deficiency. Moreover, impaired insulin action is implicated in other endocrine myopathies as a contributory cause of muscle wasting. Both acromegaly and thyrotoxicosis are associated with insulin resistance due to a postreceptor defect, and secondary hyperparathyroidism due to hypophosphatemia also gives rise to insulin insensitivity. 

The most significant impact of these drugs on rehabilitation is related to their side effects, especially those of the immunosuppressants. These drugs are typically used in high doses to produce immunosuppressive effects, which are often achieved at the expense of serious and toxic side effects. Many immunosuppressants, especially the glucocorticoids, exert catabolic effects on bone, muscle, and other tissues. Other immunosuppressants, such as cyclosporine and tacrolimus, are neurotoxic and may cause peripheral neuropathies and CNS-related problems in balance and posture. 

The answer is c. (Murray, pp 505—626. Scriver, pp 4029—4240. Sack, pp 121-138. Wilson, pp 287-320.) Vasopressin, which is also called antidiuretic hormone, increases the permeability of the collecting ducts and distal convoluted tubules of the kidney and thus allows passage of water. Like the mineralocorticoid aldosterone, vasopressin results in an expansion of blood volume. However, the mode of action of aldosterone is different it causes sodium reabsorption, not water reabsorption. Sodium reabsorption indirectly leads to increased plasma osmolality and thus water retention in the blood. Cortisol is a glucocorticoid that potentiates catabolic metabolism chronically. Epinephrine stimulates catabolic metabolism acutely. Insulin acutely favors anabolic metabolism, in large part by allowing glucose and amino acid transport into cells. 

E. Glucocorticoids The glucocorticoids have several effects already referred to (eg, protein catabolism see Chapter 39) that inhibit bone mineral maintenance. As a result, chronic systemic use of these drugs is a common cause of osteoporosis in adults. However, these hormones are useful in the intermediate-term treatment of hypercalcemia. 

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