Treatment of Hypercalcemia

Efficacy and safety of pamidronate in children with vitamin D intoxication

BACKGROUND

Bisphosphonates are used in the treatment of vitamin D intoxication (VDI) after failure of conventional therapy including prednisolone. Safety concerns restrict the use of bisphosphonates from being used as first-line therapy for VDI in children. The aim of this study was to evaluate the efficacy and safety of pamidronate in comparison with prednisolone in children with VDI.

METHODS

We reviewed the hospital records of children consecutively diagnosed with VDI at two medical centers in a 15 year period.

RESULTS

The subjects consisted of 21 children (age, 0.3-4.2 years) who were treated with prednisolone and/or bisphosphonates. Pamidronate (n = 18) or alendronate (n = 3) was used in six patients after unsuccessful prednisolone treatment, and in 15 patients from baseline. Initial serum calcium and 25-hydroxyvitamin D were 16.1 ± 1.9 mg/dL and 493 ± 219 ng/mL, respectively. The median time to reach normocalcemia in the pamidronate, alendronate and prednisolone groups was 3 days (range, 2-12 days), 4 days (range, 3-6 days) and 17 days (range, 12-26 days), respectively (P = 0.013). The pamidronate group had a fivefold shorter hospital stay than the prednisolone group. Three patients initially treated with prednisolone developed nephrocalcinosis but this did not occur in any patient treated with bisphosphonates from baseline. Apart from transient fever and moderate hypophosphatemia, no side-effect of bisphosphonate treatment was observed.

CONCLUSIONS

Pamidronate is efficient and safe for the treatment of VDI in children. Pamidronate use significantly shortens the duration of treatment, and thereby may prevent the development of nephrocalcinosis. Instead of prednisolone, pamidronate should be used together with hydration and furosemide as the first-line therapy for VDI.

Postanalytical quality improvement: a College of American Pathologists Q-Probes study of elevated calcium results in 525 institutions

OBJECTIVE

To evaluate elevated patient calcium results as a postanalytic quality indicator of physician practices.

DESIGN

Participants prospectively identified hypercalcemic patient results for 4 months or until they found 320 hypercalcemic results, and then, after at least 3 days, reviewed the medical records of these patients. Hypercalcemia was defined as a calcium value that exceeded the upper limit of each laboratory's reference range by 0.12 mmol/L or more. Participants, as well a subset of their physicians who did not acknowledge or respond to elevated results in the medical record, answered a questionnaire about their practices.

PARTICIPANTS

Five hundred twenty-five laboratories enrolled in the College of American Pathologists Q-Probes program.

MAIN OUTCOME MEASURES

The presence of hyercalcemic results in patients' medical records and physicians' acknowledgement and response to those elevated results.

RESULTS

More than 5500 hypercalcemic results were identified, of which 53.2% represented a new finding. About 3.5% of results were not charted in the patients' records, and 23.1% of patient records did not contain clinician documentation of the abnormal result. Follow-up laboratory tests were not ordered for 13.8% of the elevated values. For 570 of the 808 results for which there was neither clinician documentation nor designated follow-up laboratory tests ordered, patients' physicians received written notification of the elevated calcium results along with a questionnaire. Responses were received from 386 physicians (68%). One hundred physicians indicated they did not order the specific calcium measurement, and of these 100, 85 responded it was part of a panel. The 286 physicians who ordered the test stated the results ultimately led to further testing (69%), a change of management (56%), or a new diagnosis (25%).

CONCLUSIONS

We found that a high percentage of abnormal results (3.5%) were not documented in the patients' medical records, the diagnosis of hypercalcemia frequently was new (53.2%), and a high percentage of physicians did not respond to elevated calcium results by writing a note (23.1%) or ordering another test (13.8%). Opportunities for quality improvement at these postanalytical steps are far greater than at the analytical step. Laboratorians must help physicians identify and respond to clinically important laboratory results.

Hypercalcemia and hypermagnesemia

Hypercalcemia and hypermagnesemia occur infrequently in small animal patients. Specific clinical signs usually do not accompany these electrolyte disorders, and their presence is often recognized only after reviewing serum chemistry profile results. The etiologies, clinical signs, and therapies for each electrolyte disorder are discussed in this article. Treatment of these disorders is aimed at correcting the underlying disease process and enhancing the removal of calcium or magnesium from the body. In severe cases, rescue therapies and resuscitative measures are required to stabilize the patient.

Hypercalcaemia in patients with cancer: aetiology and treatment

Hypercalcaemia is one of the most common disorders occurring in patients with cancer and may have disabling symptoms. The mechanisms underlying hypercalcaemia associated with malignant disease, the symptoms attributable to and the treatment of this disorder are discussed in this paper.

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.

Hypercalcemic crisis

Hypercalcemic crisis or severe hypercalcemia represents a life-threatening emergency. The most common cause is hypercalcemia of malignancy, although granulomatous diseases, previously undetected primary hyperparathyroidism, medication-induced hypercalcemia, and a few rarer causes may result in this endocrine emergency as well. The clinical presentation and prognosis depend on the acuity of the development of hypercalcemia, the degree of hypercalcemia, and the underlying cause. Certainly, patients with malignancy who develop hypercalcemia superimposed on their already debilitated state are more likely to have a poor outcome than a previously relatively healthy patient with thiazide-induced hypercalcemia, for example. The clinical presentation of patients with hypercalcemic crisis varies depending once again on the underlying cause and degree and rapidity of the hypercalcemia. Most patients experience some constitutional symptoms, neurologic symptoms, gastrointestinal symptoms, and renal manifestations of hypercalcemia. Immediate and effective therapy directed toward the pathophysiology of hypercalcemia is essential. General measures must be implemented to reverse the dehydration, to promote urinary calcium excretion, to avoid prolonged immobilization, and to identify the underlying cause of hypercalcemia. Specific measures directed at inhibiting bone resorption, increasing renal sodium and calcium excretion, and occasionally at decreasing intestinal absorption of calcium (or more specifically blocking vitamin D metabolism) should also be implemented. Obviously the more reversible the underlying cause of hypercalcemia, the more aggressive one should be with the therapy. The literature was reviewed to compile comparative data that practitioners may use in choosing among the various pharmacologic therapies available for the treatment of acute hypercalcemia. Despite all the advances in the field, hypercalcemic crisis still carries a significant mortality risk, although with appropriate therapy with the aforementioned general and specific measures, the calcium level can effectively be lowered in most patients.

Risedronate activity in the fetal and neonatal mouse

Otosclerosis, chronic otitis media with and without cholesteatoma, and Paget's disease of bone are just a few of the many diseases of the ear that exhibit abnormalities of bone modeling and remodeling. These diseases result in chronic infection, vestibular dysfunction, and hearing loss. Bisphosphonates are a promising new class of drugs potentially useful in the treatment of these disorders. Currently used in diseases with high rates of bone turnover (Paget's disease of bone, hypercalcemia of malignancy, and osteoporosis), they have been found to be strong inhibitors of bone resorption. A third generation bisphosphonate, 2-(3-pyrindyl)-hydroxyethylidene bisphosphonate (risedronate) is being investigated for toxicity, increased efficacy, and oral administration. In this study the in vitro and in vivo anti-resorptive activity of risedronate was quantified by measuring calcium release in a neonatal mouse calvarial culture system. This model was used to test direct in vitro effects, in vivo exposure in neonatal mice, and the possible effects of in utero and lacteal exposure. Calcium release activated by parathyroid hormone (PTH) was significantly inhibited when risedronate was only present in the pre-incubation media. When risedronate was administered subcutaneously to neonatal mice it resulted in a significant decrease in PTH-activated calcium release in explanted calvaria in vitro. Transplacental and lactational transfer of biologically effective risedronate was not demonstrated in this study; however, a paradoxic increase in PTH-stimulated calcium release in vitro from calvaria theoretically exposed transplacentally and lacteally was noted. This effect was unexplained by the data.

Immobilization osteoporosis in paraplegia

The pathophysiology of osteoporosis as it relates to immobilization or disuse osteoporosis in paraplegics is briefly reviewed. The physiology of bone formation and resorption is discussed, and the influence of piezoelectric forces on bone integrity and the consequences of the loss of this effect in paraplegics is addressed. When bone is stressed, negative charges accumulate on the side from which the stress is applied and positive charges accumulate on the opposite side. Presumably the collagenous component of bone plays the major role in the generation of electrical potentials. Another mechanism important in the generation of electrical potentials is created by liquid planes streaming past solid planes. Diminished forces acting on bone, as in paraplegia, are translated into changes in the activity of bone remodeling units which can be assessed by histomorphic and histoenzymatic techniques. Other biochemical and endocrine consequences of immobilization involve increased serum calcium, decreased serum parathyroid hormone (PTH), and decreased dihydroxy-vitamin D synthesis. Urinary hydroxyproline and calcium excretion are increased, as is stool calcium. The bone loss that follows immobilization may produce an increased susceptibility to fractures involving long bones more than the spinal column, and is due more to decreased bone formation than to accelerated bone resorption. The treatment of immobilization osteoporosis primarily involves early remobilization, but other treatments, including the use of electrical fields and the administration of bisphosphonates, calcitonin, and a growth hormone are being actively investigated.

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.

Diagnosis and treatment of patients with parathyroid carcinoma: an update and review

Parathyroid carcinoma is a rare cause of primary hyperparathyroidism. However, to our best knowledge, at least 163 cases of functioning parathyroid carcinoma appeared in the English literature from 1981 to 1989. We summarize the available information obtained from the reports of those patients and compare it with previous descriptions of the disease. The etiology of parathyroid carcinoma is usually obscure, but the possibility of a radiation-induced malignant change in the parathyroid gland became evident in a few patients. Clinical manifestations, including age, sex, symptoms, and biochemical findings in this review were comparable to those in previous reviews. Noninvasive localization studies such as ultrasonography may offer a diagnostic clue to parathyroid carcinoma. Measurement of DNA content is a useful adjunct for making the histologic diagnosis of parathyroid carcinoma and prediction of the clinical outcome. Since the initial operation offers the best chance for cure, pre-operative suspicion and intra-operative recognition of the parathyroid cancer are essential. The initial operation should be en bloc resection of the tumor, avoiding rupture of the tumor capsule and spillage of tumor cells. As parathyroid carcinoma is a slow-growing but tenacious malignancy, repeated resection of local recurrent tumors or even distant metastases is effective for palliation of recurrent hypercalcemia and occasional cure. When hypercalcemia is refractory to surgical therapy or no recurrent tumor can be identified, other modalities of therapy must be considered. New drugs to control hypercalcemia by inhibiting bone resorption may hold promise in patients with recurrent parathyroid carcinoma.