Surgery for primary hyperparathyroidism 1962-1996: indications and outcomes

OBJECTIVE

To examine changes over the past three decades in the indications for, and outcomes of, surgery for primary hyperparathyroidism.

DESIGN

Survey of a prospective hospital database.

SETTING

Royal North Shore Hospital (a tertiary referral and university teaching hospital), Sydney, New South Wales, January 1962 to December 1996.

PATIENTS

All 733 patients who underwent neck exploration for primary hyperparathyroidism.

RESULTS

The annual number of parathyroidectomies increased virtually exponentially, from a mean of two in 1962-1969 to 73 in 1996. In the 1960s and 1970s, the most common indication for surgery was the presence of renal calculi (58% and 43%, respectively), but in the 1980s there was a marked increase in presentation of asymptomatic disease after biochemical screening (19%). In the 1990s, low bone mineral density detected by osteodensitometry has become the most common indication for surgery (31%). After initial operation, 11 patients (2%) had persistent hypercalcaemia, with five of these cured by reoperation--an overall failure rate of 1%.

CONCLUSIONS

Surgery for primary hyperparathyroidism has become increasingly common, with low bone mineral density replacing renal calculi as the most common indication for surgery. Neck exploration in experienced hands results in an overall cure rate of 99%.

Diabetes mellitus

Elderly diabetic patients require education in dietary therapy, physical activity, and self-monitoring of glycaemic control. However, rather than tight control, treatment should aim for a simple regimen which will relieve symptoms without introducing complications of its own. It is important to be aware of possible interactions between hypoglycaemic agents and drugs given for other diseases.

Differential effects of estrogen, tamoxifen and the pure antiestrogen ICI 182,780 in human drug-resistant leukemia cell lines

ICI 182,780, a potent, new steroidal antiestrogen without apparent agonist activity, appears to be a potent modulator of the classic multidrug resistance (MDR) phenotype in the CEM/A7, CEM/VLB100 and K562/VIN100 MDR cell lines. This reagent had no effect on the respective parental CCRF-CEM and K562 cell lines. The use of 1.25 microM ICI 182,780 resulted in a 6- to 7-fold decrease in doxorubicin resistance in the CEM/A7 and CEM/VLB100 cell lines. A dose-response effect was observed at ICI 182,780 concentrations of up to 5 microM. As compared with tamoxifen (TAM), ICI 182,780 was 2 and 4 times more effective in the K562/VIN100 and CEM/A7 cell lines, respectively. ICI 182,780 at 0.625 microM increased [3H]-daunomycin uptake (P < 0.0001) as effectively as 5 microM TAM in the resistant CEM/A7 line. Drug-efflux studies showed that 5 microM ICI 182,780 significantly decreased drug efflux as compared with 5 microM TAM (P < 0.0001). Estradiol (EST) at 10 microM increased doxorubicin resistance by 1.2-1.3 times in the CEM/A7 and CEM/VLB100 cell lines and significantly decreased drug accumulation (P = 0.002) and retention (P < 0.001) in the CEM/A7 cell line. However, the addition of 10 microM EST to 1-2 microM ICI 182,780 did not inhibit the ability of ICI 182,780 to modulate doxorubicin resistance in the two resistant cell lines. Using reverse-phase high-performance liquid chromatography (HPLC) to measure lipophilicity, we found no apparent association between the ability of ICI 182,780, TAM or EST to modulate resistance and their relative hydrophobicity.

Combined use of cyclosporin A and verapamil in modulating multidrug resistance in human leukemia cell lines

This study describes the synergistic interaction of two biochemical modulators, cyclosporin A (CyA) and verapamil (Vp), in multidrug-resistant cells, the highly resistant and moderately resistant variants (CEM/VLB 1000 and CEM/VLB 100) of the parental drug-sensitive T-cell leukemia cell line CEM/CCRF. In the absence of either modulator, the 50% inhibitory concentration for Adriamycin in these cell lines was 270 +/- 10.6 (SD) micrograms/ml, 96 +/- 8.5 micrograms/ml, and 1.5 +/- 0.1 micrograms/ml, respectively. CyA and Vp dramatically reduced multidrug resistance in CEM/VLB 100 and CEM/VLB 1000 in a dose-dependent manner but had no effect on the sensitivity of the parental line to Adriamycin. At a CyA concentration of 8.3 mumol (10 micrograms/ml), the 50% inhibitory concentration of Adriamycin of CEM/VLB 1000 and CEM/VLB 100 fell to 5.9 +/- 0.9 micrograms/ml and 3.3 +/- 0.6 micrograms/ml, respectively. Similarly at a Vp concentration of 10 mumol the 50% inhibitory concentration of Adriamycin of CEM/VLB 1000 and CEM/VLB 100 fell to 23.7 +/- 3.7 micrograms/ml and 5.7 +/- 0.2 micrograms/ml, respectively. More importantly, CyA and Vp showed significant synergism when tested in combination in the moderately resistant line at concentrations normally seen after the clinical administration of these modulators. Synergy was also present when both drugs were tested in the highly resistant variant. These data indicate the need for in vivo studies, given the potential clinical importance of these observations.

Effect of cyclosporin and verapamil on the cellular kinetics of daunorubicin

Both cyclosporin and verapamil modulate the multidrug-resistant (MDR) phenotype in the classical MDR cell lines, CEM/VLB100 and CEM/VLB1000. Initial studies demonstrated a significant reduction in daunorubicin accumulation in the two resistant lines compared with the drug-sensitive parent line CEM/CCRF. Both cyclosporin and verapamil increased drug accumulation in the resistant lines. This effect was dose-dependent although a plateau occurred in CEM/VLB100 cells at concentrations of cyclosporin exceeding 4.2 mumol/l. Cyclosporin 4.2 mumol/l and verapamil 10 mumol/l significantly increased daunorubicin uptake and reduced drug efflux in the CEM/VLB100 and CEM/VLB1000 lines. At low clinical concentrations of cyclosporin (0.8-1.6 mumol/l and verapamil (1-2 mumol/l), there was a synergistic increase in drug accumulation in the two resistant cell lines (P less than 0.007). These data suggest that cyclosporin modulates the classical MDR phenotype by altering the cellular kinetics of daunorubicin. The in vitro synergistic action of cyclosporin and verapamil could be interesting clinically.

Metabolism of porcine, human and salmon calcitonin in the rat

Whereas the liver is the major site of accumulation of 125I-labelled porcine calcitonin soon after injection in the rat, both human and salmon calcitonin were rapidly taken up in rat kidney, with relatively insignificant amounts found in the liver.

In-vitro studies of degradation of 125I-labelled calcitonins showed that human calcitonin was readily degraded by most rat tissues but the major activity was found in a kidney microsomal fraction, whereas the liver supernatant was most active towards pig calcitonin. Salmon calcitonin was resistant to breakdown by all tissues and fractions except the kidney microsomal fraction, which rapidly degraded it to trichloroacetic acid-soluble fragments. Liver homogenates from a number of mammalian and non-mammalian species degraded pig calcitonin but had little effect on salmon calcitonin.

The results show that the kidney is the most important organ in the metabolism of human and salmon calcitonin in the rat, while confirming that the liver is mainly responsible for the metabolism of porcine calcitonin.

Tissue distribution of calcitonin in the rat: comparison with parathyroid hormone

When [125I]calcitonin was injected intravenously into rats the major site of accumulation of radioactivity was the liver, whereas [125I]parathyroid hormone was localized chiefly in the kidney.

The distribution of [125I]bovine serum albumin and of Na [125I] was studied for comparison. Although most of the radioactivity of [125I]calcitonin was found in the soluble fractions of liver and kidney, significant binding to liver microsomes occurred. This fraction also bound an appreciable amount of the radioactivity of [125I]parathyroid hormone. The uptake of [125I]calcitonin by liver could be inhibited by the simultaneous injection of unlabelled calcitonin, but not by that of parathyroid hormone, insulin or adrenocorticotrophic hormone.

These results indicate a role for the liver and kidney in the early clearance of calcitonin and parathyroid hormone respectively. It is likely that the liver is the major site of the metabolism of calcitonin in vivo.

Metabolism of parathyroid hormone. Degradation of 125I-labelled hormone by a kidney enzyme

A study was made of the enzymic degradation of (125)I-labelled parathyroid hormone by rat kidney microsomes. Incubation with microsomes resulted in rapid destruction of the labelled hormone. The microsomal factor was not separable by dialysis, and the reaction was favoured by pH values in the physiological range. Velocity of the reaction varied directly as the substrate concentration, and additional crude parathyroid hormone (trichloroacetic acid-precipitated, 3.68mg./ml.) inhibited destruction of labelled hormone. There was much less inhibition with added trichloroacetic acid-precipitated calcitonin (3.92mg./ml.) and virtually none with added pig insulin (3.80mg./ml.). Gel filtration of control medium on P6 (Bio-Gel) yielded one radioactive peak at the void volume. After incubation with microsomes three further peaks were obtained on gel filtration. Only the void-volume peak contained intact (125)I-labelled parathyroid hormone, indicating that the microsomal enzyme degraded labelled hormone to a number of smaller fragments.