The importance of the unsuppressed glands in the study of intact parathyroid hormone disappearance after parathyroid adenomectomy.

BACKGROUND: In the usual techniques for intraoperative intact parathyroid hormone (iPTH) monitoring for primary hyperparathyroidism, the normal glands are implicitly considered suppressed. On the contrary, we believe, as do other researchers, that they are not totally suppressed. METHODS: For this reason, we considered the introduction of an infusion from the unsuppressed normal glands (UNG), described by an influx constant (IC (pg/ml per min)), into the formulation of a two-compartment model. For the blood compartment, we have: C(t)=A.exp(-at)+B.exp(-bt)+EV, where A+B+EV=iPTH concentration at zero time (clamping), EV (equilibrium value)=IC/k, 'a' and 'b' are reciprocals of the time constants of the two exponentials and k=rate constant of elimination from the blood. The experimental data were obtained using an IRMA standard method, collecting samples in 20 patients, during and following adenomectomy. RESULTS: In spite of the variability among the patients, all fits were very good, thus confirming the importance of the UNG contribution to the shaping of the disappearance curve. For this reason, the relationship between the constant infusion from the UNG and the basal iPTH level at the induction of anaesthesia (BV), was studied. CONCLUSIONS: The existence of a negative correlation, together with the determination of a regression curve (IC=6.5BV), not only confirmed our assumptions, but also revealed the theoretical possibility of a priori knowledge of the iPTH contribution from the UNG. Hence, there is a theoretical possibility of discriminating between this contribution and that of the remaining (if any) affected gland(s).

[A new computerized electrocardiographic method of the study of the QRS complex in the diagnosis of myocardial ischemia (preliminary results)]. / Nuovo metodo elettrocardiografico computerizzato per lo studio del complesso QRS nella diagnosi di ischemia miocardica (risultati preliminari).

Based on the premise that the QRS complex is also involved in reversible ischemia, we designed a computerized electrocardiographic method, that we have named Ventricular Ischemic Site Analysis (VISA). This method compares mean resting QRS to the QRS complex recorded during exercise or pharmacologic stress. The effect of ischemia on the electrical process of myocardial depolarization can be seen as a smaller slope in the QR and/or RS segment of the QRS signal, thus causing a local change in shape of the QRS. This method makes it possible to evaluate both the maximum entity of the change in shape and the time at which this occurs with reference to the beginning of the cycle. The VISA test was compared to SPECT and to the normal ECG stress test on a group of 53 patients who underwent a SPECT 99mTc-Sestamibi for suspected myocardial ischemia. Among the 39 patients confirmed as ischemic, the VISA test was positive in 37, while the ischemic alterations of the ST-T segment were observed in only 10 patients. According to this study, the sensitivity of the VISA test is comparable to the levels seen in SPECT. Moreover, this method demonstrates a trend towards localization of the ischemia in posterior or lateral sites when the shape change in localized in RS segment, and in anterior or infero-apical sites when the change is in QR segment. In addition to increasing sensitivity with respect to normal ECG stress tests, this method may also represent a new field of application for the ECG stress test, offering the possibility of localizing ischemic areas via simple computerized electrocardiography.

A controversial problem: is there a relationship between parathyroid hormone level and parathyroid size in primary hyperparathyroidism?

The current study was undertaken with the aim of studying the relationship between parathyroid hormone and hyperfunctioning parathyroids by a sophisticated method of analysis. Our clinical study included 25 patients undergoing surgery for primary hyperparathyroidism. The measurement of basal circulating intact PTH (pg/ml) and the volume (mm3) of the removed gland(s) were recorded. It was essential for the distribution of the sample values to be normal before Pearson's correlation and regression analysis were performed. The Kolmogorov-Smirnov test showed sufficient sample data agreement (p > 20%) with normal distribution after their transformation into natural logarithm (ln) and so statistical analysis was performed utilizing ln transformed data. The regression line between basal ln of iPTH levels (x) and ln of tumor volume (y) was highly significant (y = 2.3828 + 1.0424 x, r = .72504, p < .0001). In our opinion, the above is a correct statistical procedure with reliable results.