High Serum Alkaline Phosphatase Activity Research Articles

Canine Serum Thermostable Alkaline Phosphatase Isoenzyme From a Dog With Hepatocellular Carcinoma

A dog histopathologically diagnosed with hepatocellular carcinoma (HCC) showed very high serum alkaline phosphatase (ALP) activity. A supernatant of ascitic fluid and tumor tissue extracted from the dog also showed much higher ALP activity than normal. ALP isoenzyme analysis of samples was performed using polyacrylamide gel disk electrophoresis, and a wide, broad abnormal band was observed. By various treatments, the abnormal band showed thermostability, which is a characteristic of tumor-associated ALP that has only been reported in humans. The thermostable ALP isoenzyme was not found in sera from 39 dogs with several types of tumor that originated from the liver, except for HCC, nor was it found in 10 dogs with hepatic diseases that did not include hepatic tumors. The thermostable ALP isoenzyme seemed to be associated with canine HCC.

The calcium and phosphorus content of giraffe (Giraffa camelopardalis) and buffalo (Syncerus caffer) skeletons

AbstractOsteophagia, variable serum calcium (Ca) and phosphorus (P) concentration, high serum alkaline phosphatase activity, a high growth rate, and a large skeletal mass, all suggest that Ca and P requirements and availability are finely balanced in giraffes. The mineral content of some marker bones in skeletons obtained from adult male giraffes (browsers) and adult male African buffaloes (grazers of similar body mass) were compared to assess the idea of critical Ca and P balance. Our results show that the P concentration of plasma varies more than Ca concentration, and that the Ca content of giraffe bones (0.196±0.01 g/g) and buffalo (0.202±0.006 g/g) varies more than P content (0.095±0.002 in both). The average Ca and P content of the bones analysed was similar in both species (Ca=∼20.0%, P=∼9.5%). Giraffe skeletons, however, contain three times more Ca and P than do buffalo skeletons. This translates into a 1.5–2.0 fold higher Ca requirement for giraffes, with which they seem to cope effectively by selection for Ca‐rich, dicotyledonous, browse. Sources of P to meet requirements are not obvious and a seasonal deficiency of P is a more likely cause of observed osteophagia than Ca deficiency. Giraffe rib P density, the best measure of P balance, of 0.142±0.01 g/cm3 is, however, above the deficiency threshold. Bone mineral content (Ca and P) correlates well with bone density and shows only slight differences between adult males of the two species.

Osteoprotegerin regulates bone formation through a coupling mechanism with bone resorption.

Deficiency of osteoprotegerin (OPG), a soluble decoy receptor for receptor activator of nuclear factor-kappaB ligand (RANKL), in mice induces osteoporosis caused by enhanced bone resorption, but also accelerates bone formation. We examined whether bone formation is coupled with bone resorption in OPG-deficient (OPG-/-) mice using risedronate, an inhibitor of bone resorption. Histomorphometric analysis showed that bone formation-related parameters (e.g. mineral apposition rate and osteoblast surface/bone surface) in OPG-/- mice sharply decreased with suppression of bone resorption by daily injection of risedronate for 30 d. OPG-/- mice exhibited high serum alkaline phosphatase activity and osteocalcin concentration, both of which were decreased to the levels in wild-type mice by the risedronate injection. Serum levels of RANKL were markedly elevated in OPG-/- mice, but were unaffected by risedronate. The ectopic bone formation induced by bone morphogenetic protein-2 implantation into OPG-/- mice was not accelerated even with a high turnover rate of bone, but attenuation of mineral density from the ectopic bone was more pronounced than that in wild-type mice. These results suggest that bone formation is coupled with bone resorption at local sites in OPG-/- mice, and that serum RANKL levels do not reflect this coupling.

Autosomal dominant hyperostosis/osteosclerosis with high serum alkaline phosphatase activity.

We studied eight affected and four unaffected individuals from a Colombian family with autosomal dominant diffuse high bone density. Affected individuals have normal, proportional height and high serum alkaline phosphatase activity. Radiographically, affected members exhibit generalized, symmetrically diffuse endosteal hyperostosis of the long bones and skull with narrow medullary cavities and loss of the diploë, respectively. There is no periosteal reaction or decreased hematopoiesis. Furthermore, osteosclerosis affects vertebral bodies, ribs, pelvis, mandible, clavicles, and scapulae. Bone mineral density is 2.4-7.3 SD above the mean for age and gender in affected individuals. Affected vs. unaffected individuals' Z-scores were (mean +/- SD) 5.03 +/- 1.77 vs. 0.08 +/- 0.97, respectively, P = 0.0004). Three affected subjects older than 40 yr old lost bone mass in 6 yr. No dysmorphism, abnormal facial features, bone fractures, or cranial nerve involvement was found. The pattern of inheritance, the absence of asymmetries and malformations, the increased serum alkaline phosphatase, the peak bone mass that appears to decrease physiologically with age, and the involvement of cortical and trabecular bone suggest a new variant of hyperostosis/osteosclerosis that affects the entire skeleton.

Idiopathic noncirrhotic portal hypertension in dogs: 33 cases (1982-1998).

To describe clinical signs, diagnostic findings, and outcome in dogs with idiopathic intrahepatic portal hypertension. Retrospective study. 33 dogs. Medical records of dogs with portal hypertension of intra-abdominal origin were reviewed. Dogs with intra-abdominal portal hypertension of vascular causes or with hepatic histopathologic changes consistent with severe diffuse hepatobiliary disease were excluded. History and results of physical examination, clinicopathologic tests, diagnostic imaging studies, histologic examination, and treatment were summarized. Outcome was determined in 26 dogs. Dogs were referred most often because of ascites, intermittent vomiting or diarrhea, and polydipsia of several months' duration. Microcytosis, high serum alkaline phosphatase and alanine transaminase activities, hepatic dysfunction, urine specific gravity < or = 1.021, and abdominal transudate were the predominant clinicopathologic features. Microhepatia, abdominal effusion, and multiple anomalous venous anastomoses were the major findings of diagnostic imaging. Hepatic histopathologic changes were consistent with idiopathic noncirrhotic portal hypertension and were indistinguishable from those of dogs with surgically created portocaval anastomosis. Outcome was determined for 19 dogs released from hospital; 13 dogs remained healthy with mostly palliative treatment for periods of 5 months to 9 years. The clinical signs, clinicopathologic test results, portal pressure, and gross appearance of the liver of dogs with idiopathic noncirrhotic portal hypertension may be identical to those of dogs with cirrhosis; therefore liver biopsy is crucial. Because the prognosis for idiopathic noncirrhotic portal hypertension is generally favorable, owners of affected dogs should be discouraged from choosing euthanasia.

The effects of vitamin D insufficiency in patients with primary hyperparathyroidism

PURPOSE: Differences in the prevalence of vitamin D deficiency may explain why the frequency of symptoms in patients with primary hyperparathyroidism varies geographically. This study was performed to determine the prevalence in the United States of low 25-hydroxyvitamin D levels among patients with mild primary hyperparathyroidism, and the effect of 25-hydroxyvitamin D status on disease severity. METHODS: We studied 124 patients with mild primary hyperparathyroidism. Biochemical, bone mineral density, and bone histomorphometric indices were compared among patients whose serum 25-hydroxyvitamin D levels were in the lowest and highest tertiles. RESULTS: Serum 25-hydroxyvitamin D levels (mean ± SD) were in the low range of normal (21 ± 11 ng/mL, normal 9 to 52 ng/mL). Levels were below normal in 9 (7%) patients, and below the level suggested for vitamin D “sufficiency” (20 ng/mL) in 66 (53%) patients. Those with lowest 25-hydroxyvitamin D levels had the highest parathyroid hormone levels (low tertile 158 ± 66 pg/mL versus high tertile 103 ± 62 pg/mL, P <0.0001). Other evidence of more active hyperparathyroidism in those with low 25-hydroxyvitamin D levels included higher serum alkaline phosphatase activity (114 ± 48 U/L versus 91 ± 35 U/L, P <0.03), lower serum phosphorus levels (2.7 ± 0.4 mg/dL versus 3.0 ± 0.4 mg/dL, P <0.01), and greater bone mineral density at the lumbar spine (0.94 ± 0.03 g/cm 2 versus 0.83 ± 0.03 g/cm 2, P <0.05) reflecting the protective effects of parathyroid hormone on cancellous bone. They also had enhanced bone turnover on bone biopsy. Despite the expected differences in vitamin D metabolism in African-Americans, results did not differ by race. CONCLUSION: Vitamin D insufficiency or deficiency is common among patients with mild primary hyperparathyroidism. In these patients, the effects of primary hyperparathyroidism on biochemical, densitometric, and histomorphometric indices are more pronounced.

Bone-sparing effect of soy protein in ovarian hormone–deficient rats is related to its isoflavone content

Our previous studies showed that a soy-protein diet prevents ovariectomy-induced bone loss. The purpose of this study was to determine whether isoflavones in soy protein are responsible for this bone-protective effect. Forty-eight 95-d-old Sprague-Dawley rats were divided into 4 groups: sham-operated fed a casein-based diet (SHAM), ovariectomized fed a casein-based diet (OVX+CASEIN), ovariectomized fed soy protein with normal isoflavone content (OVX+SOY), and ovariectomized fed soy protein with reduced isoflavone content (OVX+SOY-). The OVX+SOY group had significantly greater femoral bone density (in g/cm3 bone vol) than the OVX+CASEIN group, whereas OVX+SOY- was similar to OVX+CASEIN (mean +/- SD; SHAM, 1.522 +/- 0.041; OVX+CASEIN, 1.449 +/- 0.044; OVX+SOY, 1.497 +/- 0.030; OVX+SOY-, 1.452 +/- 0.030). Ovariectomy resulted in greater bone turnover as indicated by higher serum alkaline phosphatase activity, serum insulin-like growth factor I and insulin-like growth factor binding protein 3 concentrations, and urinary hydroxyproline. These increases were not affected by soy with either normal or reduced isoflavone content. Similarly, histomorphometry revealed a greater bone formation rate with ovariectomy, and this was not altered by the soy diets. The findings of this study suggest that isoflavones in soy protein are responsible for its bone-sparing effects. Further studies to evaluate the mechanism of action of isoflavones on bone are warranted.

Cycad palm toxicosis in dogs: 60 cases (1987-1997)

Objective To report clinical and epidemiologic information, summarize characteristic clinical signs and laboratory results, and describe the expected course of cycad toxicosis in dogs. Design Retrospective study. Animals 60 dogs with evidence of cycad ingestion. Procedure The National Animal Poison Control Center's case record database was searched for records of dogs ingesting cycad plants from January 1987 to November 1997. Data were retrieved on clinical signs, laboratory test results, exposure history, and physical examination findings. Cases were assessed as toxicosis, suspected toxicosis, or possible toxicosis. Results Records from 60 dogs were retrieved; 89.7% of the dogs were from the southern United States, 38.7% ingested seeds, 95% developed liver and gastrointestinal tract problems, and 53.3% had abnormal neurologic signs. High serum bilirubin concentration and alkaline phosphatase and alanine aminotransferase activities were the most common serum biochemical abnormalities. Although clinical signs were observed within 1 day, laboratory values did not change for 24 to 48 hours after cycad ingestion. Mortality rate was reportedly 32.1 %. Clinical Implications 68% of dogs responded well to treatment and supportive care. Dogs ingesting seeds are likely to develop more serious problems. Clinical signs can develop within 1 to 3 days and can last for several days. A tentative diagnosis should be made on the basis of history of ingestion, clinical signs, and duration of signs. Because of the nature of these toxins, cycad ingestion is serious and should be treated aggressively. (J Am Vet Med Assoc 1998;213:99-101)

Rapid skeletal turnover and hypercalcemia associated with markedly elevated interleukin-6 levels in a young black man

A 24-year-old black man presented with diffuse musculoskeletal pain and shotty lymphadenopathy. Laboratory studies revealed hypercalcemia and hyperphosphatemia, very high serum alkaline phosphatase activity, diffuse but intense uptake of radionuclide on a bone scan, urinary N-telopeptide excretion 30 times the upper limit of normal, and serum interleukin-6 100 times the upper limit of normal. An extensive workup for etiologies of the disorder was negative. A bone biopsy revealed intense osteoclastic resorption coupled with rapid bone formation and/or remodeling. This case appears to represent a new entity. Treatment with bisphosphonates produced symptomatic and biochemical improvement.

Hypothyroidism in dogs: 66 cases (1987-1992)

Abstract Sixty-six dogs with hypothyroidism were identified from dogs examined over a 5-year period. Hypothyroidism was diagnosed only if the dog had a low, resting serum thyroxine concentration and serum thyroxine concentration was not higher than the lower limits of the reference range 6 hours after iv administration of bovine thyrotropin. The prevalence of hypothyroidism was 0.2%. Neutering was determined to be the most significant gender-associated risk factor for development of hypothyroidism. Neutered male and spayed female dogs had a higher relative risk of developing hypothyroidism than did sexually intact females. Sexually intact females had a lower relative risk. Breeds with a significantly increased risk, compared with other breeds, were the Doberman Pinscher and Golden Retriever. The most common clinical findings were obesity (41%), seborrhea (39%), alopecia (26%), weakness (21%), lethargy (20%), bradycardia (14%), and pyoderma (11 %). Low voltage R-waves were found, on 58% of ecg. Clinicopathologic abnormalities included hypercholesterolemia (73%), nonregenerative anemia (32%), high serum alkaline phosphatase activity (30%), and high serum creatine kinase activity (18%). Serum total triiodothyronine concentrations were within reference ranges in 15% of the hypothyroid dogs. Response to treatment was good in most dogs, but those with severe concurrent disease or neurologic abnormalities were less likely to respond with complete resolution of clinical signs.

Effect of Milk Whey and Its Fermentation Products by Lactic Acid Bacteria on Mitochondrial Lipid Peroxide and Hepatic Injury in Bile Duct-ligated Rats

The study was carried out to assess whether bovine milk whey and its products fermented by lactic acid bacteria could ameliorate the lipid peroxidation of hepatic mitochondria associated with cholestatic liver injury due to bile duct ligation. Rats were maintained on one of five diets for 3 weeks before being operated upon and killed 3 weeks after bile duct ligation. The diets included one deficient in vitamin E (control diet) and others supplemented with either 5% milk whey or 5% milk whey fermented with Bifidobacterium longum (B. longum), Lactobacillus acidophilus (L. acidophilus), and Streptococcus salivarius subsp. thermophillus (S. thermophillus). Bile duct-ligated rats, compared with sham-operated rats, had higher organ weights (liver and spleen), higher serum alkaline phosphatase activity, higher serum bilirubin concentration, and higher content of hepatic mitochondrial lipid hydroperoxide. The rats fed on diets containing milk whey fermented with B. longum ameliorated the elevation of organ weight...

Granulomatous hepatitis in dogs: Nine cases (1987–1990)

Summary Granulomatous hepatitis (gh) is an uncommon histopathologic diagnosis in dogs. On the basis of clinical reports, fungal infections appear to be the most common cause of gh in dogs, but many other potential causes have been identified. The medical records and histopathologic findings for 9 dogs with gh were reviewed to identify additional specific causes of gh in dogs. Diseases associated with gh included intestinal lymphangiectasia (n = 2), lymphosarcoma (n = 1), histiocytosis (n = 1), dirofilariasis(n = 1), and histoplasmosis (n = 1). In 1 dog, no other disease process was identified. Of the remaining 2 dogs, 1 had concurrent granulomatous pneumonitis of unknown cause, and the other had periportal hepatitis and temporal muscle wasting. All 9 dogs with gh had clinical evidence of liver disease, such as hepatomegaly, icterus, and ascites, or had high serum alkaline phosphatase and alanine aminotransferase activity. Because of the wide variety of potential causes of gh in dogs, an accurate diagnosis should be sought so that appropriate treatment can be chosen and an accurate prognosis given.

Ｘ線像で多発性骨融解像を呈した成人Ｔ細胞白血病の一例

A case with adult T-cell leukemia was reported. A 52-year-old man had suffered from low back, bilateral hip joint, and bilateral thigh pain for three years. Multiple osteolytic lesions were found on roentgenogram. Laboratory examination showed normal serum calcium, low serum phosphorus, high serum alkalinephosphatase activity, and normal parathyroid hormone level. Anti HTLV-1 antibody dwas positive and flower cells were found in peripheral blood. Bone biopsy was performed in right femur. Proliferation of osteoclasts and excessive bone resorption were observed but not ATL cells.

Detection of serum α-fetoprotein in dogs with hepatic tumors

Summary Serum α-fetoprotein (afp) concentration was detected by use of 2 commercially available kits containing antibodies to human afp—a radioimmunoassay and an enzymetric test. Using neonatal canine serum (a source high in afp), it was determined that reagents from both kits were able to bind to canine afp, but a significant difference was detected in afp concentration. The enzymetric test was superior in detecting canine afp. Sera from dogs were classified into 6 groups: from dogs with primary hepatic tumors only (group 1); from dogs with primary hepatic tumors and other tumors (group 2); from dogs with normal liver but with other types of neoplasia (group 3); from dogs with nonneoplastic hepatic disease and tumors originating in other organs (group 4); from dogs with nonneoplastic hepatic disease only (group 5); and from clinically normal dogs (group 6). Serum biochemical determinations (alkaline phosphatase, alanine transaminase, albumin, total protein, total bilirubin, and serum bile acids) and values from the 2 afp assays were obtained for all dogs. Serum afp concentration detected by the enzymetric test was significantly higher in dogs with hepatocellular carcinoma and cholangiocarcinoma. Values &gt; 250 ng/ml were detected in 5 of 9 dogs with cholangiocarcinoma and in 3 of 4 dogs with hepatocellular carcinoma. High serum afp concentration also was indicative of liver involvement in 2 of 3 dogs with primary hepatic lymphosarcoma; 2 dogs had values &gt; 225 ng/ml. Serum afp concentration in dogs with other types of hepatic tumors was &lt; 250 ng/ml, and serum afp concentration could not be correlated with such tumors. Discriminatory analysis was done to determine which serum biochemical values best aided differentiation of hepatic neoplasia from nonneoplastic hepatic disease. Along with high serum afp concentration, high serum alkaline phosphatase activity and low albumin concentration were the most important analytes. If hepatic tumor is suspected, we recommend use of the enzymetric test to determine afp concentration, in addition to use of serum biochemical values, clinical findings, and radiography, to aid in the diagnosis.

Calcium and phosphorus deficiencies affect mineral distribution in neonatal miniature piglets

Current efforts to monitor the mineral status of preterm infants fed human milk may not provide sufficient information on the distribution of body minerals. To investigate the body distribution of calcium and phosphorus during various degrees of mineral deficiency, neonatal miniature piglets were raised for 2 wk on diets differing only in calcium and phosphorus. Groups A, B, and C were fed 100%, 60%, and 20%, respectively, of the recommended amounts of calcium and phosphorus that, when adjusted for rates of growth, approximated the range of dietary intakes of preterm infants. Group C manifested biochemical and body-composition evidence of mineral deficiency when compared with group A: lower serum phosphorus; higher serum alkaline phosphatase activity; less fat-free tissue, calcium, and phosphorus in tibiae, vertebrae, and whole carcasses. Neonatal miniature piglets are useful for studying mineral deposition during mineral deficiency in preterm infants.

REDUCED FOREARM BONE MINERAL CONTENT AND BIOCHEMICAL EVIDENCE OF INCREASED BONE TURNOVER IN WOMEN WITH EUTHYROID GOITRE TREATED WITH THYROID HORMONE

We used single-photon absorptiometry to assess forearm bone mineral content (BMC/BW) (arbitrary units normalized for bone width) at a proximal site (PBMC/BW) and at a more distal site (DBMC/BW) in 60 women treated with 25-50 micrograms T3 or 50-100 micrograms T4 for euthyroid goitre, in 13 untreated goitre patients, and in 2 controls matched for age and menopausal state for each goitre patient. BMC/BW was not significantly different between untreated goitre patients and controls. In 36 premenopausal patients, treated for 5.8 +/- 5.4 years (mean +/- SD) a slight decrease in PBMC/BW of about 5% compared to controls to controls was observed (PBMC/BW 1.42 +/- 0.19 vs 1.49 +/- 0.13, P less than 0.05). In 24 postmenopausal patients, treated for 10.0 +/- 5.8 year, a 20% deficit in BMC/BW compared to controls was found (DBMC/BW 0.80 +/- 0.18 vs 1.06 +/- 0.20, P less than 0.001 and PBMC/BW 1.14 +/- 0.20 vs 1.42 +/- 0.19, P less than 0.001). Biochemical indices of bone metabolism in 43 pre and post-menopausal patients and 43 controls showed in the patients a higher serum alkaline phosphatase activity (AP) (P less than 0.01 and P less than 0.05 and serum osteocalcin (NS and P less than 0.05). AP was negatively correlated with TSH levels and, in postmenopausal patients, with DBMC/BW and PBMC/BW. Our results suggest that treatment of euthyroid women with moderate doses of thyroid hormone increases bone turnover with clear adverse effects on bone mineral status in postmenopausal patients.

The role of maternal alcohol damage on ethanol teratogenicity in the rat.

To study the severity and degree of in utero alcohol effects in relation to the rate of maternal alcohol damage, multiparous 1-year alcohol-fed rats were used, with an appropriate pair-fed control group. During pregnancy, alcoholic dams showed relatively high acetaldehyde levels (41 +/- 19 mumol/l) and blood alcohol levels of 22.8 +/- 14 mmol/l. They also showed marked histological alterations in liver as well as high serum aspartate-aminotransferase, alanine-aminotransferase, alkaline phosphatase, glutamate dehydrogenase, and gamma-glutamyltransferase activities. The increase in serum enzyme levels did not correlate with an increase in hepatic enzyme levels since only glutamate dehydrogenase was enhanced in liver after 1 year of alcohol intake. In addition, except for an increase in low Km aldehyde dehydrogenase activity, there were no changes in liver alcohol metabolizing enzymes in chronic alcohol vs. pair-fed females. Alcoholic rats showed a high incidence of damage in their progeny (resorptions, immature fetuses, decrease in fetal weight, etc.), and rats with the highest serum levels of the above enzymes (especially glutamate dehydrogenase and gamma-glutamyl transferase) had severely affected progeny. Rats with minimal histological liver damage, in contrast, did not show resorptions. Thus, the results presented suggest that the stage of maternal alcohol illness, as indicated mainly by the extent of liver damage, plays an important role in the frequency and severity of in utero alcohol effects in the rat.

The pathogenesis of infantile malignant osteopetrosis: Bone mineral metabolism and complications in five infants

Bone mineral metabolism was studied in five infants aged 8 to 22 months with severe osteopetrosis. There were findings consistent with biochemical osteomalacia. These included hypocalcemia, hypophosphatemia, high serum acid phosphatase and alkaline phosphatase activity, high levels of serum parathyroid hormone, and high urinary cyclic AMP. Serum 1,25(OH) 2 vitamin D 3 level was high in the one patient tested. Radiographs in all infants revealed rachitic changes in the metaphyses. However, dense bones on radiographs, calcium balance studies, and radiocalcium absorption studies demonstrated markedly positive calcium balance. Iliac crest bone biopsies showed increased quantity of woven bone with abundant numbers of osteoclasts, excessive amounts of osteoid, myelofibrosis, and a decreased number of Howship's lacunae. The wide bands of unmineralized osteoid did not take up tetracycline. In vitro bone resorbing activity due to osteoclast activating factor from cultured stimulated leukocytes was normal. Bone turnover however, was low as evidenced by low urinary hydroxyproline levels. We interpret these findings as indicating there is decreased bone remodeling and resorption in spite of increased humoral stimuli and osteoclasts. Since calcitonin levels were normal for age, the most likely cause of the impaired bone remodeling sequence was defective osteoclast function. We postulate that there may be a common genetic defect in phagocyte cells, including monocytes, neutrophils, and osteoclasts, which accounts for the abnormalities of mineral metabolism and previously reported hematologic, neurologic, and infectious complications.

Postoperative management of primary hyperparathyroidism.

Postoperative management of patients with primary hyperparathyroidism requires to determine whether the operation has succeeded or not in early postopera­ tive days as well as to deal with postoperative hypoparathyroidism. Twenty three surgically managed patients with primary hyperparathyroidism were studied. Attention was focused on the time course of postoperative serum calcium levels and postoperative hypocalcemic signs. The following conclusion were obtained. When the surgery was successful, the serum total calcium levels fell·to normal range within 48 hours, then below normal range and gradually returned to normal. It took about one to three months for the serum calcium levels to return to normal. Severe postoperative hypocalcemic signs were observed in those patients with extensive bone disease and high serum alkaline phosphatase activities, in those where initial hypocalcemic signs appeared within 24 hours after surgery, and in those where plasma total calcium levels continued to decrease after the fourth postoperative day. Calcium should be administered only to patients with severe hypocalcemic signs or to those with postoperative congestive heart failure. The second exploration should be performed without delay when the fluctuating hypercalcemia persists after the operation.