2nd case: a 25 year old young woman has recurrent episodes of headache and sweating. Her mother had renal calculi and died after having a neck mass. The physical examination reveals a thyroid nodule but no clinical sign of thyrotoxicosis. Before performing thyroid surgery , the surgeon should order ?
- measurement of thyroid hormones
- serial determinations of serum calcium, phosphorous protein and alkaline phosphatase
- 24 hours urine test for 5 HIAA excretion
- Serial 24 hours test for catecholamines,metanephrines and vanillylmandelic acid excretion
Answer : d . pheochromocytoma must be excluded by measurement of urinary catecholamines levels in all cases before embarking upon thyroid surgery to avoid the potential hazards of this condition .
Assays employed for diagnosis of pheochromocytoma include those for :
- vanillyl mandelic acid
- metanephrines
- free catecholamines
- the patient in question is a case of inherited MEN 2a syndromes . the presence of headache and sweating in a patient with thyroid nodule warrants prompt investigation for a possible pheochromocytoma as part of MEN 2 syndrome , more so in a patient with a positive familiy history ( as suggested by presence of renal calculi and thyroid nodule in mother )
- pheochromocytoma secrete large amounts of catecholamines , the secretion of which is further increased during surgery . this may result in large swings in blood pressure and arrythmias, and increases the risk of surgical mortality. Stable alpha adrenergic blockage is essential before embarking on thyroid surgery .
--- the option c is concerned with the diagnosis of carcinoid syndrome .
--- serum calcium and phosphorous alkaline phosphatase may aid in the diagnosis of hyperparathyroidism a part of MEN 2a but again offer no specific advantage to surgeons prior to surgery of thyroid .
1 comment:
Very interesting and informative! :-) Thanks for posting :-)
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