Hypercalcemia due to sun exposure in a patient with multiple myeloma and elevated parathyroid hormone-related protein

A patient with multiple myeloma who developed hypercalcemia during three different stages of his disease, with a different hypercalcemic agent elevated in his serum on each occasion, is described. The initial episode of hypercalcemia was associated with high serum interleukin-6 (IL-6). After treatment for myeloma normocalcemia was achieved. Subsequently, a relapse of hypercalcemia occurred, this time characterized by frankly elevated plasma parathyroid hormone-related protein (PTHrP) but normal IL-6. Monotherapy with pamidronate infusions resulted in remission of the hypercalcemia and a significant fall in PTHrP levels. A third spell of hypercalcemia characterized by an acute rise in serum 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D to abnormally high levels occurred during the summer season after prolonged and intense exposure to the sun.     

Ultrastructure of myeloma cells producing parathyroid hormone-related peptide

We examined the ultrastructure of myeloma cells producing parathyroid hormone-related peptide. The nucleus was mature and the cytoplasm was well-developed, being classified into the mature type with slight nucleo-cytoplasmic asynchrony. Although various nuclear and cytoplasmic abnormalities commonly observed in myeloma cells were recognized, a multilamellar body-like structure which has not been reported previously in myeloma cells was characteristically observed. Numerous nuclear and cytoplasmic abnormalities observed in the myeloma cells of this case were considered to have resulted from increased and aberrant proliferation of myeloma cells. We reported previously that the immature nucleus and various nuclear and cytoplasmic abnormalities are related to poor prognosis. Thus, the ultrastructural findings of myeloma cells in this case is not inconsistent with the short survival time.     

Hypercalcemia and parathyroid hormone-related protein in hepatocellular carcinoma

ABSTRACT— A two-site immunoradiometric assay (IRMA) of parathyroid hormone-related protein (PTHrP) was employed to react with circulating concentrations of PTHrP in 14 patients with hepatocellular carcinoma (HCC) and hypercalcemia (> 10.6 mg/dl). Eleven of them had unresectable lesions and three received transcatheter arterial chemo-embolization (TACE) treatment. Patients had no evidence of bony metastases and only one had evidence of a parathyroid lesion (by bone scan and serum parathyroid hormone level, respectively). The urinary cAMP level was increased in all patients, but the serum 1,25-dihydroxyvitamin D and plasma cAMP levels varied. Twelve patients had elevated alpha-fetoprotein (AFP) (> 400 ng/ml) and two of them had mildly elevated AFP levels (11 and 147 ng/ml). Their PTHrP concentrations were elevated (7.1 to 33.2 pmol/l), compared with normal levels obtained in our laboratory (< 3.5 pmol/l). A significant decrease in plasma PTHrP (from 27.4 to 5.2 pmol/1), serum calcium concentrations (from 16.3 to 9.4 mg/dl) and AFP levels (from 64 787 to 3129 ng/ml) was observed on the day following TACE treatment. These results, by using an improved technique, extend the findings that hypercalcemia in patients with HCC is associated with increased renal reabsorption of calcium and increased bone resorption of PTHrP generated by HCC.     

Elevation of circulating plasma cytokines in cancer patients with high plasma parathyroid hormone-related protein levels

Parathyroid hormone (PTH) and PTH-related protein/peptide (PTHrP) bind to the same PTH/PTHrP receptor and stimulate osteoblasts to secrete pro-inflammatory cytokines like interleukin (IL)-6. In patients with primary hyperparathyroidism, elevation of plasma levels of tumor necrosis factor (TNF)-alpha and IL-6 was also described. We, therefore, postulated that PTHrP secreted from cancer cells stimulates the secretion of cytokines and causes increases in their blood levels. Blood concentrations of several cytokines (TNF-alpha, IL-1beta, IL-5, IL-6, IL-8, IL-11 and IL-12) in cancer-bearing patients with or without elevation of blood PTHrP were measured by ELISA. The patients with high plasma PTHrP levels (n=29, intact PTHrP: 8.5 +/- 1.4 pmol/l, normal: <1.1) had higher serum type 1 collagen C-telopeptide (ICTP). Twenty of the patients were hypercalcemic. Plasma concentrations of TNF-alpha, IL-6 and IL-8 were significantly increased in patients with high PTHrP, in either the presence or absence of hypercalcemia. The concentrations of TNF-alpha and IL-6 were also significantly correlated with those of PTHrP. Our observations indicate that high plasma levels of PTHrP in cancer-bearing patients contribute not only to the development of hypercalcemia, but also to the development of the syndrome caused by an excess of pro-inflammatory cytokines.     

Measurement of parathyroid hormone-related peptide in the circulation.

Newly developed assays for the measurement of circulating levels of parathyroid hormone-related peptide may become useful in distinguishing the syndrome of humoral hypercalcemia of malignancy from hypercalcemia of other etiologies.     

Lung cancer associated with hypercalcemia induced by concurrently elevated parathyroid hormone and parathyroid hormone-related protein levels

In general, many cases of malignancy-associated hypercalcemia are due to HHM. In patients with humoral hypercalcemia of malignancy (HHM), it has been reported that plasma parathyroid hormone-related protein (PTHrP) and cyclic adenosine monophosphate (cAMP) levels were elevated, while plasma PTH and active vitamin D(3) levels were suppressed. Our patient showed hypercalcemia with a concurrent increase in plasma and tumor tissue PTHrP and PTH concentrations and also high cAMP and low 1-25(OH)(2)VD(3) levels in the plasma. These data suggest that the hypercalcemia exhibited by our patient was consistent with HHM due to lung cancer and its liver metastasis. Moreover, diagnostic imaging and autopsy findings showed no appreciable lesions of the parathyroid gland. In addition, histopathologic examination of the primary and metastatic tumors revealed the existence of PTH immunohistochemically stained with anti-PTH antibodies, suggesting an ectopic-PTH-producing lung tumor. From these data, our patient was diagnosed with a rare case of lung cancer, which produced both ectopic PTH and PTHrP.     

Hypercalcemia mediated by parathyroid hormone-related protein in the blastic phase of chronic myelogenous leukemia

A 45-year-old man with chronic myelogenous leukemia (CML) in the accelerated phase was admitted to our hospital because of lower back pain and hypercalcemia. On admission, he was confused and found to have massive splenomegaly. The hypercalcemia and splenomegaly improved significantly after administration of incadronate, hydroxyurea, vincristine and prednisolone. Splenomegaly recurred after cessation of the chemotherapy, and examination of the peripheral blood showed 31% blasts, positive for both CD13 and CD33, on which basis myeloid blastic transformation was diagnosed. Vindesine, cytarabine and prednisolone were administered, and the splenomegaly improved again. On admission, when the patient's serum calcium level was 16.0 mg/dl, his serum parathyroid hormone-related protein (PTHrP) level was elevated to 118.3 pmol/l. Furthermore, RT-PCR analysis revealed that the patient's CML cells expressed PTHrP mRNA, and a high level of PTHrP was detected in the supernatant of cultured mononuclear cells derived from the patient's peripheral blood. These findings indicated that the hypercalcemia was due to production of PTHrP by the leukemic cells. Several cases of PTHrP. mediated hypercalcemia associated with CML have been reported previously, and are reviewed here.     

Hypercalcemia associated with parathyroid hormone-related protein produced by B-cell type primary malignant lymphoma of the kidney

 A patient with primary non-Hodgkin's (B-cell type) lymphoma of the kidney developed hypercalcemia at the terminal stage of the disease. Although the plasma parathyroid hormone level was low, urinary cyclic AMP excretion was elevated. Serum osteocalcin (BGP) was suppressed and the plasma level of 1,25(OH)₂D was within the normal range. Serum concentrations of PTH-related protein (PTHrP)-like immunoreactivity (PRP-LI) were elevated, and the tissue concentration of PRP-LI in the postmortem lymph node showed high level along with elevated serum PRP-LI, furthermore the production of PTHrP by the tumor was demonstrated by immunohistochemistry and Northern blotting analysis. These findings indicate that the hypercalcemia of the patient was caused by the PTHrP-producing B-cell lymphoma. Hypercalcemia was restored to normocalcemia by bisphosphonate treatment. Our case will add further information on humoral hypercalcemia in B-cell lymphoma, which rarely has been demonstrated to produce PTHrP. Received: 17 July 1997 / Accepted: 2 February 1998     

Production of parathyroid hormone-related protein by cultured human myeloma cells

We examined whether or not parathyroid hormone-related protein (PTH-rP) is produced in cultured human myeloma cells. PTH-rP protein was detected in the cell extract of one (U266) of 6 myeloma cell lines examined by radioimmunoassay. Also we demonstrated the expression of PTH-rP mRNA in all of the 6 lines. These findings indicate that PTH-rP may be one of the factors responsible for the bone destruction or hypercalcemia in multiple myeloma. © 1994 Wiley-Liss, Inc.     

哺乳期甲状旁腺素相关蛋白升高引起高钙血症、重症骨质疏松一例报道

病例报告:患者女,29岁,因"腰痛2个月,双下肢不能站立20余天",于2007年12月入院.患者于2007年9月正常顺产1足月男婴,母乳喂养,乳汁排泌量异常增多,约为2 500～3 000 ml/24 h.2007年10月中旬患者出现腰骶部疼痛,呈持续性、电击样疼痛,自行服用α-D_3(0.25 μg,每天1次)等药物及推拿等治疗,症状改善不明显,11月底出现腰骶部疼痛加重,伴活动受限,双下肢不能站立,自觉口干,多饮、多尿,偶感头晕,无明显头痛,无消瘦,无恶心呕吐,无腹痛便秘,无下肢浮肿,无肌肉萎缩、关节功能障碍等.12月来本院就诊,查腰椎磁共振示:胸12、腰4椎体改变,考虑压缩性骨折.血常规:白细胞5.6×10~9/L,红细胞3.52×10~12/L,血小板221×10~9/L;血生化检验示:血清钙3.4 mmol/L,磷1.22 mmol/L,碱性磷酸酶195U/L,总白蛋白69.2 g/L,白蛋白44.2 g/L,尿素氮8.4 mmol/L,肌酐44 μmol/L,尿酸281 μmol/L,遂以"高钙血症,原发性甲状旁腺功能亢进?"收住内分泌科.     

Hypercalcemia in disseminated coccidioidomycosis: expression of parathyroid hormone-related Peptide is characteristic of granulomatous inflammation

Background.?Hypercalcemia is an uncommon complication of disseminated granulomatous infections. The pathogenesis of hypercalcemia associated with infection is not clear. Methods.?We investigated a case of disseminated coccidioidomycosis with hypercalcemia. We used a sensitive radioimmunoassay to measure serum parathyroid hormone-related peptide (PTHrP) and a mouse monoclonal antibody to PTHrP to immunostain biopsies. Results.?We found elevated serum levels of PTHrP while the patient was hypercalcemic that became undetectable when serum calcium normalized. We also found that the inflammatory cells and some surrounding tissues in skin biopsies expressed PTHrP. PTHrP was expressed by all biopsied lesions of patients with coccidioidomycosis that we examined, whether localized to the lung or disseminated, but no other cases were hypercalcemic. PTHrP was also expressed by the 3 mycobacterial granulomas we examined, and in a lymph node from a patient with sarcoidosis. Conclusions.?The expression of PTHrP is a property of infectious granulomas regardless of etiology or the tissue involved, suggesting that PTHrP expression is part of the normal granulomatous immune response. Hypercalcemia may result if there is disseminated infection and multiple granulomas. We propose that excess production of PTHrP is the cause of hypercalcemia in granulomatous infections.     

Autocrine/paracrine involvement of parathyroid hormone-related peptide in vascular leiomyoma

Vascular leiomyomas are believed to arise from the smooth muscle of blood vessels and are characterized by the proliferation of vascular smooth muscle cells (VSMC) and numerous slit-like vascular lumens. Parathyroid hormone (PTH)-related peptide (PTHrP) plays an important role in local autocrine and/or paracrine regulation of cellular growth and function in VSMC. To investigate the interaction between VSMC and endothelial cells, we evaluated the distribution of PTHrP and PTH/PTHrP-receptor in 10 vascular leiomyomas of the skin by immunohistochemistry and in situ hybridization (ISH) of paraffin-embedded specimens. Both immunohistochemistry and ISH revealed that PTH/PTHrP-receptors are expressed in endothelial cells lining areas with slit-like vascular lumens and very weakly expressed in proliferating VSMC in all vascular leiomyomas. On the other hand, PTHrP itself was localized mainly in proliferating VSMC. These results support the hypothesis that PTHrP acts through the PTH/PTHrP-receptor via an autocrine and/or paracrine mechanism from VSMC to endothelial cells in the formation of characteristic microenvironments of vascular leiomyoma cell composition.     

Sex-specific differences in ventricular expression and function of parathyroid hormone-related peptide

OBJECTIVE: Parathyroid hormone-related peptide (PTHrP) expression is modulated by estrogen. It is expressed in coronary endothelial cells and involved in the endothelium-dependent regulation of coronary resistance and cardiac function. In the present study, we hypothesized that endogenously synthesized and released PTHrP contributes to sex-specific differences in the regulation of cardiac function. METHODS: The influence of sex on ventricular PTHrP expression in normotensive rats was determined via real-time PCR and immunoblot analysis. Sex-specific effects of exogenous PTHrP or endogenous released PTHrP were determined in vitro on isolated ventricular cardiomyocytes, Langendorff preparations on isolated hearts and in vivo using different agonistic or antagonistic PTHrP peptides. RESULTS: Ventricular expression of PTHrP was elevated in hearts from female rats compared to male counterparts. Addition of PTHrP(1-36) did not increase left ventricular function in hearts from either sex, but increased coronary flow in hearts from female rats significantly greater than in those from males. 5Ile-PTHrP(1-36), which was used to antagonize endogenously released PTHrP, reduced left ventricular function in females but not males in vitro and in vivo. Under conditions of increased endogenous PTHrP release, i.e. ischemia-reperfusion, antagonization of PTHrP significantly reduced post-ischemic recovery in hearts from females but not in those from males. CONCLUSIONS: Sex determines the ventricular expression of PTHrP mRNA and protein. The results indicate that PTHrP may improve cardiac function to a greater extent in women than in men following a brief period of ischemia.     

Purification and properties of parathyroid hormone-related peptide isolated from milk

The occurrence and properties of PTH-related peptide (PTH-RP) in milk was investigated. PTH-RP was purified to homogeneity from human and bovine milk using heat and acid to precipitate milk proteins followed by ion exchange chromatography and reverse-phase HPLC. The peak of PTH-RP from HPLC was detected using a sensitive bone cell bioassay. A single band of peptide was detected on silver-stained polyacrylamide gels, which migrated as a 20-21-kDa macromolecule. PTH-RP isolated from either human or bovine milk had similar electrophoretic mobilities on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The partially purified bovine PTH-RP stimulated cAMP production in UMR106-01 and OK cell lines and elicited a concentration-dependent inhibition of sodium-dependent phosphate transport in OK cells. Incubation of milk extracts with an anti-PTH antiserum did not affect their bioactivity, whereas an antihuman PTH-RP 1-34 antiserum markedly reduced the cAMP response of UMR106-01 cells to the immunoabsorbed milk extracts. A PTH antagonist, norleu PTH 3-34, blocked the stimulation of cAMP production in UMR106-01 cells treated with milk extracts. PTH-RP immunoreactivity and bioactivity occurred in milk extracts of diverse animals from both eutherian and metatherian (marsupial) species. Porcine colostrum also had immunoreactive PTH-RP, although the levels were lower than the immunoreactive PTH-RP concentrations observed in milk samples collected at 7 and 14 days of lactation. Thus, a 20-21-KDa PTH-RP is secreted into milk where it could play a role in the development of suckling, newborn animals.