Diagnosis of parathyroid cysts: parathormone assay in puncture fluid

OBJECTIVE: Determine a means of establishing the diagnosis of parathyroid c ysts preoperatively. PATIENTS AND METHODS: Classically, crystal-clear watery fluid removed by fi ne-needle aspiration:bf a suspected thyroid mass raises the suspicion of a parathyroid cist. Immunoradiometric assay of parathyroid hormone level in t he fluid may give the diagnosis sparing unnecessary surgery. RESULTS: Over the last 5 years, among the 12 patients presenting a suspecte d thyroid cyst containing a crystal-clear fluid, we were able to diagnose 3 cases of parathyroid cysts due to the considerable elevation of parathyroi d hormone in the puncture fluid. None of these patients had hyperparathyroi dism. In patients with a thyroid cyst, parathyroid hormone level in the pun cture fluid was nil. CONCLUSION: The parathyroid nature of cervical cysts containing crystal-cle ar fluid can be established by assaying parathyroid hormone in the puncture fluid. Non-functional parathyroid cysts may be treated by repeated aspirat ion. Serum calcium level must be checked regularly to detect potential hype rparathryoidism.