[Diagnostic tests in parathyroid diseases].
The diagnosis of primary hyperparathyroidism (PHP) depends increasingly on laboratory tests, since the majority of patients are elderly people without typical symptoms. A mean plasma calcium level close to the upper normal limit serves to diagnose hypercalcemia. To rule out malignant disease, the most common cause of hypercalcemia, measurement of plasma PTH is the most appropriate test. Determination of blood phosphorus, chloride, and alkaline phosphatase, and of urinary calcium and phosphorus, contribute to the investigation of the metabolic effects of the given disease but are not very useful for causal diagnosis. Urinary and nephrogenous cyclic AMP reflect PTH secretion but can be elevated in paraneoplastic hypercalcemia. Diagnosis of subtle forms of PHP by dynamic tests is largely of scientific interest, since they do not necessarily need treatment. The diagnosis of hypoparathyroidism is primarily clinical. PTH measurements rarely distinguish normal from low values. In severe hypocalcemia of non-parathyroid origin, plasma PTH is elevated (except in hypomagnesemia). In borderline cases, measurement of urinary cyclic AMP or of plasma PTH after attempted stimulation by EDTA infusion is helpful, especially in distinguishing between subtle hypoparathyroidism and tetany induced by hyperventilation.
D000236:Adenoma / Q000175:diagnosis; D000469:Alkaline Phosphatase / Q000032:analysis; D002118:Calcium / Q000032:analysis; D002712:Chlorides / Q000032:analysis; D000242:Cyclic AMP / Q000652:urine; D006801:Humans; D006961:Hyperparathyroidism / Q000175:diagnosis*; D007011:Hypoparathyroidism / Q000175:diagnosis*; D010281:Parathyroid Hormone / Q000097:blood; D010282:Parathyroid Neoplasms / Q000175:diagnosis; D010758:Phosphorus / Q000032:analysis
D002712:Chlorides; D010281:Parathyroid Hormone; D010758:Phosphorus; D000242:Cyclic AMP; D000469:Alkaline Phosphatase; D002118:Calcium
Tests de diagnostic des maladies des parathyroïdes.