Selective venous catheterisation and radioimmunoassay of parathyroid hormone in the diagnosis and localisation of parathyroid tumours

Large Vein Sampling for Intact Parathyroid Hormone in Preoperative Localization of Enlarged Parathyroid Glands

Unilateral neck exploration for primary hyperparathyroidism (pHPT) of old and high risk patients can be safely performed under local anesthesia, provided there is a correct preoperative side localization of the enlarged parathyroid gland. We performed large vein sampling and measured intact parathyroid hormones (PTH) with a new, highly sensitive immunoradiometric assay. The method was used before operation in 20 patients with pHPT. A unilateral positive gradient of serum PTH levels was obtained in 15 patients. At surgery, 13 of these (87%) proved to be correct, i.e., the adenoma was localized on the same side. Thus, the technique correctly lateralized the parathyroid adenoma in 65% of the patients. We conclude that large vein sampling with measurement of intact PTH is a potentially useful investigation for preoperative side localization of parathyroid adenomas in pHPT patients scheduled for unilateral surgery under local anesthesia. However, prior to routine bilateral neck exploration large vein sampling is not justified.

The use of ultrasound in the localisation of parathyroid glands in parathyroid disorders

Eleven patients with clinical and biochemical evidence of primary hyperparathyroidism were studied with ultrasonography. In nine patients who were treated surgically, four had predictive ultrasound scans (44% consistency). There was no correlation between the transverse diameters of the glands, as measured from the scans, and either the pathologist's measurements or the mean protein-corrected serum calcium and parathormone (PTH) levels. The investigation failed to identify the only patient with parathyroid hyperplasia. The difficulties encountered and the reasons for the high number of both false positive and false negative scans are discussed. Five patients with parathyroid disorders associated with hyperplasia were also studied and in four patients the enlarged glands were identified. A variation in size between the glands in each patient was noted. No correlation between the total of the transverse diameters and either the protein-corrected serum calcium or PTH levels was found. Reduction in size of the glands in one patient occurred over a 12-month period on treatment and a role for ultrasonography in the follow-up of patients with secondary hyperparathyroidism is discussed.

Impact of sonography on surgery for primary hyperparathyroidism

The impact of preoperative sonographic localization of enlarged parathyroid glands was evaluated from the standpoint of operative time and complication rates. There was a reduction in the average time from 135 minutes when findings were false-negative to 111 minutes when findings were positive. The rate of complication was not changed by accurate preoperative localization. When the operative goal is to find all parathyroid glands in every patient, the value of preoperative localization of parathyroid tumors by any current method is slight. Should operative policy favor a search for only one enlarged and one normal gland, or should methods improve to the point that even normal parathyroid glands can be located reliably, noninvasive localization should prove to be useful, safe, and cost-effective, even when it is carried out before initial operation.

Multiple sampling for parathyroid hormone by subclavian approach

Selective venous catheterization with parathyroid hormone assay is a valuable procedure in the diagnosis and treatment of parathyroid tumors. The multiple sampling via the femoral vein is sometimes frustratingly uncertain and time consuming. The technique herein described is simpler, quicker, and less hazardous. It is accomplished via the subclavian approach, a relatively easier anatomic way, and utilizes a short single-curve catheter that gives a high degree of torsion control.

[Immunoreactive parathyroid hormone in samples from thyroid veins (author's transl)]

Blood samples were obtained from 16 patients with primary or secondary hyperparathyroidism by selectively catheterising cervical and thyroid veins. Immunoreactive parathyroid hormone was measured with two aminoterminal (anti-N)- and three carboxyl-terminal (anti-C)-specific antisera. Two anti-C sera and one anti-N serum were useful in localising the parathyroid tumors. In addition, the parathyroid hormone fragments were separated by gelfiltration and the immunoreactivity in the effluent was estimated with anti-N and anti-C sera. The results suggest that the usefulness of antisera for parathyroid tissue localisation is determined by their affinity for the intact hormone, regardless of their anti-N or anti-C qualities.

Selective catheterization of the thyroid veins for preoperative localization of parathyroid tumours

Samples obtained from the thyroid veins as well as from the great veins of the neck of 35 patients with primary hyperparathyroidism were assayed for parathyroid hormone. The overall distribution of the hormone was used to predict the location of the parathyroid tumour. In 27 patients the site of the adenoma was correctly predicted, and in a further 4 the side of the neck in which the tumour was to be found was forecast correctly; in only 4 patients was the technique unsuccessful. Thus, useful information was obtained in 31 of the 35 patients studied (88 per cent). Preoperative localization of parathyroid tumours in this way is of greater value than merely sampling large veins alone, particularly when there has been previous exploratory surgery.

Iatrogenic osteomalacia and myopathy due to phosphate depletion

In a patient receiving regular dialysis prolonged hypophosphataemia due to aluminium hydroxide therapy resulted in osteomalacia and severe proximal myopathy. Both osteomalacia and myopathy responded to correction of hypophosphataemia without vitamin D therapy.