Therapy of hypercalcemia of malignancy

Calcium free hemodialysis: experience in the treatment of 33 patients with severe hypercalcemia

OBJECTIVE

To assess the efficacy, adverse effects and relevance of calcium-free hemodialysis (CFHD) in the treatment of major hypercalcemia.

DESIGN

Retrospective chart review.

SETTING

Medical ICU.

PATIENTS

All patients admitted over a 9-year period for hypercalcemia requiring urgent treatment and who underwent hemodialysis.

INTERVENTIONS

CFHD with an acetate dialysate.

MAIN RESULTS

Thirty-three patients with severe hypercalcemia from various etiologies received CFHD. Marked and rapid decrease of serum total calcium was obtained during all sessions (mean decrease: 1.71 +/- 0.54 mmol/l). Calcium rebound within 24 h after CFHD was observed in all evaluable cases (1 +/- 0.45 mmol/l; mean delay 13.7 +/- 5.8 h). Adverse cardiovascular effects occurred in 17 of 48 sessions (35%) and in 13 of 30 evaluable patients (43%).

CONCLUSIONS

Adverse effects are frequent during CFHD. After correction of hypovolemia, its use should be restricted to patients with severe clinical symptoms or advanced renal impairment.

Evaluation of a 24-hour infusion of etidronate disodium for the treatment of hypercalcemia of malignancy

BACKGROUND

Hypercalcemia is a serious and common complication of malignancy. Etidronate, a known inhibitor of osteoclastic bone resorption, is approved in the therapy of hypercalcemia of malignancy (HCM) at a dose of 7.5 mg/kg/day infused during a period of 2-4 hours on 3 consecutive days. A multicenter study was conducted to evaluate the safety and efficacy of a single 24-hour infusion of etidronate disodium in patients with HCM.

METHODS

Selected patients with HCM had disease refractory to at least 24-hours of intravenous fluid (more than 3 l/day) with two albumin-adjusted serum calcium concentrations greater than 11.5 mg/dl drawn 24 hours apart before etidronate treatment. Thirty patients were enrolled; 13 received 25 mg/kg for 24 hours, 12 received 30 mg/kg for 24-hours, 3 received incorrect doses (2 overdoses, and 1 underdose) and 2 died of disease-related complications before day 7. Of the 25 evaluable patients, 15 were men and 10 were women. Median age was 53 years (range, 20-75 years). Twelve patients (6 in each treatment group) had confirmed skeletal metastases.

RESULTS

During the week after treatment, the 25 mg/kg group had adjusted serum calcium levels fall from a mean preinfusion baseline of 13.3 +/- 0.3 mg/dl (plus or minus the standard error of the mean) to a mean nadir of 10.9 +/- 0.4 mg/dl (the average of each patient's lowest calcium values). The 30 mg/kg group had adjusted serum calcium levels fall from a mean preinfusion baseline of 13.8 +/- 0.4 mg/dl to a mean nadir of 10.5 +/- 0.3 mg/dl. The average day that nadir occurred was day 5.7 for the 25 mg/kg group and day 5.6 for the 30 mg/kg group. The mean maximum reduction (delta) derived from the patients' nadirs in the 25 mg/kg dose group was 2.5 +/- 0.4 mg/dl and 3.3 +/- 0.3 mg/dl for the 30 mg/kg dose. Time to effect (either a partial response defined as a 15% or greater decrease in the adjusted serum calcium from the preinfusion value or a complete eucalcemic response defined as a reduction to the laboratory's eucalcemic range) occurred on average on day 4.6 in the 25 mg/kg group and day 3.7 in the 30 mg/kg group. Nine of the 13 (69%) patients in the 25 mg/kg treatment group had either partial or complete response to the 24-hour infusion. Five of these patients (38% of the 13 patients) of the 25 mg/kg group had serum calcium levels fall to their laboratory's eucalcemic range before day 7 (a complete response), 4 (31%) had partial response only, and 4 had no response. In the 30 mg/kg group, 11 of 12 (92%) patients had at least partial responses. Eight of the 12 (67%) patients had adjusted serum calcium concentrations fall to the eucalcemic range by day 7, 3 (25%) had a partial response, and 1 had no response. Reported adverse experiences generally were attributable to the underlying disease. The reduction in the serum calcium throughout the week for the 30 mg/kg dose group was significantly greater than that for the 25 mg/kg group (analysis of variance, P < 0.0001).

CONCLUSIONS

Etidronate, when administered intravenously at 30 mg/kg during a period of 24 hours, apparently was safe and effective in this study for treatment of hypercalcemia in patients with a wide variety of tumor types. This regimen may offer a more convenient method of administration than does standard etidronate therapy for the treatment of HCM.

Intravenous disodium etidronate therapy in spinal cord injury patients with heterotopic ossification

The goal of the present study was to use intravenous etidronate in the acute phase of heterotopic ossification (HO) in an attempt to achieve a high initial drug concentration at the site of the active ectopic ossification. The study included 27 consecutive patients with an acute onset of HO after spinal cord injury (SCI). The three-phase bone scan was used to confirm clinical diagnosis of HO. Disodium etidronate (Didronel) 300 mg was administered intravenously daily for 3 to 5 days. In 20 patients there was a rapid (1-2 days) decrease of soft tissue swelling (p < 0.01) with no side effects associated with the intravenous administration. In seven patients there was minimal or no improvement of edema after intravenous etidronate. In these patients deep vein thrombosis was found in the affected limbs. The effect of high dose etidronate on HO was determined in the group of 13 patients with positive clinical and scintigraphic finding of an acute HO, but negative radiographic studies. After intravenous administration of etidronate for 3 days (300 mg/day) the drug was continued orally with 20 mg/kg/day for 6 months. A placebo was not used in this study. In eight patients there was no radiographic evidence of HO after therapy while two patients had minimal ossifications. In three patients therapy was interrupted and all developed HO in 1-2 months.

Mithramycin: a very strong metal chelating agent

The interaction of mithramycin (MTR) with Ca2+, Cd2+, Tb3+, Gd3+, Li+, Na+ and K+ ions has been studied by circular dichroism and absorption spectroscopy. Mithramycin binds strongly to Ca2+, Cd2+, Tb3+ and Gd3+ forming a 1:4 Ca2+: MTR entities with a left-handed screw conformation. The concentration of Ca2+ present in water currently used being about 10 microM, this leads to the conclusion that, in most of the experiments reported in the literature, about 40 microM mithramycin were actually bound to Ca2+. Mithramycin also binds to Na+, forming entities with left-handed screw conformation, but not to K+ and Li+. None of these cations were able to promote the mithramycin-DNA interaction.

Filtering clinically significant hypercalcaemia from non-significant hypercalcaemia at the laboratory level

In an earlier study it was shown, that, in a hospital population, only about 30% of patients with hypercalcaemia had the diagnosis identified and so an alarm filter was developed, at the laboratory level, to differentiate between clinically significant and clinically non-significant hypercalcaemia. The filter correctly classified 84% and 77% of women and men with hypercalcaemia, respectively, with respect to the clinical significance of the hypercalcaemia. The sensitivity and the specificity of the discriminant functions were 90% and 73% in women and 80% and 67% in men. The alarm filter was based on a two-step procedure. The patients were primarily classified by the discriminant functions into one of the following medical diagnoses related to hypercalcaemia: primary hyperparathyroidism, malignancy, and transient hypercalcaemia. Based on this classification the patients were characterized as having either a clinically significant or non-significant hypercalcaemia. The alarm filter was based on two discriminant functions. The discriminant variables were phosphate, albumin, protein, LD, and a haemoglobin in women, and albumin, protein, ALP, and age in men. Missing values were estimated. The discriminant variables were selected from 17 possible discriminant variables, all measured by routine, and age. The study group comprised 257 patients with hypercalcaemia, consecutively registered, during half a year. The classification efficiency of the discriminant functions were based on comparison of results obtained by cross-validation of the discriminant functions, and the medical diagnosis decided by the clinicians in the respective departments of the hospital. The medical diagnoses were based on principles and definitions generally used in the departments with no knowledge of the results assessed by the discriminant functions.

Nasal human calcitonin for tumor-induced hypercalcemia

We treated four hypercalcemic cancer patients by nasal hCT, 3 x 2 mg daily, which has been reported to be active in Paget's disease at lower doses. Only one patient became normocalcemic and mean (+/- SEM) calcium levels fell from 11.6 +/- 0.2 mg/dl before therapy to 10.7 +/- 0.6 mg/dl 2-3 days after starting hCT. The tolerance was excellent but, because of insufficient efficacy, we do not recommend this form of therapy for cancer hypercalcemia.

Effects of mithramycin on calcium metabolism and bone in dogs

Mithramycin (0.1 mg/kg) was administered intravenously to eight Beagle dogs on days 0 and 7 to determine its effects on calcium and phosphorus metabolism, serum parathyroid hormone concentration, osteoclastic bone resorption, and serum biochemical and hematologic parameters. Ionized calcium concentration was paradoxically increased on day 1 and decreased on day 8 in association with an increased serum parathyroid hormone concentration. Serum phosphorus concentration was decreased on days 1 and 2. Osteoclastic bone resorption in iliac cancellous bone was significantly decreased on day 8. There were mild increases in serum alkaline phosphatase (days 1, 2, 4, 8, 9), aspartate aminotransferase (day 9), and gammaglutamyl transpeptidase (days 7, 9) activities. Platelet numbers were increased on days 7 through 13, and packed red blood cell volumes were mildly decreased. This investigation demonstrates that two doses of mithramycin can be administered safely to dogs and may inhibit bone resorption in diseases associated with increased osteoclastic bone resorption, such as humoral hypercalcemia of malignancy.

Direct and indirect assessment of the parathyroid hormone response to pamidronate therapy in Paget's disease of bone and hypercalcaemia of malignancy

In patients with either Paget's disease or hypercalcaemia associated with malignancy (HCM) we have assessed the parathyroid response to pamidronate therapy, both by immunoassay of serum intact parathyroid hormone PTH (1-84) and by measurement of indirect parameters of PTH bioactivity, tubular maximum reabsorption of phosphate (TmPO4/GFR) and nephrogenous cyclic AMP (NcAMP). In 12 patients with Paget's disease, therapy with pamidronate produced a small but significant decrease in adjusted serum calcium within the reference interval which was accompanied by a progressive increase in PTH (1-84) secretion and a corresponding fall in TmPO4/GFR and increase in NcAMP. In 12 patients with HCM pretreatment, PTH (1-84) concentrations were suppressed, whilst mean TmPO4/GFR was reduced and NcAMP was increased, compatible in most patients, with parathyroid hormone-related peptide (PTHrP) driven hypercalcaemia. Therapy with pamidronate produced the expected fall in serum calcium but caused an increase in PTH (1-84) secretion in the presence of absolute hypercalcaemia. The initial subnormal TmPO4/GFR decreased further to a nadir on day 5, and there was a corresponding further increase in NcAMP. By day 7, however, when PTH (1-84) concentrations were maximal, there was a significant paradoxical rise in TmPO4/GFR and a corresponding decrease in NcAMP. These data are consistent with a variable trigger point for PTH (1-84) secretion, one consequence of which is a reduction in the risk of hypocalcaemia following pamidronate. The results have major clinical implications for the interpretation of PTH (1-84) measurements in patients who are being treated or about to be treated for bone disease or for hypercalcaemia of malignancy (HCM).(ABSTRACT TRUNCATED AT 250 WORDS)