Identification of the parathyroids may present some difficulties at the time of thyroid surgery, or during neck explorations for parathyroid tumors. Fat, lymph nodes, and thyroid adenomas have been confused with parathyroid tissue.
Toluidine blue, a phenothiazine dye, has been used in cases of cyanide and carbon monoxide poisoning and in some types of bleeding because of its antagonistic action to heparin. Recently, it has been shown to stain oral cancer.1
Moe, in 1964, attempted to stain the corpus of the stomach in animals in which toluidine blue was injected intravenously and found that the pancreas and parathyroids stained as well. Klopper and Moe2 reported a more detailed investigation of parathyroid staining in 1966 in which toluidine blue was injected into the femoral veins of dogs (10 mg/kg of body weight over a 10-to-20-minute period). Oral administration had been shown to be ineffectual. Good staining of the parathyroid