Effects of Premedication, Halothane-N<SUB>2</SUB>O Anesthesia and Surgery on Plasma LH Concentrations in Man

In the previous study a significant increase in plasma immunoreactive luteinizing hormone (LH) concentrations was found following thiopental-N₂O anesthesia alone.<BR>The present study was undertaken to investigate the effects of halothane anesthesia and surgery on human plasma LH concentrations in thirteen male patients (halothane group).<BR>In addition to this, to explore diurnal variations of plasma LH concentrations 10 male patients who received neither anesthesia nor operation were studied, and the effects of preanesthetic medications (premedicated group) were also studied in 11 men. No patients with hepatic, renal or endocrine dysfunction were included.<BR>Both patients of the premedicated group and the halothane group received 100 mg of pentobarbital p.o. at 6 : 30 A.M., 35 mg of pethidine and 0.5 mg of atropine i.m. at 7 : 00 A.M.<BR>In the halothane group, anesthesia was induced by inhalation of 1-2% of halothane with nitrous-oxide (4-6 l/min) and oxygen (2 l/min). Anesthesia was miantained with 0.5-1.2% of halothane, 50% of nitrous-oxide and oxygen at least 45 minutes before the beginning of surgery.<BR>Peripheral venous blood samples were obtained from the antecubital vein through an indwelling catheter, times : <BR>(1) 8 : 00, (2) 8 : 30, (3) 9 : 00, (4) 9 : 30, (5) 10 : 00, (6) 11 : 00, (7) 12 : 00 in the diurnal variation group : (1) 8 : 00, (2) 8 : 30, (3) 8 : 45, (4) 9 : 00, (5) 9 : 30, (6) 10 : 00, (7) 11 : 00, (8) 12 : 00 in the premedicated group : and (1) 8 : 00 just before anesthesia and (2) 15, 30, 45 min after induction of anesthesia but before surgery, (3) 15, 30 min, 1, 2 hours after the start of surgical operation (4) in the recovery room, (5) 8 : 00 on the first postoperative day, and (6) 8 : 00 on the 7th day postoperatively in halothane group.<BR>Plasma LH concentrations was determined by the double antibody radioimmunoassay.To avoid interassay error all plasma from each patient was included in the same assay, and the value of 10.7±1.6 (mean±S.D.) mIU/ml was obtained among 7 times interassay measurements. The variations of coefficience of accuracy is 6.8% for the value of 12.7 mIU/ml (n=10).<BR>The following results were obtained.<BR>1. In the halothane group, plasma LH concentrations increased significantly (p<0.05) by 36% of the control level (15.8±1.5 mIU/ml) 30 min after the induction of anesthesia alone. They formed a plateau of high level (20.2-21.2 mIU/ml) till 30 min after the start of surgery.<BR>2. They began to decrease to the control level of 15.6±1.5 mIU/ml 2 hours after the start of surgery, and the lowest level of 11.5±1.6 mIU/ml was observed on the 1st postoperative day.<BR>3. On the morning of 7th postoperative day, plasma LH concentrations returned to the preoperative levels.<BR>4. In the premedicated-group, plasma LH concentrations were decreased significantly but transiently (p<0.01) to 70% of the control level (14.1±3.5 mIU/ml) at 9 : 00. Thereafter they went up to the control level.<BR>5. No diurnal variations of the mean plasma LH concentration were observed during a period between 8 : 00 and 12 : 00. But, abrupt elevations of plasma LH concentration were recognized in several cases.<BR>The results obtained would imply that halothane anesthesia per se would cause a elevation in LH concentration in the human plasma. However, surgical intervention would have an inhibitory effect on them.