Topic: Endocrine system: Mechanism of action of hormones
Question: A 40- year old female patient reported that she was feeling very weak. Her arms and
legs were thin but abdomen, upper back and face were full with deposition of fat. She had also noticed that minor injuries were resulting in bruises and taking a long time to heal. Reddish purple striations were seen in the skin of her abdomen. Her blood pressure was180/100 mmHg, pulse rate was 99/min.
a) Identify the condition.
b) Discuss the physiological basis for the above condition
c) Discuss the physiological and pharmacological actions of glucocorticoids
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a) The condition described is Cushing’s syndrome due to the symptoms of central obesity, thin limbs, easy bruising, striae, hypertension and proximal muscle weakness.
b) Physiological basis:
– Cushing’s syndrome is caused by chronic excess of glucocorticoids like cortisol.
– Increased glucocorticoids cause deposition of fat in characteristic distribution like face, neck, upper back and abdomen resulting in central obesity and thin limbs.
– Glucocorticoids cause protein catabolism leading to proximal myopathy and muscle wasting in limbs.
– They impair collagen synthesis causing easy bruising and poor wound healing.
– They also have mineralocorticoid effects leading to hypertension and hypokalemia.
c) Physiological actions of glucocorticoids:
– Increasing blood glucose by promoting gluconeogenesis, glycogen synthesis and insulin resistance.
– Anti-inflammatory effects by inhibiting leukocyte activation and cytokine production.
– Immunosuppressive actions by reducing antibody and lymphocyte production.
– Catabolic effects on protein, causing muscle wasting.
– Retention of sodium and water causing edema and hypertension.
Pharmacological uses:
– Anti-inflammatory drugs like prednisolone to treat inflammatory and autoimmune conditions.
– Immunosuppressants like dexamethasone used in organ transplants.
– Replacement therapy in adrenal insufficiency like Addison’s disease.
– Treatment for certain cancers like lymphoma, leukemia.
– Temporarily helping COPD, asthma exacerbations.
